1
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Naffaa MM. Neurogenesis dynamics in the olfactory bulb: deciphering circuitry organization, function, and adaptive plasticity. Neural Regen Res 2025; 20:1565-1581. [PMID: 38934393 PMCID: PMC11688548 DOI: 10.4103/nrr.nrr-d-24-00312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2024] [Revised: 05/20/2024] [Accepted: 05/31/2024] [Indexed: 06/28/2024] Open
Abstract
Adult neurogenesis persists after birth in the subventricular zone, with new neurons migrating to the granule cell layer and glomerular layers of the olfactory bulb, where they integrate into existing circuitry as inhibitory interneurons. The generation of these new neurons in the olfactory bulb supports both structural and functional plasticity, aiding in circuit remodeling triggered by memory and learning processes. However, the presence of these neurons, coupled with the cellular diversity within the olfactory bulb, presents an ongoing challenge in understanding its network organization and function. Moreover, the continuous integration of new neurons in the olfactory bulb plays a pivotal role in regulating olfactory information processing. This adaptive process responds to changes in epithelial composition and contributes to the formation of olfactory memories by modulating cellular connectivity within the olfactory bulb and interacting intricately with higher-order brain regions. The role of adult neurogenesis in olfactory bulb functions remains a topic of debate. Nevertheless, the functionality of the olfactory bulb is intricately linked to the organization of granule cells around mitral and tufted cells. This organizational pattern significantly impacts output, network behavior, and synaptic plasticity, which are crucial for olfactory perception and memory. Additionally, this organization is further shaped by axon terminals originating from cortical and subcortical regions. Despite the crucial role of olfactory bulb in brain functions and behaviors related to olfaction, these complex and highly interconnected processes have not been comprehensively studied as a whole. Therefore, this manuscript aims to discuss our current understanding and explore how neural plasticity and olfactory neurogenesis contribute to enhancing the adaptability of the olfactory system. These mechanisms are thought to support olfactory learning and memory, potentially through increased complexity and restructuring of neural network structures, as well as the addition of new granule granule cells that aid in olfactory adaptation. Additionally, the manuscript underscores the importance of employing precise methodologies to elucidate the specific roles of adult neurogenesis amidst conflicting data and varying experimental paradigms. Understanding these processes is essential for gaining insights into the complexities of olfactory function and behavior.
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Affiliation(s)
- Moawiah M. Naffaa
- Department of Psychology and Neuroscience, Duke University, Durham, NC, USA
- Department of Cell Biology, Duke University School of Medicine, Durham, NC, USA
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2
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Daems C, Baz ES, D'Hooge R, Callaerts-Végh Z, Callaerts P. Gene expression differences in the olfactory bulb associated with differential social interactions and olfactory deficits in Pax6 heterozygous mice. Biol Open 2025; 14:BIO061647. [PMID: 39902612 PMCID: PMC11832127 DOI: 10.1242/bio.061647] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2024] [Accepted: 12/28/2024] [Indexed: 02/05/2025] Open
Abstract
Mutations in the highly conserved Pax6 transcription factor have been implicated in neurodevelopmental disorders and behavioral abnormalities, yet the mechanistic basis of the latter remain poorly understood. Our study, using behavioral phenotyping, has identified aberrant social interactions, characterized by withdrawal behavior, and olfactory deficits in Pax6 heterozygous mutant mice. The molecular mechanisms underlying the observed phenotypes were characterized by means of RNA-sequencing on isolated olfactory bulbs followed by validation with qRT-PCR. Comparative analysis of olfactory bulb transcriptomes further reveals an imbalance between neuronal excitation and inhibition, synaptic dysfunction, and alterations in epigenetic regulation as possible mechanisms underlying the abnormal social behavior. We observe a considerable overlap with autism-associated genes and suggest that studying Pax6-dependent gene regulatory networks may further our insight into molecular mechanisms implicated in autistic-like behaviors in Pax6 mutations, thereby paving the way for future research in this area.
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Affiliation(s)
- Carmen Daems
- Laboratory of Behavioral and Developmental Genetics, Department of Human Genetics, KU Leuven, 3000 Leuven, Belgium
| | - El-Sayed Baz
- Laboratory of Behavioral and Developmental Genetics, Department of Human Genetics, KU Leuven, 3000 Leuven, Belgium
- Zoology Department, Faculty of Science, Suez Canal University, 41522 Ismailia, Egypt
| | - Rudi D'Hooge
- Laboratory of Biological Psychology, KU Leuven, Leuven, Belgium
| | - Zsuzsanna Callaerts-Végh
- Laboratory of Biological Psychology, KU Leuven, Leuven, Belgium
- Mouse behavior core facility mINT, KU Leuven, Leuven, Belgium
| | - Patrick Callaerts
- Laboratory of Behavioral and Developmental Genetics, Department of Human Genetics, KU Leuven, 3000 Leuven, Belgium
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3
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Elhabbari K, Sireci S, Rothermel M, Brunert D. Olfactory deficits in aging and Alzheimer's-spotlight on inhibitory interneurons. Front Neurosci 2024; 18:1503069. [PMID: 39737436 PMCID: PMC11683112 DOI: 10.3389/fnins.2024.1503069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2024] [Accepted: 11/28/2024] [Indexed: 01/01/2025] Open
Abstract
Cognitive function in healthy aging and neurodegenerative diseases like Alzheimer's disease (AD) correlates to olfactory performance. Aging and disease progression both show marked olfactory deficits in humans and rodents. As a clear understanding of what causes olfactory deficits is still missing, research on this topic is paramount to diagnostics and early intervention therapy. A recent development of this research is focusing on GABAergic interneurons. Both aging and AD show a change in excitation/inhibition balance, indicating reduced inhibitory network functions. In the olfactory system, inhibition has an especially prominent role in processing information, as the olfactory bulb (OB), the first relay station of olfactory information in the brain, contains an unusually high number of inhibitory interneurons. This review summarizes the current knowledge on inhibitory interneurons at the level of the OB and the primary olfactory cortices to gain an overview of how these neurons might influence olfactory behavior. We also compare changes in interneuron composition in different olfactory brain areas between healthy aging and AD as the most common neurodegenerative disease. We find that pathophysiological changes in olfactory areas mirror findings from hippocampal and cortical regions that describe a marked cell loss for GABAergic interneurons in AD but not aging. Rather than differences in brain areas, differences in vulnerability were shown for different interneuron populations through all olfactory regions, with somatostatin-positive cells most strongly affected.
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Affiliation(s)
| | | | | | - Daniela Brunert
- Institute of Physiology, RG Neurophysiology and Optogenetics, Medical Faculty, Otto-von-Guericke-University, Magdeburg, Germany
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4
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Wang P, Li S, Li A. Odor representation and coding by the mitral/tufted cells in the olfactory bulb. J Zhejiang Univ Sci B 2024; 25:824-840. [PMID: 39420520 PMCID: PMC11494158 DOI: 10.1631/jzus.b2400051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 07/14/2024] [Indexed: 10/19/2024]
Abstract
The olfactory bulb (OB) is the first relay station in the olfactory system and functions as a crucial hub. It can represent odor information precisely and accurately in an ever-changing environment. As the only output neurons in the OB, mitral/tufted cells encode information such as odor identity and concentration. Recently, the neural strategies and mechanisms underlying odor representation and encoding in the OB have been investigated extensively. Here we review the main progress on this topic. We first review the neurons and circuits involved in odor representation, including the different cell types in the OB and the neural circuits within and beyond the OB. We will then discuss how two different coding strategies-spatial coding and temporal coding-work in the rodent OB. Finally, we discuss potential future directions for this research topic. Overall, this review provides a comprehensive description of our current understanding of how odor information is represented and encoded by mitral/tufted cells in the OB.
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Affiliation(s)
- Panke Wang
- School of Biomedical Engineering, Guangdong Medical University, Dongguan 523808, China
| | - Shan Li
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou 221002, China
| | - An'an Li
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou 221002, China.
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5
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Giaffar H, Shuvaev S, Rinberg D, Koulakov AA. The primacy model and the structure of olfactory space. PLoS Comput Biol 2024; 20:e1012379. [PMID: 39255274 PMCID: PMC11423968 DOI: 10.1371/journal.pcbi.1012379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 09/25/2024] [Accepted: 07/30/2024] [Indexed: 09/12/2024] Open
Abstract
Understanding sensory processing involves relating the stimulus space, its neural representation, and perceptual quality. In olfaction, the difficulty in establishing these links lies partly in the complexity of the underlying odor input space and perceptual responses. Based on the recently proposed primacy model for concentration invariant odor identity representation and a few assumptions, we have developed a theoretical framework for mapping the odor input space to the response properties of olfactory receptors. We analyze a geometrical structure containing odor representations in a multidimensional space of receptor affinities and describe its low-dimensional implementation, the primacy hull. We propose the implications of the primacy hull for the structure of feedforward connectivity in early olfactory networks. We test the predictions of our theory by comparing the existing receptor-ligand affinity and connectivity data obtained in the fruit fly olfactory system. We find that the Kenyon cells of the insect mushroom body integrate inputs from the high-affinity (primacy) sets of olfactory receptors in agreement with the primacy theory.
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Affiliation(s)
- Hamza Giaffar
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Sergey Shuvaev
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
| | - Dmitry Rinberg
- Neuroscience Institute, New York University Langone Health, New York, New York, United States of America
- Center for Neural Science, New York University, New York, New York, United States of America
| | - Alexei A. Koulakov
- Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, United States of America
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6
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Kunkhyen T, Brechbill TR, Berg SPR, Pothuri P, Rangel AN, Gupta A, Cheetham CEJ. Cell type- and layer-specific plasticity of olfactory bulb interneurons following olfactory sensory neuron ablation. Sci Rep 2024; 14:17771. [PMID: 39090136 PMCID: PMC11294461 DOI: 10.1038/s41598-024-68649-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2024] [Accepted: 07/26/2024] [Indexed: 08/04/2024] Open
Abstract
Lifelong neurogenesis endows the mouse olfactory system with a capacity for regeneration that is unique in the mammalian nervous system. Throughout life, olfactory sensory neurons (OSNs) are generated from olfactory epithelium (OE) stem cells in the nose, while the subventricular zone generates neuroblasts that migrate to the olfactory bulb (OB) and differentiate into multiple populations of inhibitory interneurons. Methimazole (MMZ) selectively ablates OSNs, but OE neurogenesis enables OSN repopulation and gradual recovery of OSN input to the OB within 6 weeks. However, it is not known how OB interneurons are affected by this loss and subsequent regeneration of OSN input following MMZ treatment. We found that dopaminergic neuron density was significantly reduced 7-14 days post-MMZ but recovered substantially at 35 days. The density of parvalbumin-expressing interneurons was unaffected by MMZ; however, their soma size was significantly reduced at 7-14 days post-MMZ, recovering by 35 days. Surprisingly, we found a transient increase in the density of calretinin-expressing neurons in the glomerular and external plexiform layers, but not the granule cell layer, 7 days post-MMZ. This could not be accounted for by increased neurogenesis but may result from increased calretinin expression. Together, our data demonstrate cell type- and layer-specific changes in OB interneuron density and morphology after MMZ treatment, providing new insight into the range of plasticity mechanisms employed by OB circuits during loss and regeneration of sensory input.
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Affiliation(s)
- Tenzin Kunkhyen
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Taryn R Brechbill
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Sarah P R Berg
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Pranitha Pothuri
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Alexander N Rangel
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Ashna Gupta
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Claire E J Cheetham
- Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, 15213, USA.
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7
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Burton SD, Malyshko CM, Urban NN. Fast-spiking interneuron detonation drives high-fidelity inhibition in the olfactory bulb. PLoS Biol 2024; 22:e3002660. [PMID: 39186804 PMCID: PMC11379389 DOI: 10.1371/journal.pbio.3002660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 09/06/2024] [Accepted: 07/26/2024] [Indexed: 08/28/2024] Open
Abstract
Inhibitory circuits in the mammalian olfactory bulb (OB) dynamically reformat olfactory information as it propagates from peripheral receptors to downstream cortex. To gain mechanistic insight into how specific OB interneuron types support this sensory processing, we examine unitary synaptic interactions between excitatory mitral and tufted cells (MTCs), the OB projection neurons, and a conserved population of anaxonic external plexiform layer interneurons (EPL-INs) using pair and quartet whole-cell recordings in acute mouse brain slices. Physiological, morphological, neurochemical, and synaptic analyses divide EPL-INs into distinct subtypes and reveal that parvalbumin-expressing fast-spiking EPL-INs (FSIs) perisomatically innervate MTCs with release-competent dendrites and synaptically detonate to mediate fast, short-latency recurrent and lateral inhibition. Sparse MTC synchronization supralinearly increases this high-fidelity inhibition, while sensory afferent activation combined with single-cell silencing reveals that individual FSIs account for a substantial fraction of total network-driven MTC lateral inhibition. OB output is thus powerfully shaped by detonation-driven high-fidelity perisomatic inhibition.
