1
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Venegas JP, Navarrete M, Orellana-Garcia L, Rojas M, Avello-Duarte F, Nunez-Parra A. Basal Forebrain Modulation of Olfactory Coding In Vivo. Int J Psychol Res (Medellin) 2023; 16:62-86. [PMID: 38106956 PMCID: PMC10723750 DOI: 10.21500/20112084.6486] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 08/23/2022] [Accepted: 12/07/2022] [Indexed: 12/19/2023] Open
Abstract
Sensory perception is one of the most fundamental brain functions, allowing individuals to properly interact and adapt to a constantly changing environment. This process requires the integration of bottom-up and topdown neuronal activity, which is centrally mediated by the basal forebrain, a brain region that has been linked to a series of cognitive processes such as attention and alertness. Here, we review the latest research using optogenetic approaches in rodents and in vivo electrophysiological recordings that are shedding light on the role of this region, in regulating olfactory processing and decisionmaking. Moreover, we summarize evidence highlighting the anatomical and physiological differences in the basal forebrain of individuals with autism spectrum disorder, which could underpin the sensory perception abnormalities they exhibit, and propose this research line as a potential opportunity to understand the neurobiological basis of this disorder.
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Affiliation(s)
- Juan Pablo Venegas
- Physiology Laboratory, Biology Department, Faculty of Science, University of Chile, Chile.Universidad de ChileUniversity of ChileChile
| | - Marcela Navarrete
- Physiology Laboratory, Biology Department, Faculty of Science, University of Chile, Chile.Universidad de ChileUniversity of ChileChile
| | - Laura Orellana-Garcia
- Physiology Laboratory, Biology Department, Faculty of Science, University of Chile, Chile.Universidad de ChileUniversity of ChileChile
| | - Marcelo Rojas
- Physiology Laboratory, Biology Department, Faculty of Science, University of Chile, Chile.Universidad de ChileUniversity of ChileChile
| | - Felipe Avello-Duarte
- Physiology Laboratory, Biology Department, Faculty of Science, University of Chile, Chile.Universidad de ChileUniversity of ChileChile
| | - Alexia Nunez-Parra
- Physiology Laboratory, Biology Department, Faculty of Science, University of Chile, Chile.Universidad de ChileUniversity of ChileChile
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2
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Brunert D, Quintela RM, Rothermel M. The anterior olfactory nucleus revisited - an emerging role for neuropathological conditions? Prog Neurobiol 2023:102486. [PMID: 37343762 DOI: 10.1016/j.pneurobio.2023.102486] [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: 12/23/2022] [Revised: 06/14/2023] [Accepted: 06/16/2023] [Indexed: 06/23/2023]
Abstract
Olfaction is an important sensory modality for many species and greatly influences animal and human behavior. Still, much about olfactory perception remains unknown. The anterior olfactory nucleus is one of the brain's central early olfactory processing areas. Located directly posterior to the olfactory bulb in the olfactory peduncle with extensive in- and output connections and unique cellular composition, it connects olfactory processing centers of the left and right hemispheres. Almost 20 years have passed since the last comprehensive review on the anterior olfactory nucleus has been published and significant advances regarding its anatomy, function, and pathophysiology have been made in the meantime. Here we briefly summarize previous knowledge on the anterior olfactory nucleus, give detailed insights into the progress that has been made in recent years, and map out its emerging importance in translational research of neurological diseases.
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Affiliation(s)
- Daniela Brunert
- Institute of Physiology, Medical Faculty, Otto-von-Guericke-University, 39120 Magdeburg, Germany
| | | | - Markus Rothermel
- Institute of Physiology, Medical Faculty, Otto-von-Guericke-University, 39120 Magdeburg, Germany.
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3
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Chae H, Banerjee A, Dussauze M, Albeanu DF. Long-range functional loops in the mouse olfactory system and their roles in computing odor identity. Neuron 2022; 110:3970-3985.e7. [PMID: 36174573 PMCID: PMC9742324 DOI: 10.1016/j.neuron.2022.09.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 07/12/2022] [Accepted: 09/02/2022] [Indexed: 12/15/2022]
Abstract
Elucidating the neural circuits supporting odor identification remains an open challenge. Here, we analyze the contribution of the two output cell types of the mouse olfactory bulb (mitral and tufted cells) to decode odor identity and concentration and its dependence on top-down feedback from their respective major cortical targets: piriform cortex versus anterior olfactory nucleus. We find that tufted cells substantially outperform mitral cells in decoding both odor identity and intensity. Cortical feedback selectively regulates the activity of its dominant bulb projection cell type and implements different computations. Piriform feedback specifically restructures mitral responses, whereas feedback from the anterior olfactory nucleus preferentially controls the gain of tufted representations without altering their odor tuning. Our results identify distinct functional loops involving the mitral and tufted cells and their cortical targets. We suggest that in addition to the canonical mitral-to-piriform pathway, tufted cells and their target regions are ideally positioned to compute odor identity.
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Affiliation(s)
- Honggoo Chae
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - Arkarup Banerjee
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA; Cold Spring Harbor Laboratory School for Biological Sciences, Cold Spring Harbor, NY, USA
| | - Marie Dussauze
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA; Cold Spring Harbor Laboratory School for Biological Sciences, Cold Spring Harbor, NY, USA
| | - Dinu F Albeanu
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA; Cold Spring Harbor Laboratory School for Biological Sciences, Cold Spring Harbor, NY, USA.
