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Tsuboi A. A specific olfactory bulb interneuron subtype Tpbg/5T4 generated at embryonic and neonatal stages. Front Neural Circuits 2024; 18:1427378. [PMID: 38933598 PMCID: PMC11203798 DOI: 10.3389/fncir.2024.1427378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2024] [Accepted: 05/24/2024] [Indexed: 06/28/2024] Open
Abstract
Various mammals have shown that sensory stimulation plays a crucial role in regulating the development of diverse structures, such as the olfactory bulb (OB), cerebral cortex, hippocampus, and retina. In the OB, the dendritic development of excitatory projection neurons like mitral/tufted cells is influenced by olfactory experiences. Odor stimulation is also essential for the dendritic development of inhibitory OB interneurons, such as granule and periglomerular cells, which are continuously produced in the ventricular-subventricular zone throughout life. Based on the morphological and molecular features, OB interneurons are classified into several subtypes. The role for each interneuron subtype in the control of olfactory behavior remains poorly understood due to lack of each specific marker. Among the several OB interneuron subtypes, a specific granule cell subtype, which expresses the oncofetal trophoblast glycoprotein (Tpbg or 5T4) gene, has been reported to be required for odor detection and discrimination behavior. This review will primarily focus on elucidating the contribution of different granule cell subtypes, including the Tpbg/5T4 subtype, to olfactory processing and behavior during the embryonic and adult stages.
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Affiliation(s)
- Akio Tsuboi
- Graduate School of Pharmaceutical Sciences, Osaka University, Toyonaka, Japan
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2
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Chen F, He A, Tang Q, Li S, Liu X, Yin Z, Yao Q, Yu Y, Li A. Cholecystokinin-expressing superficial tufted cells modulate odour representation in the olfactory bulb and olfactory behaviours. J Physiol 2024. [PMID: 38837412 DOI: 10.1113/jp285837] [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: 10/23/2023] [Accepted: 05/15/2024] [Indexed: 06/07/2024] Open
Abstract
In mammals, odour information within the olfactory bulb (OB) is processed by complex neural circuits before being ultimately represented in the action potential activity of mitral/tufted cells (M/Ts). Cholecystokinin-expressing (CCK+) superficial tufted cells (sTCs) are a subset of tufted cells that potentially contribute to olfactory processing in the OB by orchestrating M/T activity. However, the exact role of CCK+ sTCs in modulating odour processing and olfactory function in vivo is largely unknown. Here, we demonstrate that manipulating CCK+ sTCs can generate perception and induce place avoidance. Optogenetic activation/inactivation of CCK+ sTCs exerted strong but differing effects on spontaneous and odour-evoked M/T firing. Furthermore, inactivation of CCK+ sTCs disrupted M/T odour encoding and impaired olfactory detection and odour discrimination. These results establish the role of CCK+ sTCs in odour representation and olfactory behaviours. KEY POINTS: Mice could perceive the activity of CCK+ sTCs and show place avoidance to CCK+ sTC inactivation. Optical activation of CCK+ sTCs increased the percentage of cells with odour response but reduced the odour-evoked response in M/Ts in awake mice. Optical inactivation of CCK+ sTCs greatly decreased spontaneous firing and odour-evoked response in M/Ts. Inactivation of CCK+ sTCs impairs the odour decoding performance of M/Ts and disrupts odour detection and discrimination behaviours in mice. These results indicate that CCK+ sTCs participate in modulating the odour representation and maintaining normal olfactory-related behaviours.