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Affiliation(s)
- Shawn D. Burton
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania, United States of America
| | - Christina M. Malyshko
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania, United States of America
| | - Nathaniel N. Urban
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania, United States of America
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8
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Chen F, He A, Tang Q, Li S, Liu X, Yin Z, Yao Q, Yu Y, Li A. Cholecystokinin-expressing superficial tufted cells modulate odour representation in the olfactory bulb and olfactory behaviours. J Physiol 2024; 602:3519-3543. [PMID: 38837412 DOI: 10.1113/jp285837] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 05/15/2024] [Indexed: 06/07/2024] Open
Abstract
In mammals, odour information within the olfactory bulb (OB) is processed by complex neural circuits before being ultimately represented in the action potential activity of mitral/tufted cells (M/Ts). Cholecystokinin-expressing (CCK+) superficial tufted cells (sTCs) are a subset of tufted cells that potentially contribute to olfactory processing in the OB by orchestrating M/T activity. However, the exact role of CCK+ sTCs in modulating odour processing and olfactory function in vivo is largely unknown. Here, we demonstrate that manipulating CCK+ sTCs can generate perception and induce place avoidance. Optogenetic activation/inactivation of CCK+ sTCs exerted strong but differing effects on spontaneous and odour-evoked M/T firing. Furthermore, inactivation of CCK+ sTCs disrupted M/T odour encoding and impaired olfactory detection and odour discrimination. These results establish the role of CCK+ sTCs in odour representation and olfactory behaviours. KEY POINTS: Mice could perceive the activity of CCK+ sTCs and show place avoidance to CCK+ sTC inactivation. Optical activation of CCK+ sTCs increased the percentage of cells with odour response but reduced the odour-evoked response in M/Ts in awake mice. Optical inactivation of CCK+ sTCs greatly decreased spontaneous firing and odour-evoked response in M/Ts. Inactivation of CCK+ sTCs impairs the odour decoding performance of M/Ts and disrupts odour detection and discrimination behaviours in mice. These results indicate that CCK+ sTCs participate in modulating the odour representation and maintaining normal olfactory-related behaviours.
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Affiliation(s)
- Fengjiao Chen
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Ao He
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Qingnan Tang
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Shan Li
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Xingyu Liu
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Zhaoyang Yin
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Quanbei Yao
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Yiqun Yu
- Ear, Nose & Throat Institute, Department of Otolaryngology, Eye, Ear, Nose & Throat Hospital, Fudan University, Shanghai, China
- Clinical and Research Center for Olfactory Disorders, Eye, Ear, Nose & Throat Hospital, Fudan University, Shanghai, China
| | - Anan Li
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
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9
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Clayton KK, McGill M, Awwad B, Stecyk KS, Kremer C, Skerleva D, Narayanan DP, Zhu J, Hancock KE, Kujawa SG, Kozin ED, Polley DB. Cortical determinants of loudness perception and auditory hypersensitivity. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.30.596691. [PMID: 38853938 PMCID: PMC11160727 DOI: 10.1101/2024.05.30.596691] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2024]
Abstract
Parvalbumin-expressing inhibitory neurons (PVNs) stabilize cortical network activity, generate gamma rhythms, and regulate experience-dependent plasticity. Here, we observed that activation or inactivation of PVNs functioned like a volume knob in the mouse auditory cortex (ACtx), turning neural and behavioral classification of sound level up or down over a 20dB range. PVN loudness adjustments were "sticky", such that a single bout of 40Hz PVN stimulation sustainably suppressed ACtx sound responsiveness, potentiated feedforward inhibition, and behaviorally desensitized mice to loudness. Sensory sensitivity is a cardinal feature of autism, aging, and peripheral neuropathy, prompting us to ask whether PVN stimulation can persistently desensitize mice with ACtx hyperactivity, PVN hypofunction, and loudness hypersensitivity triggered by cochlear sensorineural damage. We found that a single 16-minute bout of 40Hz PVN stimulation session restored normal loudness perception for one week, showing that perceptual deficits triggered by irreversible peripheral injuries can be reversed through targeted cortical circuit interventions.
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Affiliation(s)
- Kameron K Clayton
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA 02114
| | - Matthew McGill
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA 02114
| | - Bshara Awwad
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA 02114
| | - Kamryn S Stecyk
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA 02114
| | - Caroline Kremer
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA 02114
| | | | - Divya P Narayanan
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA 02114
| | - Jennifer Zhu
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA 02114
| | - Kenneth E Hancock
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA 02114
| | - Sharon G Kujawa
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA 02114
| | - Elliott D Kozin
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA 02114
| | - Daniel B Polley
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston MA 02114
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10
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Burton SD, Malyshko CM, Urban NN. Fast-spiking interneuron detonation drives high-fidelity inhibition in the olfactory bulb. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.05.07.592874. [PMID: 38766161 PMCID: PMC11100763 DOI: 10.1101/2024.05.07.592874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2024]
Abstract
Inhibitory circuits in the mammalian olfactory bulb (OB) dynamically reformat olfactory information as it propagates from peripheral receptors to downstream cortex. To gain mechanistic insight into how specific OB interneuron types support this sensory processing, we examine unitary synaptic interactions between excitatory mitral and tufted cells (MTCs), the OB projection cells, and a conserved population of anaxonic external plexiform layer interneurons (EPL-INs) using pair and quartet whole-cell recordings in acute mouse brain slices. Physiological, morphological, neurochemical, and synaptic analyses divide EPL-INs into distinct subtypes and reveal that parvalbumin-expressing fast-spiking EPL-INs (FSIs) perisomatically innervate MTCs with release-competent dendrites and synaptically detonate to mediate fast, short-latency recurrent and lateral inhibition. Sparse MTC synchronization supralinearly increases this high-fidelity inhibition, while sensory afferent activation combined with single-cell silencing reveals that individual FSIs account for a substantial fraction of total network-driven MTC lateral inhibition. OB output is thus powerfully shaped by detonation-driven high-fidelity perisomatic inhibition.
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Affiliation(s)
- Shawn D. Burton
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, USA
| | | | - Nathaniel N. Urban
- Department of Biological Sciences, Lehigh University, Bethlehem, PA, USA
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11
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Lindeman S, Fu X, Reinert JK, Fukunaga I. Value-related learning in the olfactory bulb occurs through pathway-dependent perisomatic inhibition of mitral cells. PLoS Biol 2024; 22:e3002536. [PMID: 38427708 PMCID: PMC10936853 DOI: 10.1371/journal.pbio.3002536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2023] [Revised: 03/13/2024] [Accepted: 02/05/2024] [Indexed: 03/03/2024] Open
Abstract
Associating values to environmental cues is a critical aspect of learning from experiences, allowing animals to predict and maximise future rewards. Value-related signals in the brain were once considered a property of higher sensory regions, but their wide distribution across many brain regions is increasingly recognised. Here, we investigate how reward-related signals begin to be incorporated, mechanistically, at the earliest stage of olfactory processing, namely, in the olfactory bulb. In head-fixed mice performing Go/No-Go discrimination of closely related olfactory mixtures, rewarded odours evoke widespread inhibition in one class of output neurons, that is, in mitral cells but not tufted cells. The temporal characteristics of this reward-related inhibition suggest it is odour-driven, but it is also context-dependent since it is absent during pseudo-conditioning and pharmacological silencing of the piriform cortex. Further, the reward-related modulation is present in the somata but not in the apical dendritic tuft of mitral cells, suggesting an involvement of circuit components located deep in the olfactory bulb. Depth-resolved imaging from granule cell dendritic gemmules suggests that granule cells that target mitral cells receive a reward-related extrinsic drive. Thus, our study supports the notion that value-related modulation of olfactory signals is a characteristic of olfactory processing in the primary olfactory area and narrows down the possible underlying mechanisms to deeper circuit components that contact mitral cells perisomatically.
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Affiliation(s)
- Sander Lindeman
- Sensory and Behavioural Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Xiaochen Fu
- Sensory and Behavioural Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Janine Kristin Reinert
- Sensory and Behavioural Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Izumi Fukunaga
- Sensory and Behavioural Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
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12
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Chen YN, Kostka JK, Bitzenhofer SH, Hanganu-Opatz IL. Olfactory bulb activity shapes the development of entorhinal-hippocampal coupling and associated cognitive abilities. Curr Biol 2023; 33:4353-4366.e5. [PMID: 37729915 PMCID: PMC10617757 DOI: 10.1016/j.cub.2023.08.072] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 08/15/2023] [Accepted: 08/23/2023] [Indexed: 09/22/2023]
Abstract
The interplay between olfaction and higher cognitive processing has been documented in the adult brain; however, its development is poorly understood. In mice, shortly after birth, endogenous and stimulus-evoked activity in the olfactory bulb (OB) boosts the oscillatory entrainment of downstream lateral entorhinal cortex (LEC) and hippocampus (HP). However, it is unclear whether early OB activity has a long-lasting impact on entorhinal-hippocampal function and cognitive processing. Here, we chemogenetically silenced the synaptic outputs of mitral/tufted cells, the main projection neurons in the OB, during postnatal days 8-10. The transient manipulation leads to a long-lasting reduction of oscillatory coupling and weaker responsiveness to stimuli within developing entorhinal-hippocampal circuits accompanied by dendritic sparsification of LEC pyramidal neurons. Moreover, the transient silencing reduces the performance in behavioral tests involving entorhinal-hippocampal circuits later in life. Thus, neonatal OB activity is critical for the functional LEC-HP development and maturation of cognitive abilities.
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Affiliation(s)
- Yu-Nan Chen
- Institute of Developmental Neurophysiology, Center of Molecular Neurobiology, Hamburg Center of Neuroscience, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Johanna K Kostka
- Institute of Developmental Neurophysiology, Center of Molecular Neurobiology, Hamburg Center of Neuroscience, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Sebastian H Bitzenhofer
- Institute of Developmental Neurophysiology, Center of Molecular Neurobiology, Hamburg Center of Neuroscience, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Ileana L Hanganu-Opatz
- Institute of Developmental Neurophysiology, Center of Molecular Neurobiology, Hamburg Center of Neuroscience, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany.
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13
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Fu H, Zhou J, Li S, Zhang Y, Chen Z, Yang Y, Li A, Wang D. Isoflurane impairs olfaction by increasing neuronal activity in the olfactory bulb. Acta Physiol (Oxf) 2023; 239:e14009. [PMID: 37330999 DOI: 10.1111/apha.14009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 05/16/2023] [Accepted: 06/05/2023] [Indexed: 06/20/2023]
Abstract
AIM General anesthesia can induce cognitive deficits in both humans and rodents, correlating with pathological alterations in the hippocampus. However, whether general anesthesia affects olfactory behaviors remains controversial as clinical studies have produced inconsistent results. Therefore, we aimed to investigate how olfactory behaviors and neuronal activity are affected by isoflurane exposure in adult mice. METHODS The olfactory detection test, olfactory sensitivity test, and olfactory preference/avoidance test were used to examine olfactory function. In vivo electrophysiology was performed in awake, head-fixed mice to record single-unit spiking and local field potentials in the olfactory bulb (OB). We also performed patch-clamp recordings of mitral cell activity. For morphological studies, immunofluorescence and Golgi-Cox staining were applied. RESULTS Repeated exposure to isoflurane impaired olfactory detection in adult mice. The main olfactory epithelium, the first region exposed to anesthetics, displayed increased proliferation of basal stem cells. In the OB, a crucial hub for olfactory processing, repeated isoflurane exposure increased the odor responses of mitral/tufted cells. Furthermore, the odor-evoked high gamma response was decreased after isoflurane exposure. Whole-cell recordings further indicated that repeated isoflurane exposure increased the excitability of mitral cells, which may be due to weakened inhibitory input in isoflurane-exposed mice. In addition, elevated astrocyte activation and glutamate transporter-1 expression in the OB were observed in isoflurane-exposed mice. CONCLUSIONS Our findings indicate that repeated isoflurane exposure impairs olfactory detection by increasing neuronal activity in the OB in adult mice.
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Affiliation(s)
- Hanyu Fu
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Jingwei Zhou
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
- Schools of Life Science, Xuzhou Medical University, Xuzhou, China
| | - Shan Li
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Ying Zhang
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Zhiyun Chen
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Yingying Yang
- Schools of Life Science, Xuzhou Medical University, Xuzhou, China
| | - Anan Li
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Dejuan Wang
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
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14
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Pressler RT, Strowbridge BW. Extraglomerular Excitation of Rat Olfactory Bulb Mitral Cells by Depolarizing GABAergic Synaptic Input. J Neurosci 2022; 42:6878-6893. [PMID: 35906068 PMCID: PMC9464016 DOI: 10.1523/jneurosci.0094-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 07/19/2022] [Accepted: 07/22/2022] [Indexed: 11/21/2022] Open
Abstract
Principal cells in the olfactory bulb (OB), mitral and tufted cells, receive direct sensory input and generate output signals that are transmitted to downstream cortical targets. Excitatory input from glutamatergic receptor neurons are the primary known sources of rapid excitation to OB principal cells. Principal cells also receive inhibitory input from local GABAergic interneurons in both the glomerular and plexiform layers. Previous work suggests that the functional effect of these inhibitory inputs, including numerous dendrodendritic synapses with GABAergic granule cells, is to reduce firing probability. In this study, we use in vitro patch-clamp recordings to demonstrate that rat (of both sexes) OB mitral cells also can be excited by GABAergic synapses formed outside the glomerular layer. Depolarizing GABAergic responses to focal extracellular stimulation were revealed when fast ionotropic glutamate receptors were blocked, and occurred with short, monosynaptic latencies. These novel synaptic responses were abolished by gabazine, bicuculline, and picrotoxin, three structurally dissimilar GABAA receptor antagonists. The likely location of depolarizing GABAergic input to mitral cells was the proximal axon based on the actions of focally applied gabazine and GABA near this region. Excitatory GABAergic synaptic responses, commonly studied in cortical brain regions, have not been reported previously in OB principal cells. Excitatory GABAergic responses promote action potential firing and provide a mechanism for mitral cells to be excited independently of olfactory sensory input.SIGNIFICANCE STATEMENT Odor stimuli generate distinctive activity patterns in olfactory bulb neurons through a combination of excitatory and inhibitory synaptic interactions. Most of the excitatory drive to each principal cell is assumed to arise from a highly restricted subset of sensory neurons. This study describes a novel second source of synaptic excitation to principal cells to arise from GABAergic inputs to the proximal axon, a common site of action potential initiation. This new pathway provides a synaptic mechanism to excite OB principal cells that is independent of the canonical excitatory sensory input contained in the glomerular layer.