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4
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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: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [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
- *Correspondence: Veronica Egger,
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5
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Capsoni S, Fogli Iseppe A, Casciano F, Pignatelli A. Unraveling the Role of Dopaminergic and Calretinin Interneurons in the Olfactory Bulb. Front Neural Circuits 2021; 15:718221. [PMID: 34690707 PMCID: PMC8531203 DOI: 10.3389/fncir.2021.718221] [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: 05/31/2021] [Accepted: 08/31/2021] [Indexed: 11/27/2022] Open
Abstract
The perception and discriminating of odors are sensory activities that are an integral part of our daily life. The first brain region where odors are processed is the olfactory bulb (OB). Among the different cell populations that make up this brain area, interneurons play an essential role in this sensory activity. Moreover, probably because of their activity, they represent an exception compared to other parts of the brain, since OB interneurons are continuously generated in the postnatal and adult period. In this review, we will focus on periglomerular (PG) cells which are a class of interneurons found in the glomerular layer of the OB. These interneurons can be classified into distinct subtypes based on their neurochemical nature, based on the neurotransmitter and calcium-binding proteins expressed by these cells. Dopaminergic (DA) periglomerular cells and calretinin (CR) cells are among the newly generated interneurons and play an important role in the physiology of OB. In the OB, DA cells are involved in the processing of odors and the adaptation of the bulbar network to external conditions. The main role of DA cells in OB appears to be the inhibition of glutamate release from olfactory sensory fibers. Calretinin cells are probably the best morphologically characterized interneurons among PG cells in OB, but little is known about their function except for their inhibitory effect on noisy random excitatory signals arriving at the main neurons. In this review, we will mainly describe the electrophysiological properties related to the excitability profiles of DA and CR cells, with a particular view on the differences that characterize DA mature interneurons from cells in different stages of adult neurogenesis.
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Affiliation(s)
- Simona Capsoni
- Department of Neuroscience and Rehabilitation, University of Ferrara, Ferrara, Italy
- Bio@SNS Laboratory of Biology, Scuola Normale Superiore, Pisa, Italy
| | - Alex Fogli Iseppe
- Department of Neuroscience and Rehabilitation, University of Ferrara, Ferrara, Italy
| | - Fabio Casciano
- Department of Translational Medicine and LTTA Centre, University of Ferrara, Ferrara, Italy
- Interdepartmental Research Centre for the Study of Multiple Sclerosis and Inflammatory and Degenerative Diseases of the Nervous System, University of Ferrara, Ferrara, Italy
| | - Angela Pignatelli
- Department of Neuroscience and Rehabilitation, University of Ferrara, Ferrara, Italy
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Tavoni G, Kersen DEC, Balasubramanian V. Cortical feedback and gating in odor discrimination and generalization. PLoS Comput Biol 2021; 17:e1009479. [PMID: 34634035 PMCID: PMC8530364 DOI: 10.1371/journal.pcbi.1009479] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2021] [Revised: 10/21/2021] [Accepted: 09/24/2021] [Indexed: 11/30/2022] Open
Abstract
A central question in neuroscience is how context changes perception. In the olfactory system, for example, experiments show that task demands can drive divergence and convergence of cortical odor responses, likely underpinning olfactory discrimination and generalization. Here, we propose a simple statistical mechanism for this effect based on unstructured feedback from the central brain to the olfactory bulb, which represents the context associated with an odor, and sufficiently selective cortical gating of sensory inputs. Strikingly, the model predicts that both convergence and divergence of cortical odor patterns should increase when odors are initially more similar, an effect reported in recent experiments. The theory in turn predicts reversals of these trends following experimental manipulations and in neurological conditions that increase cortical excitability.
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Affiliation(s)
- Gaia Tavoni
- Computational Neuroscience Initiative, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Neuroscience, Washington University in St. Louis, St. Louis, Missouri, United States of America
| | - David E. Chen Kersen
- Computational Neuroscience Initiative, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Vijay Balasubramanian
- Computational Neuroscience Initiative, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Neuroscience, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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7
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Kosenko PO, Smolikov AB, Voynov VB, Shaposhnikov PD, Saevskiy AI, Kiroy VN. Effect of Xylazine-Tiletamine-Zolazepam on the Local Field Potential of the Rat Olfactory Bulb. Comp Med 2020; 70:492-498. [PMID: 33168131 DOI: 10.30802/aalas-cm-20-990015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Neural oscillations of the mammalian olfactory system have been studied for decades. This research suggests they are linked to various processes involved in odor information analysis, depending on the vigilance state and presentation of stimuli. In addition, the effects of various anesthetics, including commonly used ones like chloral hydrate, pentobarbital, ketamine, and urethane, on the local field potential (LFP) in the olfactory bulb (OB) have been studied. In particular, the combination of xylazine and tiletamine-zolazepam has been shown to produce steady anesthesia for an extended period and relatively few adverse effects; however, their effects on the LFP in the OB remain unknown. To study those effects, we recorded the LFP in the OB of rats under xylazine-tiletamine-zolazepam anesthesia. During the period of anesthesia, the spectral powers of the 1-4, 9-16, 31-64, 65-90 frequency bands increased significantly, and that of 91-170 Hz frequency band decreased significantly, whereas no significant changes were observed in the 5-8 and 17-30 Hz ranges. These results reveal dynamic changes in the time and frequency characteristics of the LFP in the OB of rats under xylazine-tiletamine- zolazepam anesthesia and suggest that this combination of anesthetics could be used for studying oscillatory processes in the OB of rats.