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Affiliation(s)
- Fengjiao Chen
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Ao He
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Qingnan Tang
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Shan Li
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Xingyu Liu
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Zhaoyang Yin
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Quanbei Yao
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Yiqun Yu
- Ear, Nose & Throat Institute, Department of Otolaryngology, Eye, Ear, Nose & Throat Hospital, Fudan University, Shanghai, China
- Clinical and Research Center for Olfactory Disorders, Eye, Ear, Nose & Throat Hospital, Fudan University, Shanghai, China
| | - Anan Li
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
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3
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Goodkey K, Wischmeijer A, Perrin L, Watson AES, Qureshi L, Cordelli DM, Toni F, Gnazzo M, Benedicenti F, Elmaleh-Bergès M, Low KJ, Voronova A. Olfactory bulb anomalies in KBG syndrome mouse model and patients. BMC Med 2024; 22:158. [PMID: 38616269 PMCID: PMC11017579 DOI: 10.1186/s12916-024-03363-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 03/18/2024] [Indexed: 04/16/2024] Open
Abstract
ANKRD11 (ankyrin repeat domain 11) is a chromatin regulator and the only gene associated with KBG syndrome, a rare neurodevelopmental disorder. We have previously shown that Ankrd11 regulates murine embryonic cortical neurogenesis. Here, we show a novel olfactory bulb phenotype in a KBG syndrome mouse model and two diagnosed patients. Conditional knockout of Ankrd11 in murine embryonic neural stem cells leads to aberrant postnatal olfactory bulb development and reduced size due to reduction of the olfactory bulb granule cell layer. We further show that the rostral migratory stream has incomplete migration of neuroblasts, reduced cell proliferation as well as aberrant differentiation of neurons. This leads to reduced neuroblasts and neurons in the olfactory bulb granule cell layer. In vitro, Ankrd11-deficient neural stem cells from the postnatal subventricular zone display reduced migration, proliferation, and neurogenesis. Finally, we describe two clinically and molecularly confirmed KBG syndrome patients with anosmia and olfactory bulb and groove hypo-dysgenesis/agenesis. Our report provides evidence that Ankrd11 is a novel regulator of olfactory bulb development and neuroblast migration. Moreover, our study highlights a novel clinical sign of KBG syndrome linked to ANKRD11 perturbations in mice and humans.
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Affiliation(s)
- Kara Goodkey
- Department of Medical Genetics, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB, T6G 2H7, Canada
- Women and Children's Health Research Institute, University of Alberta, 5-083 Edmonton Clinic Health Academy, Edmonton, AB, T6G 1C9, Canada
| | - Anita Wischmeijer
- Clinical Genetics Service and Coordination Center for Rare Diseases, Department of Pediatrics, Regional Hospital of Bolzano, Bolzano, Italy
| | | | - Adrianne E S Watson
- Department of Medical Genetics, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB, T6G 2H7, Canada
- Women and Children's Health Research Institute, University of Alberta, 5-083 Edmonton Clinic Health Academy, Edmonton, AB, T6G 1C9, Canada
| | - Leenah Qureshi
- Department of Medical Genetics, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB, T6G 2H7, Canada
| | - Duccio Maria Cordelli
- IRCCS Istituto Delle Scienze Neurologiche Di Bologna, UOC Neuropsichiatria Dell'età Pediatrica, Bologna, Italy
| | - Francesco Toni
- IRCCS Istituto Delle Scienze Neurologiche Di Bologna, Programma Di Neuroradiologia Con Tecniche Ad Elevata Complessità (PNTEC), Bologna, Italy
| | - Maria Gnazzo
- Laboratory of Medical Genetics, Translational Cytogenomics Research Unit, Bambino Gesù Children's Hospital, IRCCS, 00165, Rome, Italy
| | - Francesco Benedicenti
- Clinical Genetics Service and Coordination Center for Rare Diseases, Department of Pediatrics, Regional Hospital of Bolzano, Bolzano, Italy
| | | | - Karen J Low
- Department of Academic Child Health, Bristol Medical School, Population Health Sciences, University of Bristol, Bristol, UK
- Clinical Genetics Service, St. Michaels Hospital, Bristol, UK
| | - Anastassia Voronova
- Department of Medical Genetics, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB, T6G 2H7, Canada.
- Women and Children's Health Research Institute, University of Alberta, 5-083 Edmonton Clinic Health Academy, Edmonton, AB, T6G 1C9, Canada.
- Department of Cell Biology, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, AB, T6G 2H7, Canada.
