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Coppola DM, Reisert J. The Role of the Stimulus in Olfactory Plasticity. Brain Sci 2023; 13:1553. [PMID: 38002512 PMCID: PMC10669894 DOI: 10.3390/brainsci13111553] [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: 10/18/2023] [Revised: 11/02/2023] [Accepted: 11/02/2023] [Indexed: 11/26/2023] Open
Abstract
Plasticity, the term we use to describe the ability of a nervous system to change with experience, is the evolutionary adaptation that freed animal behavior from the confines of genetic determinism. This capacity, which increases with brain complexity, is nowhere more evident than in vertebrates, especially mammals. Though the scientific study of brain plasticity dates back at least to the mid-19th century, the last several decades have seen unprecedented advances in the field afforded by new technologies. Olfaction is one system that has garnered particular attention in this realm because it is the only sensory modality with a lifelong supply of new neurons, from two niches no less! Here, we review some of the classical and contemporary literature dealing with the role of the stimulus or lack thereof in olfactory plasticity. We have restricted our comments to studies in mammals that have used dual tools of the field: stimulus deprivation and stimulus enrichment. The former manipulation has been implemented most frequently by unilateral naris occlusion and, thus, we have limited our comments to research using this technique. The work reviewed on deprivation provides substantial evidence of activity-dependent processes in both developing and adult mammals at multiple levels of the system from olfactory sensory neurons through to olfactory cortical areas. However, more recent evidence on the effects of deprivation also establishes several compensatory processes with mechanisms at every level of the system, whose function seems to be the restoration of information flow in the face of an impoverished signal. The results of sensory enrichment are more tentative, not least because of the actual manipulation: What odor or odors? At what concentrations? On what schedule? All of these have frequently not been sufficiently rationalized or characterized. Perhaps it is not surprising, then, that discrepant results are common in sensory enrichment studies. Despite this problem, evidence has accumulated that even passively encountered odors can "teach" olfactory cortical areas to better detect, discriminate, and more efficiently encode them for future encounters. We discuss these and other less-established roles for the stimulus in olfactory plasticity, culminating in our recommended "aspirations" for the field going forward.
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Affiliation(s)
- David M. Coppola
- Biology Department, Randolph-Macon College, Ashland, VA 23005, USA
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2
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Muscarinic antagonists impair multiple aspects of operant discrimination learning and performance. Neurosci Lett 2023; 794:137025. [PMID: 36529388 PMCID: PMC9812939 DOI: 10.1016/j.neulet.2022.137025] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 12/12/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022]
Abstract
Acetylcholine signaling can strengthen associations between environmental cues and reward availability. Diverse subtypes (M1-M5) of the muscarinic acetylcholine receptor (mAChR) family may have distinct roles in different learning and memory processes, such as encoding cue-reward associations and consolidating these associations in long-term memory. Using an operant discrimination learning task in which mice are trained to nose poke during a tone to receive a food reward, we found that acquisition of the task requires mAChR signaling in the central nervous system. In addition, post-session injections of a broad mAChR antagonist, scopolamine impaired consolidation of the cue-reward memory. Further, after successful learning of a cue-reward contingency across multiple training sessions, mice that received a single pre-session injection of scopolamine were unable to use the learned cue association to receive rewards. Taken together, these data demonstrate distinct roles for muscarinic signaling in acquisition, consolidation and recall of the operant discrimination learning task. Understanding mechanisms underlying natural reward-related responding may provide insight into other maladaptive forms of reward learning such as addiction.
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3
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Dean B, Bakker G, Ueda HR, Tobin AB, Brown A, Kanaan RAA. A growing understanding of the role of muscarinic receptors in the molecular pathology and treatment of schizophrenia. Front Cell Neurosci 2023; 17:1124333. [PMID: 36909280 PMCID: PMC9992992 DOI: 10.3389/fncel.2023.1124333] [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: 12/15/2022] [Accepted: 02/06/2023] [Indexed: 02/24/2023] Open
Abstract
Pre-clinical models, postmortem and neuroimaging studies all support a role for muscarinic receptors in the molecular pathology of schizophrenia. From these data it was proposed that activation of the muscarinic M1 and/or M4 receptor would reduce the severity of the symptoms of schizophrenia. This hypothesis is now supported by results from two clinical trials which indicate that activating central muscarinic M1 and M4 receptors can reduce the severity of positive, negative and cognitive symptoms of the disorder. This review will provide an update on a growing body of evidence that argues the muscarinic M1 and M4 receptors have critical roles in CNS functions that are dysregulated by the pathophysiology of schizophrenia. This realization has been made possible, in part, by the growing ability to visualize and quantify muscarinic M1 and M4 receptors in the human CNS using molecular neuroimaging. We will discuss how these advances have provided evidence to support the notion that there is a sub-group of patients within the syndrome of schizophrenia that have a unique molecular pathology driven by a marked loss of muscarinic M1 receptors. This review is timely, as drugs targeting muscarinic receptors approach clinical use for the treatment of schizophrenia and here we outline the background biology that supported development of such drugs to treat the disorder.