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8
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Abstract
Axons from the olfactory bulb (OB) project to multiple central structures of the brain, many of which, in turn, send axons back into the OB and/or to one another. These secondary sensory regions underlie many aspects of odor representation, valence, and learning, as well as serving some nonolfactory functions, though many details remain unclear. We here describe the connectivity and essential structural and functional properties of these postbulbar olfactory regions in the mammalian brain.
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Affiliation(s)
- Thomas A Cleland
- Department of Psychology, Cornell University, Ithaca, NY, United States.
| | - Christiane Linster
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, United States
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9
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Amygdala Corticofugal Input Shapes Mitral Cell Responses in the Accessory Olfactory Bulb. eNeuro 2018; 5:eN-NWR-0175-18. [PMID: 29911171 PMCID: PMC6001136 DOI: 10.1523/eneuro.0175-18.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 05/10/2018] [Accepted: 05/10/2018] [Indexed: 01/11/2023] Open
Abstract
Interconnections between the olfactory bulb and the amygdala are a major pathway for triggering strong behavioral responses to a variety of odorants. However, while this broad mapping has been established, the patterns of amygdala feedback connectivity and the influence on olfactory circuitry remain unknown. Here, using a combination of neuronal tracing approaches, we dissect the connectivity of a cortical amygdala [posteromedial cortical nucleus (PmCo)] feedback circuit innervating the mouse accessory olfactory bulb. Optogenetic activation of PmCo feedback mainly results in feedforward mitral cell (MC) inhibition through direct excitation of GABAergic granule cells. In addition, LED-driven activity of corticofugal afferents increases the gain of MC responses to olfactory nerve stimulation. Thus, through corticofugal pathways, the PmCo likely regulates primary olfactory and social odor processing.
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10
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Pouille F, Schoppa NE. Cannabinoid Receptors Modulate Excitation of an Olfactory Bulb Local Circuit by Cortical Feedback. Front Cell Neurosci 2018; 12:47. [PMID: 29551963 PMCID: PMC5840260 DOI: 10.3389/fncel.2018.00047] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2017] [Accepted: 02/15/2018] [Indexed: 11/16/2022] Open
Abstract
Recent studies have provided evidence that corticofugal feedback (CFF) from the olfactory cortex to the olfactory bulb (OB) can significantly impact the state of excitation of output mitral cells (MCs) and tufted cells (TCs) and also modulate neural synchrony. Interpreting these effects however has been complicated by the large number of cell targets of CFF axons in the bulb. Within the granule cell layer (GCL) alone, CFF axons target both GABAergic granule cells (GCs) as well as GABAergic deep short-axon cells (dSACs) that inhibit GCs. Because GCs are a major source of inhibition of MCs/TCs, CFF could be inhibitory to MCs (by exciting GCs) or disinhibitory (by exciting dSACs that inhibit GCs). In this study, we used patch-clamp recordings combined with optogenetic and electrical stimulation methods to investigate the role of presynaptic cannabinoid receptors in regulating CFF pathways, which could alter the weights of inhibition and disinhibition. Recording first from dSACs, we found that the cannabinoid receptor (CB-R) agonist WIN-55212.2 (WIN) reduced excitatory post-synaptic currents (CFF-EPSCs) driven by stimulation of CFF axons. The effects were reversed by the Type 1 CB-R (CB1-R)-specific antagonist SR-141716A. Furthermore, prolonged 5-s depolarizations applied to postsynaptic dSACs effectively reduced CFF-EPSCs in a CB1-R-dependent fashion, providing evidence for depolarization-induced suppression of excitation (DSE) at CFF-to-dSAC synapses. Further analysis indicated that CB1-Rs mediate widespread suppressive effects on synaptic transmission, occurring at CFF synapses onto different dSAC subtypes and CFF synapses onto GCs. Feedforward excitation of dSACs, mediated by MCs/TCs, however, was not impacted by CB1-Rs. In recordings from MCs, performed to examine the net effect of CB1-R activation on GC-to-MC transmission, we found that WIN could both increase and decrease disynaptic inhibition evoked by CFF axon stimulation. The exact effect depended on the size of the inhibitory response, reflecting the local balance of dSAC vs. GC activation. Our results taken together indicate that CB1-Rs can bidirectionally alter the weighting of inhibition and disinhibition of MCs through their effects on CFF pathways.
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Affiliation(s)
- Frederic Pouille
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Nathan E Schoppa
- Department of Physiology and Biophysics, University of Colorado Anschutz Medical Campus, Aurora, CO, United States.,Neuroscience Program, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
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11
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Mazo C, Grimaud J, Shima Y, Murthy VN, Lau CG. Distinct projection patterns of different classes of layer 2 principal neurons in the olfactory cortex. Sci Rep 2017; 7:8282. [PMID: 28811534 PMCID: PMC5558010 DOI: 10.1038/s41598-017-08331-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 07/07/2017] [Indexed: 11/16/2022] Open
Abstract
The broadly-distributed, non-topographic projections to and from the olfactory cortex may suggest a flat, non-hierarchical organization in odor information processing. Layer 2 principal neurons in the anterior piriform cortex (APC) can be divided into 2 subtypes: semilunar (SL) and superficial pyramidal (SP) cells. Although it is known that SL and SP cells receive differential inputs from the olfactory bulb (OB), little is known about their projections to other olfactory regions. Here, we examined axonal projections of SL and SP cells using a combination of mouse genetics and retrograde labeling. Retrograde tracing from the OB or posterior piriform cortex (PPC) showed that the APC projects to these brain regions mainly through layer 2b cells, and dual-labeling revealed many cells extending collaterals to both target regions. Furthermore, a transgenic mouse line specifically labeling SL cells showed that they send profuse axonal projections to olfactory cortical areas, but not to the OB. These findings support a model in which information flow from SL to SP cells and back to the OB is mediated by a hierarchical feedback circuit, whereas both SL and SP cells broadcast information to higher olfactory areas in a parallel manner.