- Faculty of Medicine & Dentistry, Neuroscience and Mental Health Institute, Edmonton, AB, T6G 2E1, Canada.
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Iijima Y, Miki R, Takasugi N, Fujimura M, Uehara T. Characterization of pathological changes in the olfactory system of mice exposed to methylmercury. Arch Toxicol 2024; 98:1163-1175. [PMID: 38367039 PMCID: PMC10944439 DOI: 10.1007/s00204-024-03682-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2023] [Accepted: 01/15/2024] [Indexed: 02/19/2024]
Abstract
Methylmercury (MeHg) is a well-known environmental neurotoxicant that causes severe brain disorders such as Minamata disease. Although some patients with Minamata disease develop olfactory dysfunction, the underlying pathomechanism is largely unknown. We examined the effects of MeHg on the olfactory system using a model of MeHg poisoning in which mice were administered 30 ppm MeHg in drinking water for 8 weeks. Mice exposed to MeHg displayed significant mercury accumulation in the olfactory pathway, including the nasal mucosa, olfactory bulb, and olfactory cortex. The olfactory epithelium was partially atrophied, and olfactory sensory neurons were diminished. The olfactory bulb exhibited an increase in apoptotic cells, hypertrophic astrocytes, and amoeboid microglia, mainly in the granular cell layer. Neuronal cell death was observed in the olfactory cortex, particularly in the ventral tenia tecta. Neuronal cell death was also remarkable in higher-order areas such as the orbitofrontal cortex. Correlation analysis showed that neuronal loss in the olfactory cortex was strongly correlated with the plasma mercury concentration. Our results indicate that MeHg is an olfactory toxicant that damages the central regions involved in odor perception. The model described herein is useful for analyzing the mechanisms and treatments of olfactory dysfunction in MeHg-intoxicated patients.
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Affiliation(s)
- Yuta Iijima
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, 700‑8530, Japan
| | - Ryohei Miki
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, 700‑8530, Japan
| | - Nobumasa Takasugi
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, 700‑8530, Japan
| | - Masatake Fujimura
- Department of Basic Medical Science, National Institute for Minamata Disease, Kumamoto, 867‑0008, Japan
| | - Takashi Uehara
- Department of Medicinal Pharmacology, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, 700‑8530, Japan.
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5
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Bao S, Romero JM, Belfort BD, Arenkiel BR. Signaling mechanisms underlying activity-dependent integration of adult-born neurons in the mouse olfactory bulb. Genesis 2024; 62:e23595. [PMID: 38553878 PMCID: PMC10987073 DOI: 10.1002/dvg.23595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 03/18/2024] [Accepted: 03/19/2024] [Indexed: 04/02/2024]
Abstract
Adult neurogenesis has fascinated the field of neuroscience for decades given the prospects of harnessing mechanisms that facilitate the rewiring and/or replacement of adult brain tissue. The subgranular zone of the hippocampus and the subventricular zone of the lateral ventricle are the two main areas in the brain that exhibit ongoing neurogenesis. Of these, adult-born neurons within the olfactory bulb have proven to be a powerful model for studying circuit plasticity, providing a broad and accessible avenue into neuron development, migration, and continued circuit integration within adult brain tissue. This review focuses on some of the recognized molecular and signaling mechanisms underlying activity-dependent adult-born neuron development. Notably, olfactory activity and behavioral states contribute to adult-born neuron plasticity through sensory and centrifugal inputs, in which calcium-dependent transcriptional programs, local translation, and neuropeptide signaling play important roles. This review also highlights areas of needed continued investigation to better understand the remarkable phenomenon of adult-born neuron integration.