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Affiliation(s)
- R Todd Pressler
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44106
| | - Ben W Strowbridge
- Department of Neurosciences, Case Western Reserve University, Cleveland, Ohio 44106
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15
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Tan Z, Liu Z, Liu Y, Liu F, Robinson H, Lin TW, Xiong WC, Mei L. An ErbB4-Positive Neuronal Network in the Olfactory Bulb for Olfaction. J Neurosci 2022; 42:6518-6535. [PMID: 35853717 PMCID: PMC9410760 DOI: 10.1523/jneurosci.0131-22.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 06/17/2022] [Accepted: 06/27/2022] [Indexed: 11/21/2022] Open
Abstract
Olfactory information is relayed and processed in the olfactory bulb (OB). Mitral cells, the principal output excitatory neurons of the OB, are controlled by multiple types of interneurons. However, mechanisms that regulate the activity of OB interneurons are not well understood. We provide evidence that the transmembrane tyrosine kinase ErbB4 is selectively expressed in subsets of OB inhibitory neurons in both male and female mice. ErbB4-positive (ErbB4+) neurons are mainly located in the glomerular layer (GL) and granule cell layer (GCL) and do not express previously defined markers. Optogenetic activation of GL-ErbB4+ neurons promotes theta oscillation, whereas activation of those in the GCL generates γ oscillations. Stimulation of OB slices with NRG1, a ligand that activates ErbB4, increases GABA transmission onto mitral cells, suggesting a role of OB NRG1-ErbB4 signaling in olfaction. In accord, ErbB4 mutant mice or acute inhibition of ErbB4 by a chemical genetic approach diminishes GABA transmission, reduces bulbar local field potential power, increases the threshold of olfactory sensitivity, and impairs odor discrimination. Together, these results identified a bulbar inhibitory network of ErbB4+ neurons for olfaction. Considering that both Nrg1 and Erbb4 are susceptibility genes for neuropsychiatric disorders, our study provides insight into pathologic mechanisms of olfactory malfunctions in these disorders.SIGNIFICANCE STATEMENT This study demonstrates that ErbB4+ neurons are a new subset of olfactory bulb inhibitory neurons in the glomerular layer and granule cell layer that innervate mitral cells and ErbB4- cells. They regulate olfaction by controlling local synchrony and distinct oscillations. ErbB4 inhibition diminishes GABA transmission, reduces bulbar local field potential power, increases the threshold of olfactory sensitivity, and impairs odor discrimination. Our results provide insight into pathophysiological mechanism of olfaction deficits in brain disorders associated with Nrg1 or Erbb4 mutations.
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Affiliation(s)
- Zhibing Tan
- Department of Neurosciences, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106
| | - Zhipeng Liu
- Department of Neurosciences, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106
| | - Yu Liu
- Department of Neurosciences, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106
| | - Fang Liu
- Department of Neuroscience and Regeneration Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia 30912
| | - Heath Robinson
- Department of Neurosciences, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106
| | - Thiri W Lin
- Department of Neuroscience and Regeneration Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia 30912
| | - Wen-Cheng Xiong
- Department of Neurosciences, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106
- Louis Strokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio 44016
| | - Lin Mei
- Department of Neurosciences, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106
- Louis Strokes Cleveland Veterans Affairs Medical Center, Cleveland, Ohio 44016
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16
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Aghvami SS, Kubota Y, Egger V. Anatomical and Functional Connectivity at the Dendrodendritic Reciprocal Mitral Cell-Granule Cell Synapse: Impact on Recurrent and Lateral Inhibition. Front Neural Circuits 2022; 16:933201. [PMID: 35937203 PMCID: PMC9355734 DOI: 10.3389/fncir.2022.933201] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 05/27/2022] [Indexed: 11/16/2022] Open
Abstract
In the vertebrate olfactory bulb, reciprocal dendrodendritic interactions between its principal neurons, the mitral and tufted cells, and inhibitory interneurons in the external plexiform layer mediate both recurrent and lateral inhibition, with the most numerous of these interneurons being granule cells. Here, we used recently established anatomical parameters and functional data on unitary synaptic transmission to simulate the strength of recurrent inhibition of mitral cells specifically from the reciprocal spines of rat olfactory bulb granule cells in a quantitative manner. Our functional data allowed us to derive a unitary synaptic conductance on the order of 0.2 nS. The simulations predicted that somatic voltage deflections by even proximal individual granule cell inputs are below the detection threshold and that attenuation with distance is roughly linear, with a passive length constant of 650 μm. However, since recurrent inhibition in the wake of a mitral cell action potential will originate from hundreds of reciprocal spines, the summated recurrent IPSP will be much larger, even though there will be substantial mutual shunting across the many inputs. Next, we updated and refined a preexisting model of connectivity within the entire rat olfactory bulb, first between pairs of mitral and granule cells, to estimate the likelihood and impact of recurrent inhibition depending on the distance between cells. Moreover, to characterize the substrate of lateral inhibition, we estimated the connectivity via granule cells between any two mitral cells or all the mitral cells that belong to a functional glomerular ensemble (i.e., which receive their input from the same glomerulus), again as a function of the distance between mitral cells and/or entire glomerular mitral cell ensembles. Our results predict the extent of the three regimes of anatomical connectivity between glomerular ensembles: high connectivity within a glomerular ensemble and across the first four rings of adjacent glomeruli, substantial connectivity to up to eleven glomeruli away, and negligible connectivity beyond. Finally, in a first attempt to estimate the functional strength of granule-cell mediated lateral inhibition, we combined this anatomical estimate with our above simulation results on attenuation with distance, resulting in slightly narrowed regimes of a functional impact compared to the anatomical connectivity.
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Affiliation(s)
- S. Sara Aghvami
- School of Cognitive Sciences, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran
| | - Yoshiyuki Kubota
- Division of Cerebral Circuitry, National Institute for Physiological Sciences (NIPS), Okazaki, Japan
| | - Veronica Egger
- Neurophysiology, Institute of Zoology, Regensburg University, Regensburg, Germany
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17
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Schubert C, Schulz K, Träger S, Plath AL, Omriouate A, Rosenkranz SC, Morellini F, Friese MA, Hirnet D. Neuronal Adenosine A1 Receptor is Critical for Olfactory Function but Unable to Attenuate Olfactory Dysfunction in Neuroinflammation. Front Cell Neurosci 2022; 16:912030. [PMID: 35846561 PMCID: PMC9279574 DOI: 10.3389/fncel.2022.912030] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Accepted: 06/08/2022] [Indexed: 11/13/2022] Open
Abstract
Adenine nucleotides, such as adenosine triphosphate (ATP), adenosine diphosphate (ADP), as well as the nucleoside adenosine are important modulators of neuronal function by engaging P1 and P2 purinergic receptors. In mitral cells, signaling of the G protein-coupled P1 receptor adenosine 1 receptor (A1R) affects the olfactory sensory pathway by regulating high voltage-activated calcium channels and two-pore domain potassium (K2P) channels. The inflammation of the central nervous system (CNS) impairs the olfactory function and gives rise to large amounts of extracellular ATP and adenosine, which act as pro-inflammatory and anti-inflammatory mediators, respectively. However, it is unclear whether neuronal A1R in the olfactory bulb modulates the sensory function and how this is impacted by inflammation. Here, we show that signaling via neuronal A1R is important for the physiological olfactory function, while it cannot counteract inflammation-induced hyperexcitability and olfactory deficit. Using neuron-specific A1R-deficient mice in patch-clamp recordings, we found that adenosine modulates spontaneous dendro-dendritic signaling in mitral and granule cells via A1R. Furthermore, neuronal A1R deficiency resulted in olfactory dysfunction in two separate olfactory tests. In mice with experimental autoimmune encephalomyelitis (EAE), we detected immune cell infiltration and microglia activation in the olfactory bulb as well as hyperexcitability of mitral cells and olfactory dysfunction. However, neuron-specific A1R activity was unable to attenuate glutamate excitotoxicity in the primary olfactory bulb neurons in vitro or EAE-induced olfactory dysfunction and disease severity in vivo. Together, we demonstrate that A1R modulates the dendro-dendritic inhibition (DDI) at the site of mitral and granule cells and impacts the processing of the olfactory sensory information, while A1R activity was unable to counteract inflammation-induced hyperexcitability.
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Affiliation(s)
- Charlotte Schubert
- Institute of Neuroimmunology and Multiple Sclerosis (INIMS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Kristina Schulz
- Division of Neurophysiology, Institute of Cell and Systems Biology of Animals, University of Hamburg, Hamburg, Germany
| | - Simone Träger
- Institute of Neuroimmunology and Multiple Sclerosis (INIMS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Anna-Lena Plath
- Research Group Behavioral Biology, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Asina Omriouate
- Research Group Behavioral Biology, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sina C. Rosenkranz
- Institute of Neuroimmunology and Multiple Sclerosis (INIMS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Fabio Morellini
- Research Group Behavioral Biology, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Manuel A. Friese
- Institute of Neuroimmunology and Multiple Sclerosis (INIMS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- *Correspondence: Manuel A. Friese,
| | - Daniela Hirnet
- Division of Neurophysiology, Institute of Cell and Systems Biology of Animals, University of Hamburg, Hamburg, Germany
- Daniela Hirnet,
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18
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Dasgupta D, Warner TPA, Erskine A, Schaefer AT. Coupling of Mouse Olfactory Bulb Projection Neurons to Fluctuating Odor Pulses. J Neurosci 2022; 42:4278-4296. [PMID: 35440491 PMCID: PMC9145232 DOI: 10.1523/jneurosci.1422-21.2022] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2021] [Revised: 03/24/2022] [Accepted: 03/29/2022] [Indexed: 11/28/2022] Open
Abstract
Odors are transported by turbulent air currents, creating complex temporal fluctuations in odor concentration that provide a potentially informative stimulus dimension. We have shown that mice are able to discriminate odor stimuli based on their temporal structure, indicating that information contained in the temporal structure of odor plumes can be extracted by the mouse olfactory system. Here, using in vivo extracellular and intracellular electrophysiological recordings, we show that mitral cells (MCs) and tufted cells (TCs) of the male C57BL/6 mouse olfactory bulb can encode the dominant temporal frequencies present in odor stimuli up to at least 20 Hz. A substantial population of cell-odor pairs showed significant coupling of their subthreshold membrane potential with the odor stimulus at both 2 Hz (29/70) and the suprasniff frequency 20 Hz (24/70). Furthermore, mitral/tufted cells (M/TCs) show differential coupling of their membrane potential to odor concentration fluctuations with tufted cells coupling more strongly for the 20 Hz stimulation. Frequency coupling was always observed to be invariant to odor identity, and M/TCs that coupled well to a mixture also coupled to at least one of the components of the mixture. Interestingly, pharmacological blocking of the inhibitory circuitry strongly modulated frequency coupling of cell-odor pairs at both 2 Hz (10/15) and 20 Hz (9/15). These results provide insight into how both cellular and circuit properties contribute to the encoding of temporal odor features in the mouse olfactory bulb.SIGNIFICANCE STATEMENT Odors in the natural environment have a strong temporal structure that can be extracted and used by mice in their behavior. Here, using in vivo extracellular and intracellular electrophysiological techniques, we show that the projection neurons in the olfactory bulb can encode and couple to the dominant frequency present in an odor stimulus. Furthermore, frequency coupling was observed to be differential between mitral and tufted cells and was odor invariant but strongly modulated by local inhibitory circuits. In summary, this study provides insight into how both cellular and circuit properties modulate encoding of odor temporal features in the mouse olfactory bulb.
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Affiliation(s)
- Debanjan Dasgupta
- Sensory Circuits and Neurotechnology Laboratory, Francis Crick Institute, London NW1 1AT, United Kingdom
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
| | - Tom P A Warner
- Sensory Circuits and Neurotechnology Laboratory, Francis Crick Institute, London NW1 1AT, United Kingdom
| | - Andrew Erskine
- Sensory Circuits and Neurotechnology Laboratory, Francis Crick Institute, London NW1 1AT, United Kingdom
| | - Andreas T Schaefer
- Sensory Circuits and Neurotechnology Laboratory, Francis Crick Institute, London NW1 1AT, United Kingdom
- Department of Neuroscience, Physiology and Pharmacology, University College London, London WC1E 6BT, United Kingdom
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19
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Long X, Deng B, Young CK, Liu G, Zhong Z, Chen Q, Yang H, Lv S, Chen ZS, Zhang S. Sharp Tuning of Head Direction and Angular Head Velocity Cells in the Somatosensory Cortex. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2022; 9:e2200020. [PMID: 35297541 PMCID: PMC9109065 DOI: 10.1002/advs.202200020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 02/10/2022] [Indexed: 05/27/2023]
Abstract
Head direction (HD) cells form a fundamental component in the brain's spatial navigation system and are intricately linked to spatial memory and cognition. Although HD cells have been shown to act as an internal neuronal compass in various cortical and subcortical regions, the neural substrate of HD cells is incompletely understood. It is reported that HD cells in the somatosensory cortex comprise regular-spiking (RS, putative excitatory) and fast-spiking (FS, putative inhibitory) neurons. Surprisingly, somatosensory FS HD cells fire in bursts and display much sharper head-directionality than RS HD cells. These FS HD cells are nonconjunctive, rarely theta rhythmic, sparsely connected and enriched in layer 5. Moreover, sharply tuned FS HD cells, in contrast with RS HD cells, maintain stable tuning in darkness; FS HD cells' coexistence with RS HD cells and angular head velocity (AHV) cells in a layer-specific fashion through the somatosensory cortex presents a previously unreported configuration of spatial representation in the neocortex. Together, these findings challenge the notion that FS interneurons are weakly tuned to sensory stimuli, and offer a local circuit organization relevant to the generation and transmission of HD signaling in the brain.