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Affiliation(s)
- Camille Mazo
- Department of Molecular and Cellular Biology and Center for Brain Science, Harvard University, Cambridge, MA, USA.,Ecole Normale Supérieure de Cachan, Université Paris-Saclay, F-94235, Cachan, France
| | - Julien Grimaud
- Department of Molecular and Cellular Biology and Center for Brain Science, Harvard University, Cambridge, MA, USA.,Ecole Normale Supérieure de Cachan, Université Paris-Saclay, F-94235, Cachan, France
| | - Yasuyuki Shima
- Department of Biology, Brandeis University, Waltham, MA, 02454, USA
| | - Venkatesh N Murthy
- Department of Molecular and Cellular Biology and Center for Brain Science, Harvard University, Cambridge, MA, USA.
| | - C Geoffrey Lau
- Department of Molecular and Cellular Biology and Center for Brain Science, Harvard University, Cambridge, MA, USA. .,Department of Biomedical Sciences and Centre for Biosystems, Neuroscience and Nanotechnology, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong, Hong Kong.
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12
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Ford NC, Griff ER. Steady-state centrifugal input via the lateral olfactory tract modulates spontaneous activity in the rat main olfactory bulb. Neuroscience 2017; 348:165-179. [PMID: 28215749 DOI: 10.1016/j.neuroscience.2017.02.013] [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: 07/08/2016] [Revised: 01/19/2017] [Accepted: 02/08/2017] [Indexed: 12/01/2022]
Abstract
Mitral and tufted cells in the main olfactory bulb (MOB) of anesthetized rats exhibit vigorous spontaneous activity, action potentials produced in the absence of odor stimuli. The central hypothesis of this paper is that tonic activity of centrifugal input to the MOB modulates the spontaneous activity of MOB neurons. The spontaneous activity of centrifugal fibers causes a baseline of steady-state neurotransmitter release, and odor stimulation produces transient changes in the resulting spontaneous activity. This study evaluated the effect of blocking centrifugal axon conduction in the lateral olfactory tract (LOT) by topically applying 2% lidocaine. Mean spontaneous activity of single bulbar neurons was recorded in each MOB layer before and after lidocaine application. While the spontaneous activity of most MOB neurons reversibly decreased after blockade of the LOT, the spontaneous activity of some neurons in the mitral, tufted and granule cell layers increased. The possible mechanisms producing such changes in spontaneous activity are discussed in terms of the tonic, steady-state release of excitatory and/or inhibitory signals from centrifugal inputs to the MOB. The data show for the first time that tonic centrifugal input to the MOB modulates the spontaneous activity of MOB interneurons and projection neurons. The present study is one of the few that focuses on steady-state spontaneous activity. The modulation of spontaneous activity demonstrated in this study implies a behaviorally relevant, state-dependent regulation of the MOB by the CNS.
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Affiliation(s)
- Neil C Ford
- Department of Biological Sciences, University of Cincinnati, P.O. Box 210006, Cincinnati, OH 45221, USA.
| | - Edwin R Griff
- Department of Biological Sciences, University of Cincinnati, P.O. Box 210006, Cincinnati, OH 45221, USA
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13
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Yamaguchi M. Functional Sub-Circuits of the Olfactory System Viewed from the Olfactory Bulb and the Olfactory Tubercle. Front Neuroanat 2017; 11:33. [PMID: 28443001 PMCID: PMC5387040 DOI: 10.3389/fnana.2017.00033] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2016] [Accepted: 03/29/2017] [Indexed: 11/13/2022] Open
Abstract
Understanding of the olfactory neural circuits has progressed beyond analysis of how odor information from the external environment is processed in the brain. While spatially-organized sub-circuits were found to exist up to the olfactory bulb (OB), the arrangement in the olfactory cortex (OC), especially in its representative piriform cortex (PC), appears diffuse and dispersed. An emerging view is that the activity of OC neurons may not simply encode odor identity but rather encode plastic odor information such as odor value. Although many studies support this notion, odor value can be either positive or negative, and the existence of sub-circuits corresponding to individual value types is not well explored. To address this question, I introduce here two olfactory areas other than the PC, OB and olfactory tubercle (OT) whose analysis may facilitate understanding of functional sub-circuits related to different odor values. Peripheral and centrifugal inputs to the OB are considered to relate to odor identity and odor value, respectively and centrifugal inputs to the OB potentially represent different odor values during different behavioral periods. The OT has spatially-segregated functional domains related to distinct motivated and hedonic behaviors. Thus, the OT provides a good starting point from which functional sub-circuits across various olfactory regions can be traced. Further analysis across wide areas of the olfactory system will likely reveal the functional sub-circuits that link odor identity with distinct odor values and direct distinct odor-induced motivated and hedonic behaviors.