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Affiliation(s)
- Suyang Bao
- Development, Disease Models, and Therapeutics Graduate Program, Baylor College of Medicine, Houston, Texas 77030, USA
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas 77030, USA
| | - Juan M. Romero
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas 77030, USA
- Medical Scientist Training Program, Baylor College of Medicine, Houston, Texas 77030, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Benjamin D.W. Belfort
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas 77030, USA
- Medical Scientist Training Program, Baylor College of Medicine, Houston, Texas 77030, USA
- Genetics and Genomics Graduate Program, Baylor College of Medicine, Houston, Texas 77030, USA
| | - Benjamin R. Arenkiel
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030, USA
- Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas 77030, USA
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030, USA
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6
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Hotha A, Ganesh CB. GABA-immunoreactive neurons in the Central Nervous System of the viviparous teleost Poecilia sphenops. J Chem Neuroanat 2023; 133:102339. [PMID: 37689218 DOI: 10.1016/j.jchemneu.2023.102339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 09/06/2023] [Accepted: 09/06/2023] [Indexed: 09/11/2023]
Abstract
Gamma-aminobutyric acid (GABA) functions as the primary inhibitory neurotransmitter within the central nervous system (CNS) of vertebrates. In this study, we examined the distribution pattern of GABA-immunoreactive (GABA-ir) cells and fibres in the CNS of the viviparous teleost Poecilia sphenops using immunofluorescence method. GABA immunoreactivity was seen in the glomerular, mitral, and granular layers of the olfactory bulbs, as well as in most parts of the dorsal and ventral telencephalon. The preoptic area consisted of a small cluster of GABA-ir cells, whereas extensively labelled GABA-ir neurons were observed in the hypothalamic areas, including the paraventricular organ, tuberal hypothalamus, nucleus recessus lateralis, nucleus recessus posterioris, and inferior lobes. In the thalamus, GABA-positive neurons were only found in the ventral thalamic and central posterior thalamic nuclei, whereas the dorsal part of the nucleus pretectalis periventricularis consisted of a few GABA-ir cells. GABA-immunoreactivity was extensively seen in the alar and basal subdivisions of the midbrain, whereas in the rhombencephalon, GABA-ir cells and fibres were found in the cerebellum, motor nucleus of glossopharyngeal and vagal nerves, nucleus commissuralis of Cajal, and reticular formation. In the spinal cord, GABA-ir cells and fibres were observed in the dorsal horn, ventral horn, and around the central canal. Overall, the extensive distribution of GABA-ir cells and fibres throughout the CNS suggests several roles for GABA, including the neuroendocrine, viscerosensory, and somatosensory functions, for the first time in a viviparous teleost.
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Affiliation(s)
- Achyutham Hotha
- Neuroendocrinology Research Laboratory, Department of Studies in Zoology, Karnatak University, Dharwad 580 003, India
| | - C B Ganesh
- Neuroendocrinology Research Laboratory, Department of Studies in Zoology, Karnatak University, Dharwad 580 003, India.
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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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Gomes FDC, Santos IBF, Stephani CM, Ferrari MDFR, Galvis-Alonso OY, Goloni-Bertollo EM, Melo-Neto JSD, Pavarino ÉC. Vitamin D3 supplementation may attenuate morphological and molecular abnormalities of the olfactory bulb in a mouse model of Down syndrome. Tissue Cell 2022; 78:101898. [DOI: 10.1016/j.tice.2022.101898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Revised: 08/12/2022] [Accepted: 08/13/2022] [Indexed: 11/28/2022]
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Schubert C, Schulz K, Träger S, Plath AL, Omriouate A, Rosenkranz SC, Morellini F, Friese MA, Hirnet D. Neuronal Adenosine A1 Receptor is Critical for Olfactory Function but Unable to Attenuate Olfactory Dysfunction in Neuroinflammation. Front Cell Neurosci 2022; 16:912030. [PMID: 35846561 PMCID: PMC9279574 DOI: 10.3389/fncel.2022.912030] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2022] [Accepted: 06/08/2022] [Indexed: 11/13/2022] Open
Abstract