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Affiliation(s)
- Brian Dean
- Synaptic Biology and Cognition Laboratory, The Florey Institute of Neuroscience and Mental Health, Parkville, VIC, Australia
| | | | - Hiroki R Ueda
- Department of Systems Pharmacology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan.,Laboratory for Synthetic Biology, RIKEN Center for Biosystems Dynamics Research, Osaka, Japan
| | - Andrew B Tobin
- Advanced Research Centre (ARC), School of Molecular Bioscience, University of Glasgow, Glasgow, United Kingdom
| | | | - Richard A A Kanaan
- Department of Psychiatry, Austin Health, The University of Melbourne, Heidelberg, VIC, Australia
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4
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Ahnaou A, Whim D. REM sleep behavior and olfactory dysfunction: improving the utility and translation of animal models in the search for neuroprotective therapies for Parkinson's disease. Neurosci Biobehav Rev 2022; 143:104897. [PMID: 36183864 DOI: 10.1016/j.neubiorev.2022.104897] [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: 05/14/2021] [Revised: 09/19/2022] [Accepted: 09/27/2022] [Indexed: 11/25/2022]
Abstract
Parkinson's disease (PD) is a heterogeneous neurodegenerative disease that belongs to the family of synucleiopathies, varying in age, symptoms and progression. Hallmark of the disease is the accumulation of misfolded α-synuclein protein (α-Syn) in neuronal and non-neuronal brain cells. In past decades, diagnosis and treatment of PD has focused on motor deficits, which for the clinical endpoint, have contributed to the prevalence of deficits in the nigrostriatal dopaminergic system and animal models related to motor behavior to study disease. However, clinical trials have failed to translate results from animal models into effective treatments. PD as a multisystem disorder therefore requires additional assessment of motor and non-motor symptoms. Braak's staging revealed early α-Syn pathology in pontine brainstem and olfactory circuits controlling rapid eye movement sleep behavior disorder (RBD) and olfaction, respectively. Recent converging evidence from multicenter clinical studies supports that RBD is the most important risk factor for prodromal PD and the conduct of neuroprotective therapeutic trials in RBD-enriched cohorts has been recommended. Animal models of RBD and olfaction dysfunction can aid to fill the gap in translational research.
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Affiliation(s)
- A Ahnaou
- Department of Neuroscience, Janssen Research & Development, a Division of Janssen Pharmaceutica NV. Turnhoutseweg 30, B-2340 Beerse, Belgium.
| | - Drinkenburg Whim
- Department of Neuroscience, Janssen Research & Development, a Division of Janssen Pharmaceutica NV. Turnhoutseweg 30, B-2340 Beerse, Belgium
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5
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Zhou P, Liu P, Zhang Y, Wang D, Li A. The Response Dynamics and Function of Cholinergic and GABAergic Neurons in the Basal Forebrain During Olfactory Learning. Front Cell Neurosci 2022; 16:911439. [PMID: 35966196 PMCID: PMC9363711 DOI: 10.3389/fncel.2022.911439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2022] [Accepted: 06/23/2022] [Indexed: 11/13/2022] Open
Abstract
Modulation of neural circuits is essential for flexible sensory perception and decision-making in a changing environment. Cholinergic and GABAergic projections to the olfactory system from the horizontal limb of the diagonal band of Broca (HDB) in the basal forebrain are crucial for odor detection and olfactory learning. Although studies have demonstrated that HDB neurons respond during olfactory learning, how cholinergic and GABAergic neurons differ in their response dynamics and roles in olfactory learning remains unclear. In this study, we examined the response profiles of these two subpopulations of neurons during passive odor exposure and associative olfactory learning. We show that the excitatory responses in both cholinergic and GABAergic neurons tended to habituate during repeated passive odor exposure. However, while these habituated responses were also observed in GABAergic neurons during a go-go task, there was no such habituation in cholinergic neurons. Moreover, the responses to S+ and S− trials diverged in cholinergic neurons once mice learned a go/no-go task. Furthermore, the chemogenetic inactivation of cholinergic neurons in the HDB impaired odor discrimination. Together, these findings suggest that cholinergic neurons in the HDB reflect attention to positive reinforcement and may regulate odor discrimination via top–down inputs to the olfactory system.