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Affiliation(s)
- Masahiro Yamaguchi
- Department of Physiology, Kochi Medical School, Kochi UniversityKochi, Japan
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14
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Affiliation(s)
- Anne Tromelin
- CNRS; UMR6265 Centre des Sciences du Goût et de l'Alimentation; F-21000 Dijon France
- INRA; UMR1324 Centre des Sciences du Goût et de l'Alimentation; F-21000 Dijon France
- Université de Bourgogne; UMR Centre des Sciences du Goût et de l'Alimentation; F-21000 Dijon France
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15
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Otazu GH, Chae H, Davis MB, Albeanu DF. Cortical Feedback Decorrelates Olfactory Bulb Output in Awake Mice. Neuron 2015; 86:1461-77. [PMID: 26051422 DOI: 10.1016/j.neuron.2015.05.023] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 02/21/2015] [Accepted: 05/07/2015] [Indexed: 11/29/2022]
Abstract
The olfactory bulb receives rich glutamatergic projections from the piriform cortex. However, the dynamics and importance of these feedback signals remain unknown. Here, we use multiphoton calcium imaging to monitor cortical feedback in the olfactory bulb of awake mice and further probe its impact on the bulb output. Responses of feedback boutons were sparse, odor specific, and often outlasted stimuli by several seconds. Odor presentation either enhanced or suppressed the activity of boutons. However, any given bouton responded with stereotypic polarity across multiple odors, preferring either enhancement or suppression. Feedback representations were locally diverse and differed in dynamics across bulb layers. Inactivation of piriform cortex increased odor responsiveness and pairwise similarity of mitral cells but had little impact on tufted cells. We propose that cortical feedback differentially impacts these two output channels of the bulb by specifically decorrelating mitral cell responses to enable odor separation.
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Affiliation(s)
- Gonzalo H Otazu
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Honggoo Chae
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Martin B Davis
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
| | - Dinu F Albeanu
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA; Watson School of Biological Sciences, Cold Spring Harbor, NY 11724, USA.
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16
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Rapid induction of granule cell elimination in the olfactory bulb by noxious stimulation in mice. Neurosci Lett 2015; 598:6-11. [DOI: 10.1016/j.neulet.2015.05.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2015] [Revised: 04/21/2015] [Accepted: 05/01/2015] [Indexed: 11/23/2022]
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17
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Brain processing of a configural vs elemental odor mixture in the newborn rabbit. Brain Struct Funct 2015; 221:2527-39. [DOI: 10.1007/s00429-015-1055-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 04/30/2015] [Indexed: 10/23/2022]
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18
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Nunez-Parra A, Li A, Restrepo D. Coding odor identity and odor value in awake rodents. PROGRESS IN BRAIN RESEARCH 2015; 208:205-22. [PMID: 24767484 DOI: 10.1016/b978-0-444-63350-7.00008-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
In the last decade, drastic changes in the understanding of the role of the olfactory bulb and piriform cortex in odor detection have taken place through awake behaving recording in rodents. It is clear that odor responses in mitral and granule cells are strikingly different in the olfactory bulb of anesthetized versus awake animals. In addition, sniff recording has evidenced that mitral cell responses to odors during the sniff can convey information on the odor identity and sniff phase. Moreover, we review studies that show that the mitral cell conveys information on not only odor identity but also whether the odor is rewarded or not (odor value). Finally, we discuss how the substantial increase in awake behaving recording raises questions for future studies.
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Affiliation(s)
- Alexia Nunez-Parra
- Department of Cell and Developmental Biology, Rocky Mountain Taste and Smell Center and Neuroscience Program, University of Colorado Medical School, Aurora, CO, USA
| | - Anan Li
- Department of Cell and Developmental Biology, Rocky Mountain Taste and Smell Center and Neuroscience Program, University of Colorado Medical School, Aurora, CO, USA; State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, The Chinese Academy of Sciences, Wuhan, China
| | - Diego Restrepo
- Department of Cell and Developmental Biology, Rocky Mountain Taste and Smell Center and Neuroscience Program, University of Colorado Medical School, Aurora, CO, USA.
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19
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Boyd AM, Kato HK, Komiyama T, Isaacson JS. Broadcasting of cortical activity to the olfactory bulb. Cell Rep 2015; 10:1032-9. [PMID: 25704808 DOI: 10.1016/j.celrep.2015.01.047] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 12/19/2014] [Accepted: 01/17/2015] [Indexed: 10/24/2022] Open
Abstract
Odor representations are initially formed in the olfactory bulb, which contains a topographic glomerular map of odor molecular features. The bulb transmits sensory information directly to piriform cortex, where it is encoded by distributed ensembles of pyramidal cells without spatial order. Intriguingly, piriform cortex pyramidal cells project back to the bulb, but the information contained in this feedback projection is unknown. Here, we use imaging in awake mice to directly monitor activity in the presynaptic boutons of cortical feedback fibers. We show that the cortex provides the bulb with a rich array of information for any individual odor and that cortical feedback is dependent on brain state. In contrast to the stereotyped, spatial arrangement of olfactory bulb glomeruli, cortical inputs tuned to different odors commingle and indiscriminately target individual glomerular channels. Thus, the cortex modulates early odor representations by broadcasting sensory information diffusely onto spatially ordered bulbar circuits.
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Affiliation(s)
- Alison M Boyd
- Center for Neural Circuits and Behavior and Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Hiroyuki K Kato
- Center for Neural Circuits and Behavior and Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Takaki Komiyama
- Center for Neural Circuits and Behavior and Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA; Neurobiology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA; JST, PRESTO, University of California, San Diego, La Jolla, CA 92093, USA
| | - Jeffry S Isaacson
- Center for Neural Circuits and Behavior and Department of Neurosciences, University of California, San Diego, La Jolla, CA 92093, USA.