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Affiliation(s)
- Xiaoyang Long
- Department of NeurosurgeryXinqiao HospitalArmy Medical UniversityChongqing400037China
| | - Bin Deng
- Department of NeurosurgeryXinqiao HospitalArmy Medical UniversityChongqing400037China
| | - Calvin K. Young
- Department of PsychologyBrain Health Research CentreUniversity of OtagoDunedin9054New Zealand
| | - Guo‐Long Liu
- Department of NeurosurgeryXinqiao HospitalArmy Medical UniversityChongqing400037China
| | - Zeqi Zhong
- Department of NeurosurgeryXinqiao HospitalArmy Medical UniversityChongqing400037China
| | - Qian Chen
- Center for Biomedical AnalysisCollege of Basic MedicineArmy Medical UniversityChongqing400038China
| | - Hui Yang
- Department of NeurosurgeryXinqiao HospitalArmy Medical UniversityChongqing400037China
| | - Sheng‐Qing Lv
- Department of NeurosurgeryXinqiao HospitalArmy Medical UniversityChongqing400037China
| | - Zhe Sage Chen
- Department of PsychiatryDepartment of Neuroscience and PhysiologyNeuroscience InstituteNew York University School of MedicineNew YorkNY10016USA
| | - Sheng‐Jia Zhang
- Department of NeurosurgeryXinqiao HospitalArmy Medical UniversityChongqing400037China
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20
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Wang D, Wu J, Liu P, Li X, Li J, He M, Li A. VIP interneurons regulate olfactory bulb output and contribute to odor detection and discrimination. Cell Rep 2022; 38:110383. [PMID: 35172159 DOI: 10.1016/j.celrep.2022.110383] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 11/09/2021] [Accepted: 01/24/2022] [Indexed: 11/03/2022] Open
Abstract
In the olfactory bulb (OB), olfactory information represented by mitral/tufted cells (M/Ts) is extensively modulated by local inhibitory interneurons before being transmitted to the olfactory cortex. While the crucial roles of cortical vasoactive-intestinal-peptide-expressing (VIP) interneurons have been extensively studied, their precise function in the OB remains elusive. Here, we identify the synaptic connectivity of VIP interneurons onto mitral cells (MCs) and demonstrate their important role in olfactory behaviors. Optogenetic activation of VIP interneurons reduced both spontaneous and odor-evoked activity of M/Ts in awake mice. Whole-cell recordings revealed that VIP interneurons decrease MC firing through direct inhibitory synaptic connections with MCs. Furthermore, inactivation of VIP interneurons leads to increased MC firing and impaired olfactory detection and odor discrimination. Therefore, our results demonstrate that VIP interneurons control OB output and play critical roles in odor processing and olfactory behaviors.
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Affiliation(s)
- Dejuan Wang
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou 221004, China
| | - Jing Wu
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou 221004, China
| | - Penglai Liu
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou 221004, China
| | - Xiaowen Li
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou 221004, China
| | - Jiaxin Li
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou 221004, China
| | - Miao He
- Department of Neurology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai 200032, China
| | - Anan Li
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou 221004, China.
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21
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Wu J, Liu P, Mao X, Qiu F, Gong L, Wu J, Wang D, He M, Li A. Ablation of microRNAs in VIP + interneurons impairs olfactory discrimination and decreases neural activity in the olfactory bulb. Acta Physiol (Oxf) 2022; 234:e13767. [PMID: 34981885 DOI: 10.1111/apha.13767] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 10/18/2021] [Accepted: 01/01/2022] [Indexed: 12/29/2022]
Abstract
AIM MicroRNAs (miRNAs) are abundantly expressed in vasoactive intestinal peptide expressing (VIP+ ) interneurons and are indispensable for their functional maintenance and survival. Here, we blocked miRNA biogenesis in postmitotic VIP+ interneurons in mice by selectively ablating Dicer, an enzyme essential for miRNA maturation, to study whether ablation of VIP+ miRNA affects olfactory function and neural activity in olfactory centres such as the olfactory bulb, which contains a large number of VIP+ interneurons. METHODS A go/no-go odour discrimination task and a food-seeking test were used to assess olfactory discrimination and olfactory detection. In vivo electrophysiological techniques were used to record single units and local field potentials. RESULTS Olfactory detection and olfactory discrimination behaviours were impaired in VIP+ -specific Dicer-knockout mice. In vivo electrophysiological recordings in awake, head-fixed mice showed that both spontaneous and odour-evoked firing rates were decreased in mitral/tufted cells in knockout mice. The power of ongoing and odour-evoked beta local field potentials response of the olfactory bulb and anterior piriform cortex were dramatically decreased. Furthermore, the coherence of theta oscillations between the olfactory bulb and anterior piriform cortex was decreased. Importantly, Dicer knockout restricted to olfactory bulb VIP+ interneurons recapitulated the behavioural and electrophysiological results of the global knockout. CONCLUSIONS VIP+ miRNAs are an important factor in sensory processing, affecting olfactory function and olfactory neural activity.
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Affiliation(s)
- Jing Wu
- Jiangsu Key Laboratory of Brain Disease and Bioinformation Research Center for Biochemistry and Molecular Biology Xuzhou Medical University Xuzhou China
| | - Penglai Liu
- Jiangsu Key Laboratory of Brain Disease and Bioinformation Research Center for Biochemistry and Molecular Biology Xuzhou Medical University Xuzhou China
| | - Xingfeng Mao
- Jiangsu Key Laboratory of Brain Disease and Bioinformation Research Center for Biochemistry and Molecular Biology Xuzhou Medical University Xuzhou China
| | - Fang Qiu
- Department of Neurology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science Zhongshan Hospital Fudan University Shanghai China
- Department of Anesthesiology Shenzhen Second People's Hospital/The First Affiliated Hospital of Shenzhen University Shenzhen China
| | - Ling Gong
- Department of Neurology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science Zhongshan Hospital Fudan University Shanghai China
| | - Jinyun Wu
- Department of Neurology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science Zhongshan Hospital Fudan University Shanghai China
| | - Dejuan Wang
- Jiangsu Key Laboratory of Brain Disease and Bioinformation Research Center for Biochemistry and Molecular Biology Xuzhou Medical University Xuzhou China
| | - Miao He
- Department of Neurology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science Zhongshan Hospital Fudan University Shanghai China
| | - Anan Li
- Jiangsu Key Laboratory of Brain Disease and Bioinformation Research Center for Biochemistry and Molecular Biology Xuzhou Medical University Xuzhou China
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22
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Chen F, Liu W, Liu P, Wang Z, Zhou Y, Liu X, Li A. α-Synuclein aggregation in the olfactory bulb induces olfactory deficits by perturbing granule cells and granular-mitral synaptic transmission. NPJ Parkinsons Dis 2021; 7:114. [PMID: 34903719 PMCID: PMC8668919 DOI: 10.1038/s41531-021-00259-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 11/21/2021] [Indexed: 11/10/2022] Open
Abstract
Olfactory dysfunction is an early pre-motor symptom of Parkinson's disease (PD) but the neural mechanisms underlying this dysfunction remain largely unknown. Aggregation of α-synuclein is observed in the olfactory bulb (OB) during the early stages of PD, indicating a relationship between α-synuclein pathology and hyposmia. Here we investigate whether and how α-synuclein aggregates modulate neural activity in the OB at the single-cell and synaptic levels. We induced α-synuclein aggregation specifically in the OB via overexpression of double-mutant human α-synuclein by an adeno-associated viral (AAV) vector. We found that α-synuclein aggregation in the OB decreased the ability of mice to detect odors and to perceive attractive odors. The spontaneous activity and odor-evoked firing rates of single mitral/tufted cells (M/Ts) were increased by α-synuclein aggregates with the amplitude of odor-evoked high-gamma oscillations increased. Furthermore, the decreased activity in granule cells (GCs) and impaired inhibitory synaptic function were responsible for the observed hyperactivity of M/Ts induced by α-synuclein aggregates. These results provide direct evidences of the role of α-synuclein aggregates on PD-related olfactory dysfunction and reveal the neural circuit mechanisms by which olfaction is modulated by α-synuclein pathology.
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Affiliation(s)
- Fengjiao Chen
- grid.417303.20000 0000 9927 0537Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Wei Liu
- grid.417303.20000 0000 9927 0537Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Penglai Liu
- grid.417303.20000 0000 9927 0537Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Zhen Wang
- grid.417303.20000 0000 9927 0537School of Life Science, Xuzhou Medical University, Xuzhou, China
| | - You Zhou
- grid.417303.20000 0000 9927 0537School of Life Science, Xuzhou Medical University, Xuzhou, China
| | - Xingyu Liu
- grid.417303.20000 0000 9927 0537School of Life Science, Xuzhou Medical University, Xuzhou, China
| | - Anan Li
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China.
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Environmental enrichment ameliorates high-fat diet induced olfactory deficit and decrease of parvalbumin neurons in the olfactory bulb in mice. Brain Res Bull 2021; 179:13-24. [PMID: 34848271 DOI: 10.1016/j.brainresbull.2021.11.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2021] [Revised: 11/14/2021] [Accepted: 11/24/2021] [Indexed: 11/23/2022]
Abstract
Overweight induced by high-fat diet (HFD) represents one of the major health concerns in modern societies, which can cause lasting peripheral and central metabolic disorders in all age groups. Specifically, childhood obesity could lead to life-long impact on brain development and functioning. On the other hand, environmental enrichment (EE) has been demonstrated to be beneficial for learning and memory. Here, we explored the impact of high-fat diet on olfaction and organization of olfactory bulb cells in adolescent mice, and the effect of EE intervention thereon. Puberty mice (3-week-old) fed with HFD for 10 weeks exhibited poorer odor sensitivity and olfactory memory relative to controls consuming standard chows. The behavioral deficits were rescued in the HFD group with EE intervention. Neuroanatomically, parvalbumin (PV) interneurons in the olfactory bulb (OB) were reduced in the HFD-fed animals relative to control, while EE intervention also normalized this alteration. In contrast, cells expressing calbindin (CB), doublecortin (DCX) in the OB were not altered. Our findings suggest that PV interneurons may play a crucial role in mediating the HFD-induced olfactory deficit in adolescent mice, and can also serve a protective effect of EE against the functional deficit.
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24
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Yan Y, Aierken A, Wang C, Song D, Ni J, Wang Z, Quan Z, Qing H. A potential biomarker of preclinical Alzheimer's disease: The olfactory dysfunction and its pathogenesis-based neural circuitry impairments. Neurosci Biobehav Rev 2021; 132:857-869. [PMID: 34810025 DOI: 10.1016/j.neubiorev.2021.11.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 10/26/2021] [Accepted: 11/07/2021] [Indexed: 01/24/2023]
Abstract
The olfactory dysfunction can signal and act as a potential biomarker of preclinical AD. However, the precise regulatory mechanism of olfactory function on the neural pathogenesis of AD is still unclear. The impairment of neural networks in olfaction system has been shown to be tightly associated with AD. As key brain regions of the olfactory system, the olfactory bulb (OB) and the piriform cortex (PCx) have a profound influence on the olfactory function. Therefore, this review will explore the mechanism of olfactory dysfunction in preclinical AD in the perspective of abnormal neural networks in the OB and PCx and their associated brain regions, especially from two aspects of aberrant oscillations and synaptic plasticity damages, which help better understand the underlying mechanism of olfactory neural network damages related to AD.
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Affiliation(s)
- Yan Yan
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Ailikemu Aierken
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Chunjian Wang
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Da Song
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Junjun Ni
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Zhe Wang
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, The National Clinical Research Center for Geriatric Disease, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Zhenzhen Quan
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.
| | - Hong Qing
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.
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25
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Ran C, Kamalani GNA, Chen X. Modality-Specific Modulation of Temperature Representations in the Spinal Cord after Injury. J Neurosci 2021; 41:8210-8219. [PMID: 34408066 PMCID: PMC8482863 DOI: 10.1523/jneurosci.1104-21.2021] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 08/06/2021] [Accepted: 08/11/2021] [Indexed: 12/25/2022] Open
Abstract
Different types of tissue injury, such as inflammatory and neuropathic conditions, cause modality-specific alternations on temperature perception. There are profound changes in peripheral sensory neurons after injury, but how patterned neuronal activities in the CNS encode injury-induced sensitization to temperature stimuli is largely unknown. Using in vivo calcium imaging and mouse genetics, we show that formalin- and prostaglandin E2-induced inflammation dramatically increase spinal responses to heating and decrease responses to cooling in male and female mice. The reduction of cold response is largely eliminated on ablation of TRPV1-expressing primary sensory neurons, indicating a crossover inhibition of cold response from the hyperactive heat inputs in the spinal cord. Interestingly, chemotherapy medication oxaliplatin can rapidly increase spinal responses to cooling and suppress responses to heating. Together, our results suggest a push-pull mechanism in processing cold and heat inputs and reveal a synergic mechanism to shift thermosensation after injury.SIGNIFICANCE STATEMENT In this paper, we combine our novel in vivo spinal cord two-photon calcium imaging, mouse genetics, and persistent pain models to study how tissue injury alters the sensation of temperature. We discover modality-specific changes of spinal temperature responses in different models of injury. Chemotherapy medication oxaliplatin leads to cold hypersensitivity and heat hyposensitivity. By contrast, inflammation increases heat sensitivity and decreases cold sensitivity. This decrease in cold sensitivity results from the stronger crossover inhibition from the hyperactive heat inputs. Our work reveals the bidirectional change of thermosensitivity by injury and suggests that the crossover inhibitory circuit underlies the shifted thermosensation, providing a mechanism to the biased perception toward a unique thermal modality that was observed clinically in chronic pain patients.