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Affiliation(s)
| | | | | | | | - Anan Li
- *Correspondence: Dejuan Wang Anan Li
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6
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Huoman J, Sayyab S, Apostolou E, Karlsson L, Porcile L, Rizwan M, Sharma S, Das J, Rosén A, Lerm M. Epigenetic rewiring of pathways related to odour perception in immune cells exposed to SARS-CoV-2 in vivo and in vitro. Epigenetics 2022; 17:1875-1891. [PMID: 35758003 PMCID: PMC9665140 DOI: 10.1080/15592294.2022.2089471] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
A majority of SARS-CoV-2 recoverees develop only mild-to-moderate symptoms, while some remain completely asymptomatic. Although viruses, including SARS-CoV-2, may evade host immune responses by epigenetic mechanisms including DNA methylation, little is known about whether these modifications are important in defence against and healthy recovery from COVID-19 in the host. To this end, epigenome-wide DNA methylation patterns from COVID-19 convalescents were compared to uninfected controls from before and after the pandemic. Peripheral blood mononuclear cell (PBMC) DNA was extracted from uninfected controls, COVID-19 convalescents, and symptom-free individuals with SARS-CoV-2-specific T cell-responses, as well as from PBMCs stimulated in vitro with SARS-CoV-2. Subsequently, the Illumina MethylationEPIC 850K array was performed, and statistical/bioinformatic analyses comprised differential DNA methylation, pathway over-representation, and module identification analyses. Differential DNA methylation patterns distinguished COVID-19 convalescents from uninfected controls, with similar results in an experimental SARS-CoV-2 infection model. A SARS-CoV-2-induced module was identified in vivo, comprising 66 genes of which six (TP53, INS, HSPA4, SP1, ESR1, and FAS) were present in corresponding in vitro analyses. Over-representation analyses revealed involvement in Wnt, muscarinic acetylcholine receptor signalling, and gonadotropin-releasing hormone receptor pathways. Furthermore, numerous differentially methylated and network genes from both settings interacted with the SARS-CoV-2 interactome. Altered DNA methylation patterns of COVID-19 convalescents suggest recovery from mild-to-moderate SARS-CoV-2 infection leaves longstanding epigenetic traces. Both in vitro and in vivo exposure caused epigenetic modulation of pathways thataffect odour perception. Future studies should determine whether this reflects host-induced protective antiviral defense or targeted viral hijacking to evade host defence.
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Affiliation(s)
- Johanna Huoman
- Division of Inflammation and Infection, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden.,Department of Dermatology and Allergy, University Hospital Bonn, Bonn, Germany
| | - Shumaila Sayyab
- Division of Inflammation and Infection, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Eirini Apostolou
- Division of Cell Biology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Lovisa Karlsson
- Division of Inflammation and Infection, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Lucas Porcile
- Division of Inflammation and Infection, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Muhammad Rizwan
- Division of Cell Biology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Sumit Sharma
- Division of Molecular Medicine and Virology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Jyotirmoy Das
- Division of Inflammation and Infection, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Anders Rosén
- Division of Cell Biology, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
| | - Maria Lerm
- Division of Inflammation and Infection, Department of Biomedical and Clinical Sciences, Linköping University, Linköping, Sweden
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7
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De Saint Jan D. Target-specific control of olfactory bulb periglomerular cells by GABAergic and cholinergic basal forebrain inputs. eLife 2022; 11:71965. [PMID: 35225232 PMCID: PMC8901171 DOI: 10.7554/elife.71965] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Accepted: 02/16/2022] [Indexed: 11/13/2022] Open
Abstract
The olfactory bulb (OB), the first relay for odor processing in the brain, receives dense GABAergic and cholinergic long-range projections from basal forebrain (BF) nuclei that provide information about the internal state and behavioral context of the animal. However, the targets, impact, and dynamic of these afferents are still unclear. How BF synaptic inputs modulate activity in diverse subtypes of periglomerular (PG) interneurons using optogenetic stimulation and loose cell-attached or whole-cell patch-clamp recording in OB slices from adult mice were studied in this article. GABAergic BF inputs potently blocked PG cells firing except in a minority of calretinin-expressing cells in which GABA release elicited spiking. Parallel cholinergic projections excited a previously overlooked PG cell subtype via synaptic activation of M1 muscarinic receptors. Low-frequency stimulation of the cholinergic axons drove persistent firing in these PG cells, thereby increasing tonic inhibition in principal neurons. Taken together, these findings suggest that modality-specific BF inputs can orchestrate synaptic inhibition in OB glomeruli using multiple, potentially independent, inhibitory or excitatory target-specific pathways.