Adenine nucleotides, such as adenosine triphosphate (ATP), adenosine diphosphate (ADP), as well as the nucleoside adenosine are important modulators of neuronal function by engaging P1 and P2 purinergic receptors. In mitral cells, signaling of the G protein-coupled P1 receptor adenosine 1 receptor (A1R) affects the olfactory sensory pathway by regulating high voltage-activated calcium channels and two-pore domain potassium (K2P) channels. The inflammation of the central nervous system (CNS) impairs the olfactory function and gives rise to large amounts of extracellular ATP and adenosine, which act as pro-inflammatory and anti-inflammatory mediators, respectively. However, it is unclear whether neuronal A1R in the olfactory bulb modulates the sensory function and how this is impacted by inflammation. Here, we show that signaling via neuronal A1R is important for the physiological olfactory function, while it cannot counteract inflammation-induced hyperexcitability and olfactory deficit. Using neuron-specific A1R-deficient mice in patch-clamp recordings, we found that adenosine modulates spontaneous dendro-dendritic signaling in mitral and granule cells via A1R. Furthermore, neuronal A1R deficiency resulted in olfactory dysfunction in two separate olfactory tests. In mice with experimental autoimmune encephalomyelitis (EAE), we detected immune cell infiltration and microglia activation in the olfactory bulb as well as hyperexcitability of mitral cells and olfactory dysfunction. However, neuron-specific A1R activity was unable to attenuate glutamate excitotoxicity in the primary olfactory bulb neurons in vitro or EAE-induced olfactory dysfunction and disease severity in vivo. Together, we demonstrate that A1R modulates the dendro-dendritic inhibition (DDI) at the site of mitral and granule cells and impacts the processing of the olfactory sensory information, while A1R activity was unable to counteract inflammation-induced hyperexcitability.
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Affiliation(s)
- Charlotte Schubert
- Institute of Neuroimmunology and Multiple Sclerosis (INIMS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Kristina Schulz
- Division of Neurophysiology, Institute of Cell and Systems Biology of Animals, University of Hamburg, Hamburg, Germany
| | - Simone Träger
- Institute of Neuroimmunology and Multiple Sclerosis (INIMS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Anna-Lena Plath
- Research Group Behavioral Biology, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Asina Omriouate
- Research Group Behavioral Biology, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sina C. Rosenkranz
- Institute of Neuroimmunology and Multiple Sclerosis (INIMS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Fabio Morellini
- Research Group Behavioral Biology, Center for Molecular Neurobiology (ZMNH), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Manuel A. Friese
- Institute of Neuroimmunology and Multiple Sclerosis (INIMS), University Medical Center Hamburg-Eppendorf, Hamburg, Germany
- *Correspondence: Manuel A. Friese,
| | - Daniela Hirnet
- Division of Neurophysiology, Institute of Cell and Systems Biology of Animals, University of Hamburg, Hamburg, Germany
- Daniela Hirnet,
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Upstream γ-synchronization enhances odor processing in downstream neurons. Cell Rep 2022; 39:110693. [PMID: 35443179 DOI: 10.1016/j.celrep.2022.110693] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2021] [Revised: 02/10/2022] [Accepted: 03/25/2022] [Indexed: 11/22/2022] Open
Abstract
γ-oscillatory activity is ubiquitous across brain areas. Numerous studies have suggested that γ-synchrony is likely to enhance the transmission of sensory information. However, direct causal evidence is still lacking. Here, we test this hypothesis in the mouse olfactory system, where local GABAergic granule cells (GCs) in the olfactory bulb shape mitral/tufted cell (MTC) excitatory output from the olfactory bulb. By optogenetically modulating GC activity, we successfully dissociate MTC γ-synchronization from its firing rates. Recording of odor responses in downstream piriform cortex neurons shows that increasing MTC γ-synchronization enhances cortical neuron odor-evoked firing rates, reduces response variability, and improves odor ensemble representation. These gains occur despite a reduction in MTC firing rates. Furthermore, reducing MTC γ-synchronization without changing the MTC firing rates, by suppressing GC activity, degrades piriform cortex odor-evoked responses. These findings provide causal evidence that increased γ-synchronization enhances the transmission of sensory information between two brain regions.