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20
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Rothermel M, Wachowiak M. Functional imaging of cortical feedback projections to the olfactory bulb. Front Neural Circuits 2014; 8:73. [PMID: 25071454 PMCID: PMC4080262 DOI: 10.3389/fncir.2014.00073] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Accepted: 06/12/2014] [Indexed: 11/16/2022] Open
Abstract
Processing of sensory information is substantially shaped by centrifugal, or feedback, projections from higher cortical areas, yet the functional properties of these projections are poorly characterized. Here, we used genetically-encoded calcium sensors (GCaMPs) to functionally image activation of centrifugal projections targeting the olfactory bulb (OB). The OB receives massive centrifugal input from cortical areas but there has been as yet no characterization of their activity in vivo. We focused on projections to the OB from the anterior olfactory nucleus (AON), a major source of cortical feedback to the OB. We expressed GCaMP selectively in AON projection neurons using a mouse line expressing Cre recombinase (Cre) in these neurons and Cre-dependent viral vectors injected into AON, allowing us to image GCaMP fluorescence signals from their axon terminals in the OB. Electrical stimulation of AON evoked large fluorescence signals that could be imaged from the dorsal OB surface in vivo. Surprisingly, odorants also evoked large signals that were transient and coupled to odorant inhalation both in the anesthetized and awake mouse, suggesting that feedback from AON to the OB is rapid and robust across different brain states. The strength of AON feedback signals increased during wakefulness, suggesting a state-dependent modulation of cortical feedback to the OB. Two-photon GCaMP imaging revealed that different odorants activated different subsets of centrifugal AON axons and could elicit both excitation and suppression in different axons, indicating a surprising richness in the representation of odor information by cortical feedback to the OB. Finally, we found that activating neuromodulatory centers such as basal forebrain drove AON inputs to the OB independent of odorant stimulation. Our results point to the AON as a multifunctional cortical area that provides ongoing feedback to the OB and also serves as a descending relay for other neuromodulatory systems.
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Affiliation(s)
- Markus Rothermel
- Brain Institute and Department of Neurobiology and Anatomy, University of Utah Salt Lake City, UT, USA
| | - Matt Wachowiak
- Brain Institute and Department of Neurobiology and Anatomy, University of Utah Salt Lake City, UT, USA
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21
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Martin C, Ravel N. Beta and gamma oscillatory activities associated with olfactory memory tasks: different rhythms for different functional networks? Front Behav Neurosci 2014; 8:218. [PMID: 25002840 PMCID: PMC4066841 DOI: 10.3389/fnbeh.2014.00218] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 05/28/2014] [Indexed: 11/18/2022] Open
Abstract
Olfactory processing in behaving animals, even at early stages, is inextricable from top down influences associated with odor perception. The anatomy of the olfactory network (olfactory bulb, piriform, and entorhinal cortices) and its unique direct access to the limbic system makes it particularly attractive to study how sensory processing could be modulated by learning and memory. Moreover, olfactory structures have been early reported to exhibit oscillatory population activities easy to capture through local field potential recordings. An attractive hypothesis is that neuronal oscillations would serve to “bind” distant structures to reach a unified and coherent perception. In relation to this hypothesis, we will assess the functional relevance of different types of oscillatory activity observed in the olfactory system of behaving animals. This review will focus primarily on two types of oscillatory activities: beta (15–40 Hz) and gamma (60–100 Hz). While gamma oscillations are dominant in the olfactory system in the absence of odorant, both beta and gamma rhythms have been reported to be modulated depending on the nature of the olfactory task. Studies from the authors of the present review and other groups brought evidence for a link between these oscillations and behavioral changes induced by olfactory learning. However, differences in studies led to divergent interpretations concerning the respective role of these oscillations in olfactory processing. Based on a critical reexamination of those data, we propose hypotheses on the functional involvement of beta and gamma oscillations for odor perception and memory.
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Affiliation(s)
- Claire Martin
- Laboratory Imagerie et Modélisation en Neurobiologie et Cancérologie, CNRS UMR 8165, Université Paris Sud, Université Paris Diderot Orsay, France
| | - Nadine Ravel
- Team "Olfaction: Du codage à la mémoire," Centre de Recherche en Neurosciences de Lyon CNRS UMR 5292, INSERM U1028, Université Lyon 1 Lyon, France
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22
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Gire DH, Restrepo D, Sejnowski TJ, Greer C, De Carlos JA, Lopez-Mascaraque L. Temporal processing in the olfactory system: can we see a smell? Neuron 2013; 78:416-32. [PMID: 23664611 PMCID: PMC3694266 DOI: 10.1016/j.neuron.2013.04.033] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/24/2013] [Indexed: 10/26/2022]
Abstract
Sensory processing circuits in the visual and olfactory systems receive input from complex, rapidly changing environments. Although patterns of light and plumes of odor create different distributions of activity in the retina and olfactory bulb, both structures use what appears on the surface similar temporal coding strategies to convey information to higher areas in the brain. We compare temporal coding in the early stages of the olfactory and visual systems, highlighting recent progress in understanding the role of time in olfactory coding during active sensing by behaving animals. We also examine studies that address the divergent circuit mechanisms that generate temporal codes in the two systems, and find that they provide physiological information directly related to functional questions raised by neuroanatomical studies of Ramon y Cajal over a century ago. Consideration of differences in neural activity in sensory systems contributes to generating new approaches to understand signal processing.