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Affiliation(s)
- Didier De Saint Jan
- Institut des Neurosciences Cellulaires et Intégratives, Centre National de la Recherche Scientifique, Strasbourg, France
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8
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Ahnaou A, Chave L, Manyakov NV, Drinkenburg WHIM. Odour Retrieval Processing in Mice: Cholinergic Modulation of Oscillatory Coupling in Olfactory Bulb-Piriform Networks. Neuropsychobiology 2022; 80:374-392. [PMID: 33588406 DOI: 10.1159/000513511] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Accepted: 11/26/2020] [Indexed: 11/19/2022]
Abstract
BACKGROUND/AIMS Olfactory dysfunction can provide valuable insight into early pathophysiological processes of brain disorders. Olfactory processing of chemosensory and odour sensitivity relies on segregating salient odours from background odours cues. Odour-evoked fast oscillations in the olfactory bulb (OB) are hypothesized to be an important index of odour quality coding. The present preclinical work aimed at better understanding connectivity associated with odour coding and behavioural odour discrimination. METHODS Network oscillations and functional connectivity (FC) were measured in C57BL/6 mice performing the olfactory associative odour learning (OL) test, using multichannel local field potential recordings in key olfactory networks. Cholinergic modulation of odour processing was investigated using the muscarinic antagonist scopolamine. RESULTS At the behavioural level, olfactory memory, which refers to the acquisition and recollection of a reference odour by reduced exploration time, was observed in animals that correctly learned the task. Significant decrease in mean investigation and retrieval time of the associated odour-food reward was observed between trials. At the network level, the associated odour during sniffing behaviour was associated with enhanced coherence in the β and γ frequency oscillations across the olfactory pathway, with marked changes observed between the OB and anterior piriform cortex (PC). The enhanced phase-amplitude cross-frequency coupling in the OB and the weak coupling index in the hippocampal CA1 suggests a role of the OB network in olfaction encoding and processing. Scopolamine impaired behavioural and FC underlying recall and retrieval of the associated odour. CONCLUSION The results suggest that the acquisition and formation of odour reference memory rely primarily on FC at the OB-PC network and confirm the role of muscarinic receptors in olfactory retrieval processing.
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Affiliation(s)
- Abdallah Ahnaou
- Department of Neuroscience, Janssen Research & Development, a Division of Janssen Pharmaceutica NV, Beerse, Belgium,
| | - Lucile Chave
- Department of Neuroscience, Janssen Research & Development, a Division of Janssen Pharmaceutica NV, Beerse, Belgium
| | - Nikolay V Manyakov
- Department of Neuroscience, Janssen Research & Development, a Division of Janssen Pharmaceutica NV, Beerse, Belgium
| | - Wilhelmus H I M Drinkenburg
- Department of Neuroscience, Janssen Research & Development, a Division of Janssen Pharmaceutica NV, Beerse, Belgium
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9
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Toscano-Márquez B, Oboti L, Harvey-Girard E, Maler L, Krahe R. Distribution of the cholinergic nuclei in the brain of the weakly electric fish, Apteronotus leptorhynchus: Implications for sensory processing. J Comp Neurol 2020; 529:1810-1829. [PMID: 33089503 DOI: 10.1002/cne.25058] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 10/14/2020] [Accepted: 10/15/2020] [Indexed: 12/15/2022]
Abstract
Acetylcholine acts as a neurotransmitter/neuromodulator of many central nervous system processes such as learning and memory, attention, motor control, and sensory processing. The present study describes the spatial distribution of cholinergic neurons throughout the brain of the weakly electric fish, Apteronotus leptorhynchus, using in situ hybridization of choline acetyltransferase mRNA. Distinct groups of cholinergic cells were observed in the telencephalon, diencephalon, mesencephalon, and hindbrain. These included cholinergic cell groups typically identified in other vertebrate brains, for example, motor neurons. Using both in vitro and ex vivo neuronal tracing methods, we identified two new cholinergic connections leading to novel hypotheses on their functional significance. Projections to the nucleus praeeminentialis (nP) arise from isthmic nuclei, possibly including the nucleus lateralis valvulae (nLV) and the isthmic nucleus (nI). The nP is a central component of all electrosensory feedback pathways to the electrosensory lateral line lobe (ELL). We have previously shown that some neurons in nP, TS, and tectum express muscarinic receptors. We hypothesize that, based on nLV/nI cell responses in other teleosts and isthmic connectivity in A. leptorhynchus, the isthmic connections to nP, TS, and tectum modulate responses to electrosensory and/or visual motion and, in particular, to looming/receding stimuli. In addition, we found that the octavolateral efferent (OE) nucleus is the likely source of cholinergic fibers innervating the ELL. In other teleosts, OE inhibits octavolateral hair cells during locomotion. In gymnotiform fish, OE may also act on the first central processing stage and, we hypothesize, implement corollary discharge modulation of electrosensory processing during locomotion.
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Affiliation(s)
| | - Livio Oboti
- Humboldt-Universität zu Berlin, Institut für Biologie, Berlin, Germany
| | - Erik Harvey-Girard
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Leonard Maler
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Rüdiger Krahe
- Department of Biology, McGill University, Montreal, Quebec.,Humboldt-Universität zu Berlin, Institut für Biologie, Berlin, Germany
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Kouremenou I, Piper M, Zalucki O. Adult Neurogenesis in the Olfactory System: Improving Performance for Difficult Discrimination Tasks? Bioessays 2020; 42:e2000065. [PMID: 32767425 DOI: 10.1002/bies.202000065] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Revised: 07/17/2020] [Indexed: 02/04/2023]
Abstract
What is the function of new neurons entering the olfactory bulb? Many insights regarding the molecular control of adult neurogenesis have been uncovered, but the purpose of new neurons entering the olfactory bulb has been difficult to ascertain. Here, studies investigating the role of adult neurogenesis in olfactory discrimination in mice are reviewed. Studies in which adult neurogenesis is affected are highlighted, with a focus on the role of environment enrichment and what happens during ageing. There is evidence for a role of adult neurogenesis in fine discrimination tasks, as underscored by studies that enhance adult neurogenesis. This is also observed in ageing studies, where older mice with reduced levels of adult neurogenesis perform poorly in olfactory discrimination. Differences in methodology that could account for alternative conclusions, and the importance of specificity in methods being used to investigate the effect of adult neurogenesis in olfactory performance are emphasized.