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Affiliation(s)
- Chen Ran
- Department of Biology, Stanford University, Stanford, California 94305
- Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115
| | | | - Xiaoke Chen
- Department of Biology, Stanford University, Stanford, California 94305
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26
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Manzini I, Schild D, Di Natale C. Principles of odor coding in vertebrates and artificial chemosensory systems. Physiol Rev 2021; 102:61-154. [PMID: 34254835 DOI: 10.1152/physrev.00036.2020] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The biological olfactory system is the sensory system responsible for the detection of the chemical composition of the environment. Several attempts to mimic biological olfactory systems have led to various artificial olfactory systems using different technical approaches. Here we provide a parallel description of biological olfactory systems and their technical counterparts. We start with a presentation of the input to the systems, the stimuli, and treat the interface between the external world and the environment where receptor neurons or artificial chemosensors reside. We then delineate the functions of receptor neurons and chemosensors as well as their overall I-O relationships. Up to this point, our account of the systems goes along similar lines. The next processing steps differ considerably: while in biology the processing step following the receptor neurons is the "integration" and "processing" of receptor neuron outputs in the olfactory bulb, this step has various realizations in electronic noses. For a long period of time, the signal processing stages beyond the olfactory bulb, i.e., the higher olfactory centers were little studied. Only recently there has been a marked growth of studies tackling the information processing in these centers. In electronic noses, a third stage of processing has virtually never been considered. In this review, we provide an up-to-date overview of the current knowledge of both fields and, for the first time, attempt to tie them together. We hope it will be a breeding ground for better information, communication, and data exchange between very related but so far little connected fields.
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Affiliation(s)
- Ivan Manzini
- Animal Physiology and Molecular Biomedicine, Justus-Liebig-University Gießen, Gießen, Germany
| | - Detlev Schild
- Institute of Neurophysiology and Cellular Biophysics, University Medical Center, University of Göttingen, Göttingen, Germany
| | - Corrado Di Natale
- Department of Electronic Engineering, University of Rome Tor Vergata, Rome, Italy
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27
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Widespread Inhibition, Antagonism, and Synergy in Mouse Olfactory Sensory Neurons In Vivo. Cell Rep 2021; 31:107814. [PMID: 32610120 DOI: 10.1016/j.celrep.2020.107814] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Revised: 05/05/2020] [Accepted: 06/03/2020] [Indexed: 12/12/2022] Open
Abstract
Sensory information is selectively or non-selectively enhanced and inhibited in the brain, but it remains unclear whether and how this occurs at the most peripheral level. Using in vivo calcium imaging of mouse olfactory bulb and olfactory epithelium in wild-type and mutant animals, we show that odors produce not only excitatory but also inhibitory responses in olfactory sensory neurons (OSNs). Heterologous assays indicate that odorants can act as agonists to some but inverse agonists to other odorant receptors. We also demonstrate that responses to odor mixtures are extensively suppressed or enhanced in OSNs. When high concentrations of odors are mixed, widespread antagonism suppresses the overall response amplitudes and density. In contrast, a mixture of low concentrations of odors often produces synergistic effects and boosts the faint odor inputs. Thus, odor responses are extensively tuned by inhibition, antagonism, and synergy at the most peripheral level, contributing to robust sensory representations.
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28
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Średniawa W, Wróbel J, Kublik E, Wójcik DK, Whittington MA, Hunt MJ. Network and synaptic mechanisms underlying high frequency oscillations in the rat and cat olfactory bulb under ketamine-xylazine anesthesia. Sci Rep 2021; 11:6390. [PMID: 33737621 PMCID: PMC7973548 DOI: 10.1038/s41598-021-85705-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Accepted: 02/25/2021] [Indexed: 11/09/2022] Open
Abstract
Wake-related ketamine-dependent high frequency oscillations (HFO) can be recorded in local field potentials (LFP) from cortical and subcortical regions in rodents. The mechanisms underlying their generation and occurrence in higher mammals are unclear. Unfortunately, anesthetic doses of pure ketamine attenuate HFO, which has precluded their investigation under anesthesia. Here, we show ketamine-xylazine (KX) anesthesia is associated with a prominent 80–130 Hz rhythm in the olfactory bulb (OB) of rats, whereas 30–65 Hz gamma power is diminished. Simultaneous LFP and thermocouple recordings revealed the 80–130 Hz rhythm was dependent on nasal respiration. This rhythm persisted despite surgical excision of the piriform cortex. Silicon probes spanning the dorsoventral aspect of the OB revealed this rhythm was strongest in ventral areas and associated with microcurrent sources about the mitral layer. Pharmacological microinfusion studies revealed dependency on excitatory-inhibitory synaptic activity, but not gap junctions. Finally, a similar rhythm occurred in the OB of KX-anesthetized cats, which shared key features with our rodent studies. We conclude that the activity we report here is driven by nasal airflow, local excitatory-inhibitory interactions, and conserved in higher mammals. Additionally, KX anesthesia is a convenient model to investigate further the mechanisms underlying wake-related ketamine-dependent HFO.
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Affiliation(s)
- Władysław Średniawa
- Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093, Warsaw, Poland.,University of Warsaw, Faculty of Biology, Miecznikowa 1, 02-096, Warsaw, Poland
| | - Jacek Wróbel
- Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093, Warsaw, Poland
| | - Ewa Kublik
- Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093, Warsaw, Poland
| | - Daniel Krzysztof Wójcik
- Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093, Warsaw, Poland.,Faculty of Management and Social Communication, Jagiellonian University, 30-348, Cracow, Poland
| | | | - Mark Jeremy Hunt
- Nencki Institute of Experimental Biology of Polish Academy of Sciences, 3 Pasteur Street, 02-093, Warsaw, Poland. .,University of York, Heslington, NY, YO10 5DD, United Kingdom.
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29
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Chen M, Chen Y, Huo Q, Wang L, Tan S, Misrani A, Jiang J, Chen J, Chen S, Zhang J, Tabassum S, Wang J, Chen X, Long C, Yang L. Enhancing GABAergic signaling ameliorates aberrant gamma oscillations of olfactory bulb in AD mouse models. Mol Neurodegener 2021; 16:14. [PMID: 33663578 PMCID: PMC7934466 DOI: 10.1186/s13024-021-00434-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 02/16/2021] [Indexed: 12/13/2022] Open
Abstract
Background Before the deposition of amyloid-beta plaques and the onset of learning memory deficits, patients with Alzheimer’s disease (AD) experience olfactory dysfunction, typified by a reduced ability to detect, discriminate, and identify odors. Rodent models of AD, such as the Tg2576 and APP/PS1 mice, also display impaired olfaction, accompanied by aberrant in vivo or in vitro gamma rhythms in the olfactory pathway. However, the mechanistic relationships between the electrophysiological, biochemical and behavioral phenomena remain unclear. Methods To address the above issues in AD models, we conducted in vivo measurement of local field potential (LFP) with a combination of in vitro electro-olfactogram (EOG), whole-cell patch and field recordings to evaluate oscillatory and synaptic function and pharmacological regulation in the olfactory pathway, particularly in the olfactory bulb (OB). Levels of protein involved in excitation and inhibition of the OB were investigated by western blotting and fluorescence staining, while behavioral studies assessed olfaction and memory function. Results LFP measurements demonstrated an increase in gamma oscillations in the OB accompanied by altered olfactory behavior in both APP/PS1 and 3xTg mice at 3–5 months old, i.e. an age before the onset of plaque formation. Fewer olfactory sensory neurons (OSNs) and a reduced EOG contributed to a decrease in the excitatory responses of M/T cells, suggesting a decreased ability of M/T cells to trigger interneuron GABA release indicated by altered paired-pulse ratio (PPR), a presynaptic parameter. Postsynaptically, there was a compensatory increase in levels of GABAAR α1 and β3 subunits and subsequent higher amplitude of inhibitory responses. Strikingly, the GABA uptake inhibitor tiagabine (TGB) ameliorated abnormal gamma oscillations and levels of GABAAR subunits, suggesting a potential therapeutic strategy for early AD symptoms. These findings reveal increased gamma oscillations in the OB as a core indicator prior to onset of AD and uncover mechanisms underlying aberrant gamma activity in the OB. Conclusions This study suggests that the concomitant dysfunction of both olfactory behavior and gamma oscillations have important implications for early AD diagnosis: in particular, awareness of aberrant GABAergic signaling mechanisms might both aid diagnosis and suggest therapeutic strategies for olfactory damage in AD. Supplementary Information The online version contains supplementary material available at 10.1186/s13024-021-00434-7.
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Affiliation(s)
- Ming Chen
- Precise Genome Engineering Center, School of Life Sciences, Guangzhou University, Guangzhou, 510006, China.,Department of Pharmacology, Key Laboratory of Anti-inflammatory and Immunopharmacology, School of Basic Medical Sciences, Anhui Medical University, Hefei, 230032, China
| | - Yunan Chen
- School of Life Sciences, South China Normal University, Guangzhou, 510631, China.,Institute for Brain Research and Rehabilitation, South China Normal University, Guangzhou, 510631, China
| | - Qingwei Huo
- Medical College of Acu-Moxi and Rehabilitation, Guangzhou University of Chinese Medicine, Guangzhou, China
| | - Lei Wang
- Precise Genome Engineering Center, School of Life Sciences, Guangzhou University, Guangzhou, 510006, China
| | - Shuyi Tan
- School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Afzal Misrani
- Precise Genome Engineering Center, School of Life Sciences, Guangzhou University, Guangzhou, 510006, China
| | - Jinxiang Jiang
- Precise Genome Engineering Center, School of Life Sciences, Guangzhou University, Guangzhou, 510006, China
| | - Jian Chen
- School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Shiyuan Chen
- School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Jiawei Zhang
- Institute for Brain Research and Rehabilitation, South China Normal University, Guangzhou, 510631, China
| | - Sidra Tabassum
- Precise Genome Engineering Center, School of Life Sciences, Guangzhou University, Guangzhou, 510006, China
| | - Jichen Wang
- School of Psychology and Center for Studies of Psychological Application, South China Normal University, Guangzhou, 510631, China
| | - Xi Chen
- School of Life Sciences, South China Normal University, Guangzhou, 510631, China
| | - Cheng Long
- School of Life Sciences, South China Normal University, Guangzhou, 510631, China.,Institute for Brain Research and Rehabilitation, South China Normal University, Guangzhou, 510631, China
| | - Li Yang
- Precise Genome Engineering Center, School of Life Sciences, Guangzhou University, Guangzhou, 510006, China.
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30
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Egger V, Kuner T. Olfactory bulb granule cells: specialized to link coactive glomerular columns for percept generation and discrimination of odors. Cell Tissue Res 2021; 383:495-506. [PMID: 33404844 PMCID: PMC7873091 DOI: 10.1007/s00441-020-03402-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 12/14/2020] [Indexed: 12/16/2022]
Abstract
The role of granule cells in olfactory processing is surrounded by several enigmatic observations, such as the purpose of reciprocal spines and the mechanisms for GABA release, the apparently low firing activity and recurrent inhibitory drive of granule cells, the missing proof for functional reciprocal connectivity, and the apparently negligible contribution to lateral inhibition. Here, we summarize recent results with regard to both the mechanisms of GABA release and the behavioral relevance of granule cell activity during odor discrimination. We outline a novel hypothesis that has the potential to resolve most of these enigmas and allows further predictions on the function of granule cells in odor processing. Briefly, recent findings imply that GABA release from the reciprocal spine requires a local spine action potential and the cooperative action of NMDA receptors and high voltage-activated Ca2+ channels. Thus, lateral inhibition is conditional on activity in the principal neurons connected to a granule cell and tightly intertwined with recurrent inhibition. This notion allows us to infer that lateral inhibition between principal neurons occurs "on demand," i.e., selectively on coactive mitral and tufted cells, and thus can provide directed, dynamically switched lateral inhibition in a sensory system with 1000 input channels organized in glomerular columns. The mechanistic underpinnings of this hypothesis concur with findings from odor discrimination behavior in mice with synaptic proteins deleted in granule cells. In summary, our hypothesis explains the unusual microcircuit of the granule cell reciprocal spine as a means of olfactory combinatorial coding.
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Affiliation(s)
- Veronica Egger
- Institute of Zoology, Regensburg University, Universitätsstr. 30, 93040, Regensburg, Germany.
| | - Thomas Kuner
- Department of Functional Neuroanatomy, Institute for Anatomy and Cell Biology, Heidelberg University, Im Neuenheimer Feld 307, 69120, Heidelberg, Germany
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31
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Fomin-Thunemann N, Kovalchuk Y, Fink S, Alsema A, Mojtahedi N, Zirdum E, Garaschuk O. Unique Functional Properties of Mature Adult-Born Neurons in the Mouse Olfactory Bulb. Stem Cell Reports 2020; 15:1333-1346. [PMID: 33217326 PMCID: PMC7724478 DOI: 10.1016/j.stemcr.2020.10.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Revised: 10/20/2020] [Accepted: 10/21/2020] [Indexed: 11/19/2022] Open
Abstract
The rodent olfactory bulb (OB) is continuously supplied with adult-born cells maturing into GABAergic neurons. Using in vivo ratiometric Ca2+ imaging to readout ongoing and sensory-driven activity, we asked whether mature adult-born cells (mABCs) in the glomerular layer of the bulb become functionally identical to resident GABAergic (ResGABA) neurons. In awake head-restrained mice the two cell populations differed significantly in terms of ongoing spontaneous activity, with 24% of mABCs contributing to a strongly active cell cluster, absent among ResGABA cells. Odor-evoked responses of mABCs were sparse, less reliable, and had smaller amplitudes compared with ResGABA cells. The opposite was seen under anesthesia, with response reliability increasing and response size of mABCs becoming larger than that of ResGABA cells. Furthermore, ongoing activity of mABCs showed increased sensitivity to ketamine/xylazine and was selectively blocked by the antagonist of serotonin receptors methysergide. These functional features of mABCs clearly distinguish them from other OB interneurons.