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Wang D, Wu J, Liu P, Li X, Li J, He M, Li A. VIP interneurons regulate olfactory bulb output and contribute to odor detection and discrimination. Cell Rep 2022; 38:110383. [PMID: 35172159 DOI: 10.1016/j.celrep.2022.110383] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 11/09/2021] [Accepted: 01/24/2022] [Indexed: 11/03/2022] Open
Abstract
In the olfactory bulb (OB), olfactory information represented by mitral/tufted cells (M/Ts) is extensively modulated by local inhibitory interneurons before being transmitted to the olfactory cortex. While the crucial roles of cortical vasoactive-intestinal-peptide-expressing (VIP) interneurons have been extensively studied, their precise function in the OB remains elusive. Here, we identify the synaptic connectivity of VIP interneurons onto mitral cells (MCs) and demonstrate their important role in olfactory behaviors. Optogenetic activation of VIP interneurons reduced both spontaneous and odor-evoked activity of M/Ts in awake mice. Whole-cell recordings revealed that VIP interneurons decrease MC firing through direct inhibitory synaptic connections with MCs. Furthermore, inactivation of VIP interneurons leads to increased MC firing and impaired olfactory detection and odor discrimination. Therefore, our results demonstrate that VIP interneurons control OB output and play critical roles in odor processing and olfactory behaviors.
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Affiliation(s)
- Dejuan Wang
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou 221004, China
| | - Jing Wu
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou 221004, China
| | - Penglai Liu
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou 221004, China
| | - Xiaowen Li
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou 221004, China
| | - Jiaxin Li
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou 221004, China
| | - Miao He
- Department of Neurology, State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Zhongshan Hospital, Fudan University, Shanghai 200032, China
| | - Anan Li
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou 221004, China.
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12
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Kersen DEC, Tavoni G, Balasubramanian V. Connectivity and dynamics in the olfactory bulb. PLoS Comput Biol 2022; 18:e1009856. [PMID: 35130267 PMCID: PMC8853646 DOI: 10.1371/journal.pcbi.1009856] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Revised: 02/17/2022] [Accepted: 01/22/2022] [Indexed: 12/22/2022] Open
Abstract
Dendrodendritic interactions between excitatory mitral cells and inhibitory granule cells in the olfactory bulb create a dense interaction network, reorganizing sensory representations of odors and, consequently, perception. Large-scale computational models are needed for revealing how the collective behavior of this network emerges from its global architecture. We propose an approach where we summarize anatomical information through dendritic geometry and density distributions which we use to calculate the connection probability between mitral and granule cells, while capturing activity patterns of each cell type in the neural dynamical systems theory of Izhikevich. In this way, we generate an efficient, anatomically and physiologically realistic large-scale model of the olfactory bulb network. Our model reproduces known connectivity between sister vs. non-sister mitral cells; measured patterns of lateral inhibition; and theta, beta, and gamma oscillations. The model in turn predicts testable relationships between network structure and several functional properties, including lateral inhibition, odor pattern decorrelation, and LFP oscillation frequency. We use the model to explore the influence of cortex on the olfactory bulb, demonstrating possible mechanisms by which cortical feedback to mitral cells or granule cells can influence bulbar activity, as well as how neurogenesis can improve bulbar decorrelation without requiring cell death. Our methodology provides a tractable tool for other researchers.