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Affiliation(s)
- Ioanna Kouremenou
- The School of Biomedical Sciences, The University of Queensland, Brisbane, 4072, Australia
| | - Michael Piper
- The School of Biomedical Sciences, The University of Queensland, Brisbane, 4072, Australia.,Queensland Brain Institute, The University of Queensland, Brisbane, 4072, Australia
| | - Oressia Zalucki
- The School of Biomedical Sciences, The University of Queensland, Brisbane, 4072, Australia
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11
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Blount A, Coppola DM. The effect of odor enrichment on olfactory acuity: Olfactometric testing in mice using two mirror-molecular pairs. PLoS One 2020; 15:e0233250. [PMID: 32730274 PMCID: PMC7392274 DOI: 10.1371/journal.pone.0233250] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 07/13/2020] [Indexed: 12/17/2022] Open
Abstract
Intelligent systems in nature like the mammalian nervous system benefit from adaptable inputs that can tailor response profiles to their environment that varies in time and space. Study of such plasticity, in all its manifestations, forms a pillar of classical and modern neuroscience. This study is concerned with a novel form of plasticity in the olfactory system referred to as induction. In this process, subjects unable to smell a particular odor, or unable to differentiate similar odors, gain these abilities through mere exposure to the odor(s) over time without the need for attention or feedback (reward or punishment). However, few studies of induction have rigorously documented changes in olfactory threshold for the odor(s) used for "enrichment." We trained 36 CD-1 mice in an operant-olfactometer (go/no go task) to discriminate a mixture of stereoisomers from a lone stereoisomer using two enantiomeric pairs: limonene and carvone. We also measured each subject's ability to detect one of the stereoisomers of each odor. In order to assess the effect of odor enrichment on enantiomer discrimination and detection, mice were exposed to both stereoisomers of limonene or carvone for 2 to 12 weeks. Enrichment was effected by adulterating a subject's food (passive enrichment) with one pair of enantiomers or by exposing a subject to the enantiomers in daily operant discrimination testing (active enrichment). We found that neither form of enrichment altered discrimination nor detection. And this result pertained using either within-subject or between-subject experimental designs. Unexpectedly, our threshold measurements were among the lowest ever recorded for any species, which we attributed to the relatively greater amount of practice (task replication) we allowed our mice compared to other reports. Interestingly, discrimination thresholds were no greater (limonene) or only modestly greater (carvone) from detection thresholds suggesting chiral-specific olfactory receptors determine thresholds for these compounds. The super-sensitivity of mice, shown in this study, to the limonene and carvone enantiomers, compared to the much lesser acuity of humans for these compounds, reported elsewhere, may resolve the mystery of why the former group with four-fold more olfactory receptors have tended, in previous studies, to have similar thresholds to the latter group. Finally, our results are consistent with the conclusion that supervised-perceptual learning i.e. that involving repeated feedback for correct and incorrect decisions, rather than induction, is the form of plasticity that allows animals to fully realize the capabilities of their olfactory system.
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Affiliation(s)
- Alyson Blount
- Department of Biology, Randolph-Macon College, Ashland, Virginia, United States of America
| | - David M. Coppola
- Department of Biology, Randolph-Macon College, Ashland, Virginia, United States of America
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12
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Vaucher E, Laliberté G, Higgins MC, Maheux M, Jolicoeur P, Chamoun M. Cholinergic potentiation of visual perception and vision restoration in rodents and humans. Restor Neurol Neurosci 2020; 37:553-569. [PMID: 31839615 DOI: 10.3233/rnn-190947] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
BACKGROUND The cholinergic system is a potent neuromodulator system that plays a critical role in cortical plasticity, attention, and learning. Recently, it was found that boosting this system during perceptual learning robustly enhances sensory perception in rodents. In particular, pairing cholinergic activation with visual stimulation increases neuronal responses, cue detection ability, and long-term facilitation in the primary visual cortex. The mechanisms of cholinergic enhancement are closely linked to attentional processes, long-term potentiation, and modulation of the excitatory/inhibitory balance. Some studies currently examine this effect in humans. OBJECTIVE The present article reviews the research from our laboratory, examining whether potentiating the central cholinergic system could help visual perception and restoration. METHODS Electrophysiological or pharmacological enhancement of the cholinergic system are administered during a visual training. Electrophysiological responses and perceptual learning performance are investigated before and after the training in rats and humans. This approach's ability to restore visual capacities following a visual deficit induced by a partial optic nerve crush is also investigated in rats. RESULTS The coupling of visual training to cholinergic stimulation improved visual discrimination and visual acuity in rats, and improved residual vision after a deficit. These changes were due to muscarinic and nicotinic transmissions and were associated with a functional improvement of evoked potentials. In humans, potentiation of cholinergic transmission with 5 mg of donepezil showed improved learning and ocular dominance plasticity, although this treatment was ineffective in augmenting the perceptual threshold and electroencephalography. CONCLUSIONS Potential therapeutic outcomes ought to facilitate vision restoration using commercially available cholinergic agents combined with visual stimulation in order to prevent irreversible vision loss in patients. This approach has the potential to help a large population of visually impaired individuals.