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Affiliation(s)
- Natalie Fomin-Thunemann
- Institute of Physiology, Department of Neurophysiology, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Yury Kovalchuk
- Institute of Physiology, Department of Neurophysiology, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Stefan Fink
- Institute of Physiology, Department of Neurophysiology, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Astrid Alsema
- Institute of Physiology, Department of Neurophysiology, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Nima Mojtahedi
- Institute of Physiology, Department of Neurophysiology, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Elizabeta Zirdum
- Institute of Physiology, Department of Neurophysiology, Eberhard Karls University of Tübingen, Tübingen, Germany
| | - Olga Garaschuk
- Institute of Physiology, Department of Neurophysiology, Eberhard Karls University of Tübingen, Tübingen, Germany.
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32
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Lage-Rupprecht V, Zhou L, Bianchini G, Aghvami SS, Mueller M, Rózsa B, Sassoè-Pognetto M, Egger V. Presynaptic NMDARs cooperate with local spikes toward GABA release from the reciprocal olfactory bulb granule cell spine. eLife 2020; 9:e63737. [PMID: 33252329 PMCID: PMC7704106 DOI: 10.7554/elife.63737] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2020] [Accepted: 11/10/2020] [Indexed: 12/16/2022] Open
Abstract
In the rodent olfactory bulb the smooth dendrites of the principal glutamatergic mitral cells (MCs) form reciprocal dendrodendritic synapses with large spines on GABAergic granule cells (GC), where unitary release of glutamate can trigger postsynaptic local activation of voltage-gated Na+-channels (Navs), that is a spine spike. Can such single MC input evoke reciprocal release? We find that unitary-like activation via two-photon uncaging of glutamate causes GC spines to release GABA both synchronously and asynchronously onto MC dendrites. This release indeed requires activation of Navs and high-voltage-activated Ca2+-channels (HVACCs), but also of NMDA receptors (NMDAR). Simulations show temporally overlapping HVACC- and NMDAR-mediated Ca2+-currents during the spine spike, and ultrastructural data prove NMDAR presence within the GABAergic presynapse. This cooperative action of presynaptic NMDARs allows to implement synapse-specific, activity-dependent lateral inhibition, and thus could provide an efficient solution to combinatorial percept synthesis in a sensory system with many receptor channels.
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Affiliation(s)
- Vanessa Lage-Rupprecht
- Neurophysiology, Institute of Zoology, Universität RegensburgRegensburgGermany
- Department of Bioinformatics, Fraunhofer SCAISankt AugustinGermany
| | - Li Zhou
- Neurophysiology, Institute of Zoology, Universität RegensburgRegensburgGermany
| | - Gaia Bianchini
- Neurophysiology, Institute of Zoology, Universität RegensburgRegensburgGermany
| | - S Sara Aghvami
- Neurophysiology, Institute of Zoology, Universität RegensburgRegensburgGermany
- School of Electrical and Computer Engineering, University of TehranTehranIslamic Republic of Iran
- School of Cognitive Sciences, Institute for Research in Fundamental Sciences (IPM)TehranIslamic Republic of Iran
| | - Max Mueller
- Neurophysiology, Institute of Zoology, Universität RegensburgRegensburgGermany
| | - Balázs Rózsa
- Two-Photon Imaging Center, Institute of Experimental Medicine, Hungarian Academy of SciencesBudapestHungary
| | | | - Veronica Egger
- Neurophysiology, Institute of Zoology, Universität RegensburgRegensburgGermany
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33
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Activation of Granule Cell Interneurons by Two Divergent Local Circuit Pathways in the Rat Olfactory Bulb. J Neurosci 2020; 40:9701-9714. [PMID: 33234611 DOI: 10.1523/jneurosci.0989-20.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 10/17/2020] [Accepted: 10/21/2020] [Indexed: 02/07/2023] Open
Abstract
The olfactory bulb (OB) serves as a relay region for sensory information transduced by receptor neurons in the nose and ultimately routed to a variety of cortical areas. Despite the highly structured organization of the sensory inputs to the OB, even simple monomolecular odors activate large regions of the OB comprising many glomerular modules defined by afferents from different receptor neuron subtypes. OB principal cells receive their primary excitatory input from only one glomerular channel defined by inputs from one class of olfactory receptor neurons. By contrast, interneurons, such as GABAergic granule cells (GCs), integrate across multiple channels through dendodendritic inputs on their distal apical dendrites. Through their inhibitory synaptic actions, GCs appear to modulate principal cell firing to enhance olfactory discrimination, although how GCs contribute to olfactory function is not well understood. In this study, we identify a second synaptic pathway by which principal cells in the rat (both sexes) OB excite GCs by evoking potent nondepressing EPSPs (termed large-amplitude, nondendrodendritic [LANDD] EPSPs). LANDD EPSPs show little depression in response to tetanic stimulation and, therefore, can be distinguished other EPSPs that target GCs. LANDD EPSPs can be evoked by both focal stimulation near GC proximal dendrites and by activating sensory inputs in the glomerular layer in truncated GCs lacking dendrodendritic inputs. Using computational simulations, we show that LANDD EPSPs more reliably encode the duration of principal cell discharges than DD EPSPs, enabling GCs to compare contrasting versions of odor-driven activity patterns.SIGNIFICANCE STATEMENT The olfactory bulb plays a critical role in transforming broad sensory input patterns into odor-selective population responses. How this occurs is not well understood, but the local bulbar interneurons appear to be centrally involved in the process. Granule cells, the most common interneuron in the olfactory bulb, are known to broadly integrate sensory input through specialized synapses on their distal dendrites. Here we describe a second class of local excitatory inputs to granule cells that are more powerful than distal inputs and fail to depress with repeated stimulation. This second, proximal pathway allows bulbar interneurons to assay divergent versions of the same sensory input pattern.
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34
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Egger V, Diamond JS. A17 Amacrine Cells and Olfactory Granule Cells: Parallel Processors of Early Sensory Information. Front Cell Neurosci 2020; 14:600537. [PMID: 33250720 PMCID: PMC7674606 DOI: 10.3389/fncel.2020.600537] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Accepted: 10/05/2020] [Indexed: 12/16/2022] Open
Abstract
Neurons typically receive synaptic input in their dendritic arbor, integrate inputs in their soma, and send output action potentials through their axon, following Cajal's law of dynamic polarization. Two notable exceptions are retinal amacrine cells and olfactory granule cells (GCs), which flout Cajal's edict by providing synaptic output from the same dendrites that collect synaptic input. Amacrine cells, a diverse cell class comprising >60 subtypes, employ various dendritic input/output strategies, but A17 amacrine cells (A17s) in particular share further interesting functional characteristics with GCs: both receive excitatory synaptic input from neurons in the primary glutamatergic pathway and return immediate, reciprocal feedback via GABAergic inhibitory synapses to the same synaptic terminals that provided input. Both neurons thereby process signals locally within their dendrites, shaping many parallels, signaling pathways independently. The similarities between A17s and GCs cast into relief striking differences that may indicate distinct processing roles within their respective circuits: First, they employ partially dissimilar molecular mechanisms to transform excitatory input into inhibitory output; second, GCs fire action potentials, whereas A17s do not. Third, GC signals may be influenced by cortical feedback, whereas the mammalian retina receives no such retrograde input. Finally, A17s constitute just one subtype within a diverse class that is specialized in a particular task, whereas the more homogeneous GCs may play more diverse signaling roles via multiple processing modes. Here, we review these analogies and distinctions between A17 amacrine cells and granule cells, hoping to gain further insight into the operating principles of these two sensory circuits.
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Affiliation(s)
- Veronica Egger
- Department of Neurophysiology, Institute of Zoology, Universität Regensburg, Regensburg, Germany
| | - Jeffrey S. Diamond
- Synaptic Physiology Section, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, United States
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Imamura F, Ito A, LaFever BJ. Subpopulations of Projection Neurons in the Olfactory Bulb. Front Neural Circuits 2020; 14:561822. [PMID: 32982699 PMCID: PMC7485133 DOI: 10.3389/fncir.2020.561822] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 08/12/2020] [Indexed: 12/17/2022] Open
Abstract
Generation of neuronal diversity is a biological strategy widely used in the brain to process complex information. The olfactory bulb is the first relay station of olfactory information in the vertebrate central nervous system. In the olfactory bulb, axons of the olfactory sensory neurons form synapses with dendrites of projection neurons that transmit the olfactory information to the olfactory cortex. Historically, the olfactory bulb projection neurons have been classified into two populations, mitral cells and tufted cells. The somata of these cells are distinctly segregated within the layers of the olfactory bulb; the mitral cells are located in the mitral cell layer while the tufted cells are found in the external plexiform layer. Although mitral and tufted cells share many morphological, biophysical, and molecular characteristics, they differ in soma size, projection patterns of their dendrites and axons, and odor responses. In addition, tufted cells are further subclassified based on the relative depth of their somata location in the external plexiform layer. Evidence suggests that different types of tufted cells have distinct cellular properties and play different roles in olfactory information processing. Therefore, mitral and different types of tufted cells are considered as starting points for parallel pathways of olfactory information processing in the brain. Moreover, recent studies suggest that mitral cells also consist of heterogeneous subpopulations with different cellular properties despite the fact that the mitral cell layer is a single-cell layer. In this review, we first compare the morphology of projection neurons in the olfactory bulb of different vertebrate species. Next, we explore the similarities and differences among subpopulations of projection neurons in the rodent olfactory bulb. We also discuss the timing of neurogenesis as a factor for the generation of projection neuron heterogeneity in the olfactory bulb. Knowledge about the subpopulations of olfactory bulb projection neurons will contribute to a better understanding of the complex olfactory information processing in higher brain regions.
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Affiliation(s)
- Fumiaki Imamura
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA, United States
| | - Ayako Ito
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA, United States
| | - Brandon J LaFever
- Department of Pharmacology, Penn State College of Medicine, Hershey, PA, United States
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Aging Alters Olfactory Bulb Network Oscillations and Connectivity: Relevance for Aging-Related Neurodegeneration Studies. Neural Plast 2020; 2020:1703969. [PMID: 32774353 PMCID: PMC7396091 DOI: 10.1155/2020/1703969] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2019] [Revised: 01/27/2020] [Accepted: 02/12/2020] [Indexed: 11/18/2022] Open
Abstract
The aging process eventually cause a breakdown in critical synaptic plasticity and connectivity leading to deficits in memory function. The olfactory bulb (OB) and the hippocampus, both regions of the brain considered critical for the processing of odors and spatial memory, are commonly affected by aging. Using an aged wild-type C57B/6 mouse model, we sought to define the effects of aging on hippocampal plasticity and the integrity of cortical circuits. Specifically, we measured the long-term potentiation of high-frequency stimulation (HFS-LTP) at the Shaffer-Collateral CA1 pyramidal synapses. Next, local field potential (LFP) spectra, phase-amplitude theta-gamma coupling (PAC), and connectivity through coherence were assessed in the olfactory bulb, frontal and entorhinal cortices, CA1, and amygdala circuits. The OB of aged mice showed a significant increase in the number of histone H2AX-positive neurons, a marker of DNA damage. While the input-output relationship measure of basal synaptic activity was found not to differ between young and aged mice, a pronounced decline in the slope of field excitatory postsynaptic potential (fEPSP) and the population spike amplitude (PSA) were found in aged mice. Furthermore, aging was accompanied by deficits in gamma network oscillations, a shift to slow oscillations, reduced coherence and theta-gamma PAC in the OB circuit. Thus, while the basal synaptic activity was unaltered in older mice, impairment in hippocampal synaptic transmission was observed only in response to HFS. However, age-dependent alterations in neural network appeared spontaneously in the OB circuit, suggesting the neurophysiological basis of synaptic deficits underlying olfactory processing. Taken together, the results highlight the sensitivity and therefore potential use of LFP quantitative network oscillations and connectivity at the OB level as objective electrophysiological markers that will help reveal specific dysfunctional circuits in aging-related neurodegeneration studies.
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Ackels T, Jordan R, Schaefer AT, Fukunaga I. Respiration-Locking of Olfactory Receptor and Projection Neurons in the Mouse Olfactory Bulb and Its Modulation by Brain State. Front Cell Neurosci 2020; 14:220. [PMID: 32765224 PMCID: PMC7378796 DOI: 10.3389/fncel.2020.00220] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Accepted: 06/22/2020] [Indexed: 01/10/2023] Open
Abstract
For sensory systems of the brain, the dynamics of an animal’s own sampling behavior has a direct consequence on ensuing computations. This is particularly the case for mammalian olfaction, where a rhythmic flow of air over the nasal epithelium entrains activity in olfactory system neurons in a phenomenon known as sniff-locking. Parameters of sniffing can, however, change drastically with brain states. Coupled to the fact that different observation methods have different kinetics, consensus on the sniff-locking properties of neurons is lacking. To address this, we investigated the sniff-related activity of olfactory sensory neurons (OSNs), as well as the principal neurons of the olfactory bulb (OB), using 2-photon calcium imaging and intracellular whole-cell patch-clamp recordings in vivo, both in anesthetized and awake mice. Our results indicate that OSNs and OB output neurons lock robustly to the sniff rhythm, but with a slight temporal shift between behavioral states. We also observed a slight delay between methods. Further, the divergent sniff-locking by tufted cells (TCs) and mitral cells (MCs) in the absence of odor can be used to determine the cell type reliably using a simple linear classifier. Using this classification on datasets where morphological identification is unavailable, we find that MCs use a wider range of temporal shifts to encode odors than previously thought, while TCs have a constrained timing of activation due to an early-onset hyperpolarization. We conclude that the sniff rhythm serves as a fundamental rhythm but its impact on odor encoding depends on cell type, and this difference is accentuated in awake mice.