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Affiliation(s)
- 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
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - 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
| | - Vijay Balasubramanian
- Computational Neuroscience Initiative, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- Department of Bioengineering, 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, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
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13
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Ziegler-Waldkirch S, Friesen M, Loreth D, Sauer JF, Kemna S, Hilse A, Erny D, Helm C, d´Errico P, Prinz M, Bartos M, Meyer-Luehmann M. Seed-induced Aβ deposition alters neuronal function and impairs olfaction in a mouse model of Alzheimer's disease. Mol Psychiatry 2022; 27:4274-4284. [PMID: 35869271 PMCID: PMC9718674 DOI: 10.1038/s41380-022-01686-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 06/22/2022] [Accepted: 06/27/2022] [Indexed: 02/07/2023]
Abstract
Alzheimer's disease (AD) is characterized by the accumulation of amyloid-β (Aβ) which ultimately forms plaques. These Aβ deposits can be induced in APP transgenic mouse models by prion-like seeding. It has been widely accepted that anosmia and hyposmia occur during the early stages of AD, even before cognitive deficits are present. In order to determine the impact of seed-induced Aβ deposits on olfaction, we performed intracerebral injections of seed-competent brain homogenate into the olfactory bulb of young pre-depositing APP transgenic mice. Remarkably, we observed a dramatic olfactory impairment in those mice. Furthermore, the number of newborn neurons as well as the activity of cells in the mitral cell layer was decreased. Notably, exposure to an enriched environment reduced Aβ seeding, vivified neurogenesis and most importantly reversed olfactory deficits. Based on our findings, we conclude that altered neuronal function as a result of induced Aβ pathology might contribute to olfactory dysfunction in AD.
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Affiliation(s)
- Stephanie Ziegler-Waldkirch
- grid.7708.80000 0000 9428 7911Department of Neurology, Medical Center – University of Freiburg, 79106 Freiburg, Germany ,grid.5963.9Faculty of Medicine, University of Freiburg, 79110 Freiburg, Germany
| | - Marina Friesen
- grid.7708.80000 0000 9428 7911Department of Neurology, Medical Center – University of Freiburg, 79106 Freiburg, Germany ,grid.5963.9Faculty of Medicine, University of Freiburg, 79110 Freiburg, Germany ,grid.5963.9Faculty of Biology, University of Freiburg, 79110 Freiburg, Germany
| | - Desirée Loreth
- grid.7708.80000 0000 9428 7911Department of Neurology, Medical Center – University of Freiburg, 79106 Freiburg, Germany ,grid.5963.9Faculty of Medicine, University of Freiburg, 79110 Freiburg, Germany ,grid.13648.380000 0001 2180 3484Institute of Cellular and Integrative Physiology, University Medical Center Hamburg-Eppendorf, 20246 Hamburg, Germany
| | - Jonas-Frederic Sauer
- grid.5963.9Faculty of Medicine, University of Freiburg, 79110 Freiburg, Germany ,grid.5963.9Institute for Physiology I, Systemic and Cellular Neurophysiology, University of Freiburg, 79104 Freiburg, Germany
| | - Solveig Kemna
- grid.7708.80000 0000 9428 7911Department of Neurology, Medical Center – University of Freiburg, 79106 Freiburg, Germany ,grid.5963.9Faculty of Medicine, University of Freiburg, 79110 Freiburg, Germany
| | - Alexandra Hilse
- grid.7708.80000 0000 9428 7911Department of Neurology, Medical Center – University of Freiburg, 79106 Freiburg, Germany ,grid.5963.9Faculty of Medicine, University of Freiburg, 79110 Freiburg, Germany ,grid.5963.9Faculty of Biology, University of Freiburg, 79110 Freiburg, Germany
| | - Daniel Erny
- grid.5963.9Faculty of Medicine, University of Freiburg, 79110 Freiburg, Germany ,grid.5963.9Institute of Neuropathology, University of Freiburg, 79106 Freiburg, Germany ,grid.5963.9Berta-Ottenstein-Programme, Faculty of Medicine, University of Freiburg, 79110 Freiburg, Germany
| | - Christina Helm
- grid.7708.80000 0000 9428 7911Department of Neurology, Medical Center – University of Freiburg, 79106 Freiburg, Germany ,grid.5963.9Faculty of Medicine, University of Freiburg, 79110 Freiburg, Germany
| | - Paolo d´Errico