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Affiliation(s)
- David H Gire
- Molecular and Cellular Biology, and Center for Brain Science, Harvard University, Cambridge, MA 02138, USA
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23
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McGann JP. Presynaptic inhibition of olfactory sensory neurons: new mechanisms and potential functions. Chem Senses 2013; 38:459-74. [PMID: 23761680 DOI: 10.1093/chemse/bjt018] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Presynaptic inhibition is the suppression of neurotransmitter release from a neuron by inhibitory input onto its presynaptic terminal. In the olfactory system, the primary sensory afferents from the olfactory neuroepithelium to the brain's olfactory bulb are strongly modulated by a presynaptic inhibition that has been studied extensively in brain slices and in vivo. In rodents, this inhibition is mediated by γ-amino butyric acid (GABA) and dopamine released from bulbar interneurons. The specialized GABAergic circuit is now well understood to include a specific subset of GAD65-expressing periglomerular interneurons that stimulate presynaptic GABAB receptors to reduce presynaptic calcium conductance. This inhibition is organized to permit the selective modulation of neurotransmitter release from specific populations of olfactory sensory neurons based on their odorant receptor expression, includes specialized microcircuits to create a tonically active inhibition and a separate feedback inhibition evoked by sensory input, and can be modulated by centrifugal projections from other brain regions. Olfactory nerve output can also be modulated by dopaminergic circuitry, but this literature is more difficult to interpret. Presynaptic inhibition of olfactory afferents may extend their dynamic range but could also create state-dependent or odorant-specific sensory filters on primary sensory representations. New directions exploring this circuit's role in olfactory processing are discussed.
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Affiliation(s)
- John P McGann
- Department of Psychology, Rutgers University, 152 Frelinghuysen Road, Piscataway, NJ 08854, USA.
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24
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Boyd AM, Sturgill JF, Poo C, Isaacson JS. Cortical feedback control of olfactory bulb circuits. Neuron 2012; 76:1161-74. [PMID: 23259951 PMCID: PMC3725136 DOI: 10.1016/j.neuron.2012.10.020] [Citation(s) in RCA: 194] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/09/2012] [Indexed: 12/29/2022]
Abstract
Olfactory cortex pyramidal cells integrate sensory input from olfactory bulb mitral and tufted (M/T) cells and project axons back to the bulb. However, the impact of cortical feedback projections on olfactory bulb circuits is unclear. Here, we selectively express channelrhodopsin-2 in olfactory cortex pyramidal cells and show that cortical feedback projections excite diverse populations of bulb interneurons. Activation of cortical fibers directly excites GABAergic granule cells, which in turn inhibit M/T cells. However, we show that cortical inputs preferentially target short axon cells that drive feedforward inhibition of granule cells. In vivo, activation of olfactory cortex that only weakly affects spontaneous M/T cell firing strongly gates odor-evoked M/T cell responses: cortical activity suppresses odor-evoked excitation and enhances odor-evoked inhibition. Together, these results indicate that although cortical projections have diverse actions on olfactory bulb microcircuits, the net effect of cortical feedback on M/T cells is an amplification of odor-evoked inhibition.
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Affiliation(s)
- Alison M. Boyd
- Center for Neural Circuits and Behavior, Department of Neuroscience, University of California, San Diego, School of Medicine, La Jolla, CA 92093, USA
| | - James F. Sturgill
- Center for Neural Circuits and Behavior, Department of Neuroscience, University of California, San Diego, School of Medicine, La Jolla, CA 92093, USA
| | - Cindy Poo
- Center for Neural Circuits and Behavior, Department of Neuroscience, University of California, San Diego, School of Medicine, La Jolla, CA 92093, USA
| | - Jeffry S. Isaacson
- Center for Neural Circuits and Behavior, Department of Neuroscience, University of California, San Diego, School of Medicine, La Jolla, CA 92093, USA
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25
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Niedworok C, Schwarz I, Ledderose J, Giese G, Conzelmann KK, Schwarz M. Charting Monosynaptic Connectivity Maps by Two-Color Light-Sheet Fluorescence Microscopy. Cell Rep 2012; 2:1375-86. [DOI: 10.1016/j.celrep.2012.10.008] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 08/30/2012] [Accepted: 10/11/2012] [Indexed: 01/09/2023] Open
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26
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Charra R, Datiche F, Gigot V, Schaal B, Coureaud G. Pheromone-induced odor learning modifies Fos expression in the newborn rabbit brain. Behav Brain Res 2012; 237:129-40. [PMID: 23000352 DOI: 10.1016/j.bbr.2012.09.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2012] [Revised: 09/08/2012] [Accepted: 09/13/2012] [Indexed: 12/24/2022]
Abstract
Associative learning contributes crucially to adjust the behavior of neonates to the permanently changing environment. In the European rabbit, the mammary pheromone (MP) excreted in milk triggers sucking behavior in newborns, and additionally promotes very rapid learning of initially neutral odor cues. Such stimuli become then as active as the MP itself to elicit the orocephalic motor responses involved in suckling. In this context, the rabbit is an interesting model to address the question of brain circuits early engaged by learning and memory. Here, we evaluated the brain activation (olfactory bulb and central regions) induced in 4-day-old pups by an odorant (ethyl acetoacetate, EAA) after single pairing with the MP and its subsequent acquired ability to elicit sucking-related behavior (conditioned group) or after mere exposure to EAA alone (unconditioned group). The brain-wide mapping of c-Fos expression was used to compare neural activation patterns in both groups. Evidence of high immunostaining to odorant EAA occurred in the mitral+granule cells layer of the main olfactory bulb in pups previously exposed to EAA in association with the MP. These pups also showed higher expression of Fos in the piriform cortex, the hypothalamic lateral preoptic area and the amygdala (cortical and basal nuclei). Thus, MP-induced odor learning induces rapid brain modifications in rabbit neonates. The cerebral framework supporting the acquisition appears however different compared to the circuit involved in the processing of the MP itself.