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Affiliation(s)
- Elvire Vaucher
- Laboratoire de Neurobiologie de la Cognition Visuelle, École d'optométrie, Université de Montréal, Montréal, Québec, Canada.,Centre de recherche en neuropsychologie et cognition (CERNEC), Montréal, Québec, Canada
| | - Guillaume Laliberté
- Laboratoire de Neurobiologie de la Cognition Visuelle, École d'optométrie, Université de Montréal, Montréal, Québec, Canada
| | - Marie-Charlotte Higgins
- Laboratoire de Neurobiologie de la Cognition Visuelle, École d'optométrie, Université de Montréal, Montréal, Québec, Canada
| | - Manon Maheux
- Centre de recherche en neuropsychologie et cognition (CERNEC), Montréal, Québec, Canada.,Département de Psychologie, Université de Montréal, Montréal, Québec, Canada
| | - Pierre Jolicoeur
- Centre de recherche en neuropsychologie et cognition (CERNEC), Montréal, Québec, Canada.,Département de Psychologie, Université de Montréal, Montréal, Québec, Canada
| | - Mira Chamoun
- Laboratoire de Neurobiologie de la Cognition Visuelle, École d'optométrie, Université de Montréal, Montréal, Québec, Canada
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13
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Yang D, Ding C, Qi G, Feldmeyer D. Cholinergic and Adenosinergic Modulation of Synaptic Release. Neuroscience 2020; 456:114-130. [PMID: 32540364 DOI: 10.1016/j.neuroscience.2020.06.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 05/29/2020] [Accepted: 06/01/2020] [Indexed: 01/14/2023]
Abstract
In this review we will discuss the effect of two neuromodulatory transmitters, acetylcholine (ACh) and adenosine, on the synaptic release probability and short-term synaptic plasticity. ACh and adenosine differ fundamentally in the way they are released into the extracellular space. ACh is released mostly from synaptic terminals and axonal bouton of cholinergic neurons in the basal forebrain (BF). Its mode of action on synaptic release probability is complex because it activate both ligand-gated ion channels, so-called nicotinic ACh receptors and G-protein coupled muscarinic ACh receptors. In contrast, adenosine is released from both neurons and glia via nucleoside transporters or diffusion over the cell membrane in a non-vesicular, non-synaptic fashion; its receptors are exclusively G-protein coupled receptors. We show that ACh and adenosine effects are highly specific for an identified synaptic connection and depend mostly on the presynaptic but also on the postsynaptic receptor type and discuss the functional implications of these differences.
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Affiliation(s)
- Danqing Yang
- Research Centre Juelich, Institute of Neuroscience and Medicine 10, Leo-Brandt-Strasse, Juelich, Germany
| | - Chao Ding
- Research Centre Juelich, Institute of Neuroscience and Medicine 10, Leo-Brandt-Strasse, Juelich, Germany
| | - Guanxiao Qi
- Research Centre Juelich, Institute of Neuroscience and Medicine 10, Leo-Brandt-Strasse, Juelich, Germany
| | - Dirk Feldmeyer
- Research Centre Juelich, Institute of Neuroscience and Medicine 10, Leo-Brandt-Strasse, Juelich, Germany; RWTH Aachen University Hospital, Pauwelsstrasse 30, Aachen, Germany; Jülich-Aachen Research Alliance Brain - JARA Brain, Germany.