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Affiliation(s)
- Tobias Ackels
- Neurophysiology of Behaviour Laboratory, The Francis Crick Institute, London, United Kingdom.,Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Rebecca Jordan
- Neurophysiology of Behaviour Laboratory, The Francis Crick Institute, London, United Kingdom.,Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Andreas T Schaefer
- Neurophysiology of Behaviour Laboratory, The Francis Crick Institute, London, United Kingdom.,Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Izumi Fukunaga
- Sensory and Behavioural Neuroscience Unit, Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
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Zhang X, Meeks JP. Paradoxically Sparse Chemosensory Tuning in Broadly Integrating External Granule Cells in the Mouse Accessory Olfactory Bulb. J Neurosci 2020; 40:5247-5263. [PMID: 32503886 PMCID: PMC7329303 DOI: 10.1523/jneurosci.2238-19.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 04/20/2020] [Accepted: 04/23/2020] [Indexed: 12/20/2022] Open
Abstract
The accessory olfactory bulb (AOB), the first neural circuit in the mouse accessory olfactory system, is critical for interpreting social chemosignals. Despite its importance, AOB information processing is poorly understood compared with the main olfactory bulb (MOB). Here, we sought to fill gaps in the understanding of AOB interneuron function. We used 2-photon GCaMP6f Ca2+ imaging in an ex vivo preparation to study chemosensory tuning in AOB external granule cells (EGCs), interneurons hypothesized to broadly inhibit activity in excitatory mitral cells (MCs). In ex vivo preparations from mice of both sexes, we measured MC and EGC tuning to natural chemosignal blends and monomolecular ligands, finding that EGC tuning was sparser, not broader, than upstream MCs. Simultaneous electrophysiological recording and Ca2+ imaging showed no differences in GCaMP6f-to-spiking relationships in these cell types during simulated sensory stimulation, suggesting that measured EGC sparseness was not due to cell type-dependent variability in GCaMP6f performance. Ex vivo patch-clamp recordings revealed that EGC subthreshold responsivity was far broader than indicated by GCaMP6f Ca2+ imaging, and that monomolecular ligands rarely elicited EGC spiking. These results indicate that EGCs are selectively engaged by chemosensory blends, suggesting different roles for EGCs than analogous interneurons in the MOB.SIGNIFICANCE STATEMENT The mouse accessory olfactory system (AOS) interprets social chemosignals, but we poorly understand AOS information processing. Here, we investigate the functional properties of external granule cells (EGCs), a major class of interneurons in the accessory olfactory bulb (AOB). We hypothesized that EGCs, which are densely innervated by excitatory mitral cells (MCs), would show broad chemosensory tuning, suggesting a role in divisive normalization. Using ex vivo GCaMP6f imaging, we found that EGCs were instead more sparsely tuned than MCs. This was not due to weaker GCaMP6f signaling in EGCs than in MCs. Instead, we found that many MC-activating chemosignals caused only subthreshold EGC responses. This indicates a different role for AOB EGCs compared with analogous cells in the main olfactory bulb.
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Affiliation(s)
- Xingjian Zhang
- University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Julian P Meeks
- University of Texas Southwestern Medical Center, Dallas, Texas 75390
- University of Rochester School of Medicine and Dentistry, Rochester, NY, 14642
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39
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Chemogenetics a robust approach to pharmacology and gene therapy. Biochem Pharmacol 2020; 175:113889. [DOI: 10.1016/j.bcp.2020.113889] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2020] [Accepted: 02/26/2020] [Indexed: 12/20/2022]
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40
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Yu YH, Park DK, Yoo DY, Kim DS. Altered expression of parvalbumin immunoreactivity in rat main olfactory bulb following pilocarpine-induced status epilepticus. BMB Rep 2020. [PMID: 32317084 PMCID: PMC7196189 DOI: 10.5483/bmbrep.2020.53.4.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Epilepsy is a chronic neurological disease characterized by spontaneous recurrent seizures and caused by various factors and mechanisms. Malfunction of the olfactory bulb is frequently observed in patients with epilepsy. However, the morphological changes in the olfactory bulb during epilepsy-induced neuropathology have not been elucidated. Therefore, in the present study, we investigated the expression of parvalbumin (PV), one of the calcium-binding proteins, and morphological changes in the rat main olfactory bulb (MOB) following pilocarpine-induced status epilepticus (SE). Pilocarpine-induced SE resulted in neuronal degeneration in the external plexiform layer (EPL) and glomerular layer (GL) of the MOB. PV immunoreactivity was observed in the neuronal somas and processes in the EPL and GL of the control group. However, six hours after pilocarpine administration, PV expression was remarkably decreased in the neuronal processes compared to the somas and the average number of PV-positive interneurons was significantly decreased. Three months after pilocarpine treatment, the number of PV-positive interneurons was also significantly decreased compared to the 6 hour group in both layers. In addition, the number of NeuN-positive neurons was also significantly decreased in the EPL and GL following pilocarpine treatment. In double immunofluorescence staining for PV and MAP2, the immunoreactivity for MAP2 around the PV-positive neurons was significantly decreased three months after pilocarpine treatment. Therefore, the present findings suggest that decreases in PV-positive GABAergic interneurons and dendritic density in the MOB induced impaired calcium buffering and reciprocal synaptic transmission. Thus, these alterations may be considered key factors aggravating olfactory function in patients with epilepsy.
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Affiliation(s)
- Yeon Hee Yu
- Department of Anatomy, College of Medicine, Soonchunhyang University, Cheonan 31151, Korea
| | - Dae-Kyoon Park
- Department of Anatomy, College of Medicine, Soonchunhyang University, Cheonan 31151, Korea
| | - Dae Young Yoo
- Department of Anatomy, College of Medicine, Soonchunhyang University, Cheonan 31151, Korea
| | - Duk-Soo Kim
- Department of Anatomy, College of Medicine, Soonchunhyang University, Cheonan 31151, Korea
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41
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Brondi M, Moroni M, Vecchia D, Molano-Mazón M, Panzeri S, Fellin T. High-Accuracy Detection of Neuronal Ensemble Activity in Two-Photon Functional Microscopy Using Smart Line Scanning. Cell Rep 2020; 30:2567-2580.e6. [PMID: 32101736 PMCID: PMC7043026 DOI: 10.1016/j.celrep.2020.01.105] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 01/10/2020] [Accepted: 01/29/2020] [Indexed: 11/07/2022] Open
Abstract
Two-photon functional imaging using genetically encoded calcium indicators (GECIs) is one prominent tool to map neural activity. Under optimized experimental conditions, GECIs detect single action potentials in individual cells with high accuracy. However, using current approaches, these optimized conditions are never met when imaging large ensembles of neurons. Here, we developed a method that substantially increases the signal-to-noise ratio (SNR) of population imaging of GECIs by using galvanometric mirrors and fast smart line scan (SLS) trajectories. We validated our approach in anesthetized and awake mice on deep and dense GCaMP6 staining in the mouse barrel cortex during spontaneous and sensory-evoked activity. Compared to raster population imaging, SLS led to increased SNR, higher probability of detecting calcium events, and more precise identification of functional neuronal ensembles. SLS provides a cheap and easily implementable tool for high-accuracy population imaging of neural GCaMP6 signals by using galvanometric-based two-photon microscopes.
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Affiliation(s)
- Marco Brondi
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy; Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy
| | - Monica Moroni
- Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy; Neural Computation Laboratory, Center for Neuroscience and Cognitive Systems @UniTn, Istituto Italiano di Tecnologia, Rovereto, Italy; Center for Mind and Brain Sciences (CIMeC), University of Trento, Trento, Italy
| | - Dania Vecchia
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy; Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy
| | - Manuel Molano-Mazón
- Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy; Neural Computation Laboratory, Center for Neuroscience and Cognitive Systems @UniTn, Istituto Italiano di Tecnologia, Rovereto, Italy
| | - Stefano Panzeri
- Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy; Neural Computation Laboratory, Center for Neuroscience and Cognitive Systems @UniTn, Istituto Italiano di Tecnologia, Rovereto, Italy
| | - Tommaso Fellin
- Optical Approaches to Brain Function Laboratory, Istituto Italiano di Tecnologia, Genova, Italy; Neural Coding Laboratory, Istituto Italiano di Tecnologia, Genova and Rovereto, Italy.
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42
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Li A, Rao X, Zhou Y, Restrepo D. Complex neural representation of odour information in the olfactory bulb. Acta Physiol (Oxf) 2020; 228:e13333. [PMID: 31188539 PMCID: PMC7900671 DOI: 10.1111/apha.13333] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2019] [Revised: 05/29/2019] [Accepted: 05/30/2019] [Indexed: 12/20/2022]
Abstract
The most important task of the olfactory system is to generate a precise representation of odour information under different brain and behavioural states. As the first processing stage in the olfactory system and a crucial hub, the olfactory bulb plays a key role in the neural representation of odours, encoding odour identity, intensity and timing. Although the neural circuits and coding strategies used by the olfactory bulb for odour representation were initially identified in anaesthetized animals, a large number of recent studies focused on neural representation of odorants in the olfactory bulb in awake behaving animals. In this review, we discuss these recent findings, covering (a) the neural circuits for odour representation both within the olfactory bulb and the functional connections between the olfactory bulb and the higher order processing centres; (b) how related factors such as sniffing affect and shape the representation; (c) how the representation changes under different states; and (d) recent progress on the processing of temporal aspects of odour presentation in awake, behaving rodents. We highlight discussion of the current views and emerging proposals on the neural representation of odorants in the olfactory bulb.
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Affiliation(s)
- Anan Li
- Jiangsu Key laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, 221004, China
| | - Xiaoping Rao
- Center of Brain Science, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Key Laboratory of Magnetic Resonance in Biological systems, Wuhan institute of Physics and Mathematics, Chinese Academy of Science, Wuhan, 430072, China
| | - Yang Zhou
- Jiangsu Key laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, 221004, China
| | - Diego Restrepo
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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43
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Hirata T, Shioi G, Abe T, Kiyonari H, Kato S, Kobayashi K, Mori K, Kawasaki T. A Novel Birthdate-Labeling Method Reveals Segregated Parallel Projections of Mitral and External Tufted Cells in the Main Olfactory System. eNeuro 2019; 6:ENEURO.0234-19.2019. [PMID: 31672846 PMCID: PMC6868177 DOI: 10.1523/eneuro.0234-19.2019] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 10/16/2019] [Accepted: 10/19/2019] [Indexed: 01/09/2023] Open
Abstract
A fundamental strategy in sensory coding is parallel processing, whereby unique, distinct features of sensation are computed and projected to the central target in the form of submodal maps. It remains unclear, however, whether such parallel processing strategy is employed in the main olfactory system, which codes the complex hierarchical odor and behavioral scenes. A potential scheme is that distinct subsets of projection neurons in the olfactory bulb (OB) form parallel projections to the targets. Taking advantage of the observation that the distinct projection neurons develop at different times, we developed a Cre-loxP-based method that allows for birthdate-specific labeling of cell bodies and their axon projections in mice. This birthdate tag analysis revealed that the mitral cells (MCs) born in an early developmental stage and the external tufted cells (TCs) born a few days later form segregated parallel projections. Specifically, the latter subset converges the axons onto only two small specific targets, one of which, located at the anterolateral edge of the olfactory tubercle (OT), excludes widespread MC projections. This target is made up of neurons that express dopamine D1 but not D2 receptor and corresponds to the most anterolateral isolation of the CAP compartments (aiCAP) that were defined previously. This finding of segregated projections suggests that olfactory sensing does indeed involve parallel processing of functionally distinct submodalities. Importantly, the birthdate tag method used here may pave the way for deciphering the functional meaning of these individual projection pathways in the future.
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Affiliation(s)
- Tatsumi Hirata
- Brain Function Laboratory, National Institute of Genetics
- Graduate University for Advanced Studies, SOKENDAI, Mishima 411-8540, Japan
| | - Go Shioi
- Laboratory for Genetic Engineering, RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
| | - Takaya Abe
- Laboratory for Genetic Engineering, RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
- Laboratory for Animal Resource Development, RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
| | - Hiroshi Kiyonari
- Laboratory for Genetic Engineering, RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
- Laboratory for Animal Resource Development, RIKEN Center for Biosystems Dynamics Research, Kobe 650-0047, Japan
| | - Shigeki Kato
- Department of Molecular Genetics, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan
| | - Kazuto Kobayashi
- Department of Molecular Genetics, Institute of Biomedical Sciences, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan
| | - Kensaku Mori
- Department of Physiology, Graduate School of Medicine, the University of Tokyo, Tokyo 113-0033, Japan
| | - Takahiko Kawasaki
- Brain Function Laboratory, National Institute of Genetics
- Graduate University for Advanced Studies, SOKENDAI, Mishima 411-8540, Japan
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Frank T, Mönig NR, Satou C, Higashijima SI, Friedrich RW. Associative conditioning remaps odor representations and modifies inhibition in a higher olfactory brain area. Nat Neurosci 2019; 22:1844-1856. [PMID: 31591559 PMCID: PMC6858881 DOI: 10.1038/s41593-019-0495-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 08/09/2019] [Indexed: 11/30/2022]
Abstract
Intelligent behavior involves associations between high-dimensional sensory representations and behaviorally relevant qualities such as valence. Learning of associations involves plasticity of excitatory connectivity but it remains poorly understood how information flow is reorganized in networks and how inhibition contributes to this process. We trained adult zebrafish in an appetitive odor discrimination task and analyzed odor representations in a specific compartment of telencephalic area Dp, the homolog of olfactory cortex. Associative conditioning enhanced responses with a preference for the positively conditioned odor (CS+). Moreover, conditioning systematically remapped odor representations along an axis in coding space that represented attractiveness (valence). Inter-individual variations in this mapping predicted variations in behavioral odor preference. Photoinhibition of interneurons resulted in specific modifications of odor representations that mirrored effects of conditioning and reduced experience-dependent, inter-individual variations in odor-valence mapping. These results reveal an individualized odor-to-valence map that is shaped by inhibition and reorganized during learning.