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Affiliation(s)
- R Charra
- Developmental Ethology and Cognitive Psychology Group and Brain, Sensoriality and Metabolism Group, Centre des Sciences du Goût et de l'Alimentation, UMR 6265 CNRS, 1324 INRA, Université de Bourgogne, Dijon, France
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27
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Hagiwara A, Pal SK, Sato TF, Wienisch M, Murthy VN. Optophysiological analysis of associational circuits in the olfactory cortex. Front Neural Circuits 2012; 6:18. [PMID: 22529781 PMCID: PMC3329886 DOI: 10.3389/fncir.2012.00018] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 03/26/2012] [Indexed: 02/04/2023] Open
Abstract
Primary olfactory cortical areas receive direct input from the olfactory bulb, but also have extensive associational connections that have been mainly studied with classical anatomical methods. Here, we shed light on the functional properties of associational connections in the anterior and posterior piriform cortices (aPC and pPC) using optophysiological methods. We found that the aPC receives dense functional connections from the anterior olfactory nucleus (AON), a major hub in olfactory cortical circuits. The local recurrent connectivity within the aPC, long invoked in cortical autoassociative models, is sparse and weak. By contrast, the pPC receives negligible input from the AON, but has dense connections from the aPC as well as more local recurrent connections than the aPC. Finally, there are negligible functional connections from the pPC to aPC. Our study provides a circuit basis for a more sensory role for the aPC in odor processing and an associative role for the pPC.
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Affiliation(s)
- Akari Hagiwara
- Akari Hagiwara, Faculty of Medicine, Department of Biochemistry, University of Yamanashi, 1110 Shimokato, Chuo, Yamanashi, 409-3898, Japan. e-mail:
| | | | | | | | - Venkatesh N. Murthy
- Department of Molecular and Cellular Biology, Center for Brain Science, Harvard University, CambridgeMA, USA
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28
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Peng W. Intravenous immunoglobulin treatment on anti-GM1 antibodies associated neuropathies inhibits cholera toxin and galectin-1 binding to ganglioside GM1. Immunol Lett 2012; 143:146-51. [DOI: 10.1016/j.imlet.2012.01.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2011] [Revised: 12/30/2011] [Accepted: 01/13/2012] [Indexed: 12/17/2022]
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29
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Abstract
The olfactory peduncle, the region connecting the olfactory bulb with the basal forebrain, contains several neural areas that have received relatively little attention. The present work includes studies that provide an overview of the region in the mouse. An analysis of cell soma size in pars principalis (pP) of the anterior olfactory nucleus (AON) revealed considerable differences in tissue organization between mice and rats. An unbiased stereological study of neuron number in the cell-dense regions of pars externa (pE) and pP of the AON of 3-, 12-, and 24-month-old mice indicated that pE has about 16,500 cells in 0.043 mm(3) and pP about 58,300 cells in 0.307 mm(3) . Quantitative Golgi studies of pyramidal neurons in pP suggested that mouse neurons are similar to although smaller than those of the rat. An immunohistochemical analysis demonstrated that all peduncular regions (pE, pP, the dorsal peduncular cortex, ventral tenia tecta, and anterior olfactory tubercle and piriform cortex) have cells that express either calbindin, calretinin, parvalbumin, somatostatin, vasoactive intestinal polypeptide, neuropeptide Y, or cholecystokinin (antigens commonly co-expressed by subspecies of γ-aminobutyric acid [GABA]ergic neurons), although the relative numbers of each cell type differ between zones. Finally, an electron microscopic comparison of the organization of myelinated fibers in lateral olfactory tract in the anterior and posterior peduncle indicated that the region is less orderly in mice than in rats. The results provide a caveat for investigators who generalize data between species, as both similarities and differences between the laboratory mouse and rat were observed.
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Affiliation(s)
- Peter C Brunjes
- Department of Psychology, University of Virginia, Charlottesville, Virginia 22904, USA.
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30
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Doucette W, Gire DH, Whitesell J, Carmean V, Lucero MT, Restrepo D. Associative cortex features in the first olfactory brain relay station. Neuron 2011; 69:1176-87. [PMID: 21435561 PMCID: PMC3064824 DOI: 10.1016/j.neuron.2011.02.024] [Citation(s) in RCA: 111] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/12/2011] [Indexed: 11/23/2022]
Abstract
Synchronized firing of mitral cells (MCs) in the olfactory bulb (OB) has been hypothesized to help bind information together in olfactory cortex (OC). In this survey of synchronized firing by suspected MCs in awake, behaving vertebrates, we find the surprising result that synchronized firing conveys information on odor value ("Is it rewarded?") rather than odor identity ("What is the odor?"). We observed that as mice learned to discriminate between odors, synchronous firing responses to the rewarded and unrewarded odors became divergent. Furthermore, adrenergic blockage decreases the magnitude of odor divergence of synchronous trains, suggesting that MCs contribute to decision-making through adrenergic-modulated synchronized firing. Thus, in the olfactory system information on stimulus reward is found in MCs one synapse away from the sensory neuron.
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Affiliation(s)
- Wilder Doucette
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
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