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14
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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 DOI: 10.1111/apha.13333] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [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 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 China
| | - Yang Zhou
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology Xuzhou Medical University Xuzhou China
| | - Diego Restrepo
- Department of Cell and Developmental Biology University of Colorado Anschutz Medical Campus Aurora Colorado
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15
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Gulinello M, Mitchell HA, Chang Q, Timothy O'Brien W, Zhou Z, Abel T, Wang L, Corbin JG, Veeraragavan S, Samaco RC, Andrews NA, Fagiolini M, Cole TB, Burbacher TM, Crawley JN. Rigor and reproducibility in rodent behavioral research. Neurobiol Learn Mem 2019; 165:106780. [PMID: 29307548 PMCID: PMC6034984 DOI: 10.1016/j.nlm.2018.01.001] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 12/22/2017] [Accepted: 01/03/2018] [Indexed: 01/08/2023]
Abstract
Behavioral neuroscience research incorporates the identical high level of meticulous methodologies and exacting attention to detail as all other scientific disciplines. To achieve maximal rigor and reproducibility of findings, well-trained investigators employ a variety of established best practices. Here we explicate some of the requirements for rigorous experimental design and accurate data analysis in conducting mouse and rat behavioral tests. Novel object recognition is used as an example of a cognitive assay which has been conducted successfully with a range of methods, all based on common principles of appropriate procedures, controls, and statistics. Directors of Rodent Core facilities within Intellectual and Developmental Disabilities Research Centers contribute key aspects of their own novel object recognition protocols, offering insights into essential similarities and less-critical differences. Literature cited in this review article will lead the interested reader to source papers that provide step-by-step protocols which illustrate optimized methods for many standard rodent behavioral assays. Adhering to best practices in behavioral neuroscience will enhance the value of animal models for the multiple goals of understanding biological mechanisms, evaluating consequences of genetic mutations, and discovering efficacious therapeutics.
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Affiliation(s)
- Maria Gulinello
- IDDRC Behavioral Core Facility, Neuroscience Department, Albert Einstein College of Medicine, Bronx, NY 10461, USA
| | - Heather A Mitchell
- IDD Models Core, Waisman Center, University of Wisconsin Madison, Madison, WI 53705, USA
| | - Qiang Chang
- IDD Models Core, Waisman Center, University of Wisconsin Madison, Madison, WI 53705, USA
| | - W Timothy O'Brien
- IDDRC Preclinical Models Core, Children's Hospital of Philadelphia and University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Zhaolan Zhou
- IDDRC Preclinical Models Core, Children's Hospital of Philadelphia and University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA
| | - Ted Abel
- IDDRC Preclinical Models Core, Children's Hospital of Philadelphia and University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, USA; Current affiliation: Iowa Neuroscience Institute, University of Iowa, Iowa City, IA 52242, USA
| | - Li Wang
- IDDRC Neurobehavioral Core, Center for Neuroscience Research, Children's National Health System, Washington, DC 20010, USA
| | - Joshua G Corbin
- IDDRC Neurobehavioral Core, Center for Neuroscience Research, Children's National Health System, Washington, DC 20010, USA
| | - Surabi Veeraragavan
- IDDRC Neurobehavioral Core, Baylor College of Medicine, Houston, TX 77030, USA
| | - Rodney C Samaco
- IDDRC Neurobehavioral Core, Baylor College of Medicine, Houston, TX 77030, USA
| | - Nick A Andrews
- IDDRC Neurodevelopmental Behavior Core, Boston Children's Hospital, Boston, MA 02115, USA
| | - Michela Fagiolini
- IDDRC Neurodevelopmental Behavior Core, Boston Children's Hospital, Boston, MA 02115, USA
| | - Toby B Cole
- IDDRC Rodent Behavior Laboratory, Center on Human Development and Disability, University of Washington, Seattle, WA 98195, USA
| | - Thomas M Burbacher
- IDDRC Rodent Behavior Laboratory, Center on Human Development and Disability, University of Washington, Seattle, WA 98195, USA
| | - Jacqueline N Crawley
- IDDRC Rodent Behavior Core, MIND Institute, University of California Davis School of Medicine, Sacramento, CA 95817, USA.
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16
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Ross JM, Bendahmane M, Fletcher ML. Olfactory Bulb Muscarinic Acetylcholine Type 1 Receptors Are Required for Acquisition of Olfactory Fear Learning. Front Behav Neurosci 2019; 13:164. [PMID: 31379534 PMCID: PMC6659260 DOI: 10.3389/fnbeh.2019.00164] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 07/08/2019] [Indexed: 11/13/2022] Open
Abstract
The olfactory bulb (OB) receives significant cholinergic innervation and widely expresses cholinergic receptors. While acetylcholine (ACh) is essential for olfactory learning, the exact mechanisms by which ACh modulates olfactory learning and whether it is specifically required in the OB remains unknown. Using behavioral pharmacology and optogenetics, we investigated the role of OB ACh in a simple olfactory fear learning paradigm. We find that antagonizing muscarinic ACh receptors (mAChRs) in the OB during fear conditioning but not testing significantly reduces freezing to the conditioned odor, without altering olfactory abilities. Additionally, we demonstrate that m1 mAChRs, rather than m2, are required for acquisition of olfactory fear. Finally, using mice expressing channelrhodopsin in cholinergic neurons, we show that stimulating ACh release specifically in the OB during odor-shock pairing can strengthen olfactory fear learning. Together these results define a role for ACh in olfactory associative learning and OB glomerular plasticity.