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Affiliation(s)
- Thomas Frank
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.
| | - Nila R Mönig
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Chie Satou
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland
| | - Shin-Ichi Higashijima
- National Institutes of Natural Sciences, Exploratory Research Center on Life and Living Systems, National Institute for Basic Biology, Okazaki, Japan
| | - Rainer W Friedrich
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland. .,University of Basel, Basel, Switzerland.
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Interneuron Functional Diversity in the Mouse Accessory Olfactory Bulb. eNeuro 2019; 6:ENEURO.0058-19.2019. [PMID: 31358509 PMCID: PMC6712203 DOI: 10.1523/eneuro.0058-19.2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 07/18/2019] [Accepted: 07/19/2019] [Indexed: 01/30/2023] Open
Abstract
In the mouse accessory olfactory bulb (AOB), inhibitory interneurons play an essential role in gating behaviors elicited by sensory exposure to social odors. Several morphological classes have been described, but the full complement of interneurons remains incomplete. In order to develop a more comprehensive view of interneuron function in the AOB, we performed targeted patch clamp recordings from partially overlapping subsets of genetically labeled and morphologically defined interneuron types. Gad2 (GAD65), Calb2 (calretinin), and Cort (cortistatin)-cre mouse lines were used to drive selective expression of tdTomato in AOB interneurons. Gad2 and Calb2-labeled interneurons were found in the internal, external, and glomerular (GL) layers, whereas Cort-labeled interneurons were enriched within the lateral olfactory tract (LOT) and external cellular layer (ECL). We found that external granule cells (EGCs) from all genetically labeled subpopulations possessed intrinsic functional differences that allowed them to be readily distinguished from internal granule cells (IGCs). EGCs showed stronger voltage-gated Na+ and non-inactivating voltage-gated K+ currents, decreased IH currents, and robust excitatory synaptic input. These specific intrinsic properties did not correspond to any genetically labeled type, suggesting that transcriptional heterogeneity among EGCs and IGCs is not correlated with expression of these particular marker genes. Intrinsic heterogeneity was also seen among AOB juxtaglomerular cells (JGCs), with a major subset of Calb2-labeled JGCs exhibiting spontaneous and depolarization-evoked plateau potentials. These data identify specific physiological features of AOB interneurons types that will assist in future studies of AOB function.
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Notsu E, Toida K. Examination of morphological and synaptic features of calbindin-immunoreactive neurons in deep layers of the rat olfactory bulb with correlative laser and volume electron microscopy. Microscopy (Oxf) 2019; 68:316-329. [PMID: 31062844 DOI: 10.1093/jmicro/dfz019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 03/21/2019] [Accepted: 04/09/2019] [Indexed: 06/09/2023] Open
Abstract
The olfactory bulb (OB) contains various interneuron types that play key roles in processing olfactory information via synaptic contacts. Many previous studies have reported synaptic connections of heterogeneous interneurons in superficial OB layers. In contrast, few studies have examined synaptic connections in deep layers because of the lack of a selective marker for intrinsic neurons located in the deeper layers, including the mitral cell layer, internal plexiform layer (IPL) and granule cell layer. However, neural circuits in the deep layers are likely to have a strong effect on the output of the OB because of the cellular composition of these regions. Here, we analyzed the calbindin-immunoreactive neurons in the IPL, one of the clearly neurochemically defined interneuron types in the deep layers, using multiple immunolabeling and confocal laser scanning microscopy combined with electron microscopic three-dimensional serial-section reconstruction, enabling correlated laser and volume electron microscopy (EM). Despite a resemblance to the morphological features of deep short axon cells, IPL calbindin-immunoreactive (IPL-CB-ir) neurons lacked axons. Furthermore, multiple immunolabeling for plural neurochemicals indicated that IPL-CB-ir neurons differed from any interneuron types reported previously. We identified symmetrical synapses formed by IPL-CB-ir neurons on granule cells (GCs) using correlated laser and volume EM. These synapses might inhibit GCs and thus disinhibit mitral and tufted cells. Our present findings indicate, for the first time, that IPL-CB-ir neurons are involved in regulating the activities of projection neurons, further suggesting their involvement in synaptic circuitry for output from the deeper layers of the OB, which has not previously been clarified.
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Affiliation(s)
- Eiji Notsu
- Department of Anatomy, Kawasaki Medical School, Kurashiki, Okayama 701-0192, Japan
| | - Kazunori Toida
- Department of Anatomy, Kawasaki Medical School, Kurashiki, Okayama 701-0192, Japan
- Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, Ibaraki, Osaka 567-0047, Japan
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47
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Target specific functions of EPL interneurons in olfactory circuits. Nat Commun 2019; 10:3369. [PMID: 31358754 PMCID: PMC6662826 DOI: 10.1038/s41467-019-11354-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 06/27/2019] [Indexed: 12/02/2022] Open
Abstract
Inhibitory interneurons are integral to sensory processing, yet revealing their cell type-specific roles in sensory circuits remains an ongoing focus. To Investigate the mouse olfactory system, we selectively remove GABAergic transmission from a subset of olfactory bulb interneurons, EPL interneurons (EPL-INs), and assay odor responses from their downstream synaptic partners — tufted cells and mitral cells. Using a combination of in vivo electrophysiological and imaging analyses, we find that inactivating this single node of inhibition leads to differential effects in magnitude, reliability, tuning width, and temporal dynamics between the two principal neurons. Furthermore, tufted and not mitral cell responses to odor mixtures become more linearly predictable without EPL-IN inhibition. Our data suggest that olfactory bulb interneurons, through exerting distinct inhibitory functions onto their different synaptic partners, play a significant role in the processing of odor information. The precise cell-type specific role of inhibitory interneurons in regulating sensory responses in the olfactory bulb is not known. Here, the authors report that removing GABAergic inhibition from one layer differentially affects response dynamics of the two main output cell types and changes odor mixture processing.
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Luo L, Callaway EM, Svoboda K. Genetic Dissection of Neural Circuits: A Decade of Progress. Neuron 2019; 98:256-281. [PMID: 29673479 DOI: 10.1016/j.neuron.2018.03.040] [Citation(s) in RCA: 259] [Impact Index Per Article: 43.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 03/16/2018] [Accepted: 03/21/2018] [Indexed: 01/24/2023]
Abstract
Tremendous progress has been made since Neuron published our Primer on genetic dissection of neural circuits 10 years ago. Since then, cell-type-specific anatomical, neurophysiological, and perturbation studies have been carried out in a multitude of invertebrate and vertebrate organisms, linking neurons and circuits to behavioral functions. New methods allow systematic classification of cell types and provide genetic access to diverse neuronal types for studies of connectivity and neural coding during behavior. Here we evaluate key advances over the past decade and discuss future directions.
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Affiliation(s)
- Liqun Luo
- Department of Biology, Howard Hughes Medical Institute, Stanford University, Stanford, CA 94305, USA
| | - Edward M Callaway
- Systems Neurobiology Laboratory, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, CA 92037, USA.
| | - Karel Svoboda
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA 20147, USA
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Zhang X, Yan W, Wang W, Fan H, Hou R, Chen Y, Chen Z, Ge C, Duan S, Compte A, Li CT. Active information maintenance in working memory by a sensory cortex. eLife 2019; 8:43191. [PMID: 31232695 PMCID: PMC6634975 DOI: 10.7554/elife.43191] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Accepted: 06/20/2019] [Indexed: 11/16/2022] Open
Abstract
Working memory is a critical brain function for maintaining and manipulating information over delay periods of seconds. It is debated whether delay-period neural activity in sensory regions is important for the active maintenance of information during the delay period. Here, we tackle this question by examining the anterior piriform cortex (APC), an olfactory sensory cortex, in head-fixed mice performing several olfactory working memory tasks. Active information maintenance is necessary in these tasks, especially in a dual-task paradigm in which mice are required to perform another distracting task while actively maintaining information during the delay period. Optogenetic suppression of neuronal activity in APC during the delay period impaired performance in all the tasks. Furthermore, electrophysiological recordings revealed that APC neuronal populations encoded odor information in the delay period even with an intervening distracting task. Thus, delay activity in APC is important for active information maintenance in olfactory working memory.
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Affiliation(s)
- Xiaoxing Zhang
- State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Neuroscience, Shanghai Center for Brain Science and Brain-Inspired Technology, Chinese Academy of Sciences, Shanghai, China
| | - Wenjun Yan
- State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Neuroscience, Shanghai Center for Brain Science and Brain-Inspired Technology, Chinese Academy of Sciences, Shanghai, China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Wenliang Wang
- State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Neuroscience, Shanghai Center for Brain Science and Brain-Inspired Technology, Chinese Academy of Sciences, Shanghai, China
| | - Hongmei Fan
- State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Neuroscience, Shanghai Center for Brain Science and Brain-Inspired Technology, Chinese Academy of Sciences, Shanghai, China
| | - Ruiqing Hou
- State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Neuroscience, Shanghai Center for Brain Science and Brain-Inspired Technology, Chinese Academy of Sciences, Shanghai, China
| | - Yulei Chen
- State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Neuroscience, Shanghai Center for Brain Science and Brain-Inspired Technology, Chinese Academy of Sciences, Shanghai, China
| | - Zhaoqin Chen
- State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Neuroscience, Shanghai Center for Brain Science and Brain-Inspired Technology, Chinese Academy of Sciences, Shanghai, China
| | - Chaofan Ge
- State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Neuroscience, Shanghai Center for Brain Science and Brain-Inspired Technology, Chinese Academy of Sciences, Shanghai, China.,School of Future Technology, University of Chinese Academy of Sciences, Beijing, China
| | - Shumin Duan
- Key Laboratory of Medical Neurobiology of Ministry of Health of China, Department of Neurobiology, Zhejiang University School of Medicine, Hangzhou, China.,Key Laboratory of Neurobiology of Zhejiang Province, Department of Neurobiology, Zhejiang University School of Medicine, Hangzhou, China
| | - Albert Compte
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Chengyu T Li
- State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Institute of Neuroscience, Shanghai Center for Brain Science and Brain-Inspired Technology, Chinese Academy of Sciences, Shanghai, China
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50
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Lee TK, Park JH, Ahn JH, Park YE, Park CW, Lee JC, Choi JH, Hwang IK, Kim S, Shim J, Go S, Lee E, Seo K, Won MH. Parvalbumin-immunoreactive cells in the olfactory bulb of the pigeon: Comparison with the rat. Anat Histol Embryol 2019; 48:334-339. [PMID: 31016783 DOI: 10.1111/ahe.12445] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Accepted: 03/30/2019] [Indexed: 11/27/2022]
Abstract
The olfactory bulb (OB) shows special characteristics in its phylogenetic cortical structure and synaptic pattern. In the OB, gamma-aminobutyric acid (GABA), as an inhibitory neurotransmitter, is secreted from GABAergic neurons which contain parvalbumin (a calcium-binding protein). Many studies on the distribution of parvalbumin-immunoreactive neurons in the rodent OB have been published but poorly reported in the avian OB. Therefore, in this study, we compared the structure of the OB and distribution of parvalbumin-immunoreactive neurons in the OB between the rat and pigeon using cresyl violet staining and immunohistochemistry for parvalbumin, respectively. Fundamentally, the pigeon OB showed layers like those of the rat OB; however, some layers were not clear like in the rat OB. Parvalbumin-immunoreactive neurons in the pigeon OB were predominantly distributed in the external plexiform layer like that in the rat OB; however, the neurons did not have long processes like those in the rat. Furthermore, parvalbumin-immunoreactive fibres were abundant in some layers; this finding was not shown in the rat OB. In brief, parvalbumin-immunoreactive neurons were found like those in the rat OB; however, parvalbumin-immunoreactive fibres were significantly abundant in the pigeon OB compared to those in the rat OB.
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Affiliation(s)
- Tae-Kyeong Lee
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, Republic of Korea
| | - Joon Ha Park
- Department of Biomedical Science and Research Institute for Bioscience and Biotechnology, Hallym University, Chuncheon, Republic of Korea
| | - Ji Hyeon Ahn
- Department of Biomedical Science and Research Institute for Bioscience and Biotechnology, Hallym University, Chuncheon, Republic of Korea
| | - Young Eun Park
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, Republic of Korea
| | - Cheol Woo Park
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, Republic of Korea
| | - Jae-Chul Lee
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, Republic of Korea
| | - Jung Hoon Choi
- Department of Anatomy, College of Veterinary Medicine, Kangwon National University, Chuncheon, Republic of Korea
| | - In Koo Hwang
- Department of Anatomy and Cell Biology, College of Veterinary Medicine, and Research Institute for Veterinary Science, Seoul National University, Seoul, Republic of Korea
| | - Sunhyo Kim
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, Republic of Korea
| | - Jaeho Shim
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, Republic of Korea
| | - Seokmin Go
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, Republic of Korea
| | - Eunji Lee
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, Republic of Korea
| | - Kangmoon Seo
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine and Research Institute for Veterinary Science, Seoul National University, Seoul, Republic of Korea
| | - Moo-Ho Won
- Department of Neurobiology, School of Medicine, Kangwon National University, Chuncheon, Republic of Korea
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