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Affiliation(s)
- Jordan M. Ross
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center (UTHSC), Memphis, TN, United States
| | - Mounir Bendahmane
- Department of Pharmacology, University of Michigan, Ann Arbor, MI, United States
| | - Max L. Fletcher
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center (UTHSC), Memphis, TN, United States
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17
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Aversive learning-induced plasticity throughout the adult mammalian olfactory system: insights across development. J Bioenerg Biomembr 2018; 51:15-27. [PMID: 30171506 DOI: 10.1007/s10863-018-9770-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Accepted: 08/27/2018] [Indexed: 10/28/2022]
Abstract
Experiences, such as sensory learning, are known to induce plasticity in mammalian sensory systems. In recent years aversive olfactory learning-induced plasticity has been identified at all stages of the adult olfactory pathway; however, the underlying mechanisms have yet to be identified. Much of the work regarding mechanisms of olfactory associative learning comes from neonates, a time point before which the brain or olfactory system is fully developed. In addition, pups and adults often express different behavioral outcomes when subjected to the same olfactory aversive conditioning paradigm, making it difficult to directly attribute pup mechanisms of plasticity to adults. Despite the differences, there is evidence of similarities between pups and adults in terms of learning-induced changes in the olfactory system, suggesting at least some conserved mechanisms. Identifying these conserved mechanisms of plasticity would dramatically increase our understanding of how the brain is able to alter encoding and consolidation of salient olfactory information even at the earliest stages following aversive learning. The focus of this review is to systematically examine literature regarding olfactory associative learning across developmental stages and search for similarities in order to build testable hypotheses that will inform future studies of aversive learning-induced sensory plasticity in adults.
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18
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Spindle MS, Parsa PV, Bowles SG, D'Souza RD, Vijayaraghavan S. A dominant role for the beta 4 nicotinic receptor subunit in nicotinic modulation of glomerular microcircuits in the mouse olfactory bulb. J Neurophysiol 2018; 120:2036-2048. [PMID: 30089021 DOI: 10.1152/jn.00925.2017] [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] [Indexed: 02/02/2023] Open
Abstract
Nicotinic acetylcholine receptors (nAChRs) regulate information transfer across the main olfactory bulb by instituting a high-pass intensity filter allowing for the filtering out of weak inputs. Excitation-driven inhibition of the glomerular microcircuit via GABA release from periglomerular cells appears to underlie this effect of nAChR activation. The multiplicity of nAChR subtypes and cellular locations raises questions about their respective roles in mediating their effects on the glomerular output. In this study, we address this issue by targeting heteromeric nAChRs using receptor knockouts (KOs) for the two dominant nAChR β-subunit genes known to be expressed in the central nervous system. KOs of the β2-nAChR subunit did not affect nAChR currents from mitral cells (MCs) but attenuated those from the external tufted (ET) cells. In slices from these animals, activation of nAChRs still effectively inhibited excitatory postsynaptic currents (EPSCs) and firing on MCs evoked by the olfactory nerve (ON) stimulation, thereby indicating that the filter mechanism was intact. On the other hand, recordings from β4-KOs showed that nAChR responses from MCs were abolished and those from ET cells were attenuated. Excitation-driven feedback was abolished as was the effect of nAChR activation on ON-evoked EPSCs. Experiments using calcium imaging showed that one possible consequence of the β2-subunit activation might be to alter the time course of calcium transients in juxtaglomerular neurons suggesting a role for these receptors in calcium signaling. Our results indicate that nAChRs containing the β4-subunit are critical in the filtering of odor inputs and play a determinant role in the cholinergic modulation of glomerular output. NEW & NOTEWORTHY In this study, using receptor gene knockouts we examine the relative contributions of heteromeric nAChR subtypes located on different cell types to this effect of receptor activation. Our results demonstrate that nAChRs containing the β4-subunit activate MCs resulting in feedback inhibition from glomerular interneurons. This period of inhibition results in the selective filtering of weak odor inputs providing one mechanism by which nAChRs can enhance discrimination between two closely related odors.
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Affiliation(s)
- Michael S Spindle
- Department of Physiology and Biophysics and the Neuroscience Program, University of Colorado, School of Medicine , Aurora, Colorado
| | - Pirooz V Parsa
- Department of Physiology and Biophysics and the Neuroscience Program, University of Colorado, School of Medicine , Aurora, Colorado
| | - Spencer G Bowles
- Department of Physiology and Biophysics and the Neuroscience Program, University of Colorado, School of Medicine , Aurora, Colorado
| | - Rinaldo D D'Souza
- Department of Physiology and Biophysics and the Neuroscience Program, University of Colorado, School of Medicine , Aurora, Colorado
| | - Sukumar Vijayaraghavan
- Department of Physiology and Biophysics and the Neuroscience Program, University of Colorado, School of Medicine , Aurora, Colorado
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19
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Anhydroecgonine Methyl Ester (AEME), a Product of Cocaine Pyrolysis, Impairs Spatial Working Memory and Induces Striatal Oxidative Stress in Rats. Neurotox Res 2017; 34:834-847. [DOI: 10.1007/s12640-017-9813-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 08/29/2017] [Accepted: 09/03/2017] [Indexed: 12/17/2022]
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