- grid.7708.80000 0000 9428 7911Department of Neurology, Medical Center – University of Freiburg, 79106 Freiburg, Germany ,grid.5963.9Faculty of Medicine, University of Freiburg, 79110 Freiburg, Germany
| | - Marco Prinz
- grid.5963.9Faculty of Medicine, University of Freiburg, 79110 Freiburg, Germany ,grid.5963.9Institute of Neuropathology, University of Freiburg, 79106 Freiburg, Germany ,grid.5963.9Center for Basics in NeuroModulation (NeuroModulBasics), Faculty of Medicine University of Freiburg, 79110 Freiburg, Germany ,grid.5963.9Signalling Research Centres BIOSS and CIBSS, University of Freiburg, 79104 Freiburg, Germany
| | - Marlene Bartos
- grid.5963.9Faculty of Medicine, University of Freiburg, 79110 Freiburg, Germany ,grid.5963.9Institute for Physiology I, Systemic and Cellular Neurophysiology, University of Freiburg, 79104 Freiburg, Germany ,grid.5963.9Center for Basics in NeuroModulation (NeuroModulBasics), Faculty of Medicine University of Freiburg, 79110 Freiburg, Germany
| | - Melanie Meyer-Luehmann
- Department of Neurology, Medical Center - University of Freiburg, 79106, Freiburg, Germany. .,Faculty of Medicine, University of Freiburg, 79110, Freiburg, Germany. .,Center for Basics in NeuroModulation (NeuroModulBasics), Faculty of Medicine University of Freiburg, 79110, Freiburg, Germany.
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14
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Khani E, Khiali S, Beheshtirouy S, Entezari-Maleki T. Potential pharmacologic treatments for COVID-19 smell and taste loss: A comprehensive review. Eur J Pharmacol 2021; 912:174582. [PMID: 34678243 PMCID: PMC8524700 DOI: 10.1016/j.ejphar.2021.174582] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 10/08/2021] [Accepted: 10/18/2021] [Indexed: 12/30/2022]
Abstract
The acute loss of taste and smell following COVID-19 are hallmark symptoms that affect 20-85% of patients. However, the pathophysiology and potential treatments of COVID-19 smell and taste loss are not fully understood. We searched the literature to review the potential pathologic pathways and treatment options for COVID-19 smell and taste loss. The interaction of novel coronavirus with ACE-2 receptors expressed on sustentacular cells and taste buds results in direct damage to the olfactory and gustatory systems. Also, the invasion of the virus to the olfactory neurons and consequent local inflammation are other proposed mechanisms. Therefore, COVID-19 patients with smell or taste loss may benefit from neuroprotective, anti-inflammatory, or depolarizing agents. Based on the current evidence, phosphodiesterase inhibitors, insulin, and corticosteroids can be promising for the management of COVID-19 smell and taste loss. This review provided crucial information for treating COVID-19-related smell and/or taste loss, urging to perform large clinical trials to find optimum treatment options.
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Affiliation(s)
- Elnaz Khani
- Department of Clinical Pharmacy, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Sajad Khiali
- Department of Clinical Pharmacy, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Samineh Beheshtirouy
- Department of Clinical Pharmacy, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Taher Entezari-Maleki
- Department of Clinical Pharmacy, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran,Cardiovascular Research Center, Tabriz University of Medical Sciences, Tabriz, Iran,Corresponding author. Department of Clinical Pharmacy, Faculty of Pharmacy, Tabriz University of Medical Sciences, Tabriz, P.O. Box: 51664-14766 12, Iran
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15
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Yan Y, Aierken A, Wang C, Song D, Ni J, Wang Z, Quan Z, Qing H. A potential biomarker of preclinical Alzheimer's disease: The olfactory dysfunction and its pathogenesis-based neural circuitry impairments. Neurosci Biobehav Rev 2021; 132:857-869. [PMID: 34810025 DOI: 10.1016/j.neubiorev.2021.11.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Revised: 10/26/2021] [Accepted: 11/07/2021] [Indexed: 01/24/2023]
Abstract
The olfactory dysfunction can signal and act as a potential biomarker of preclinical AD. However, the precise regulatory mechanism of olfactory function on the neural pathogenesis of AD is still unclear. The impairment of neural networks in olfaction system has been shown to be tightly associated with AD. As key brain regions of the olfactory system, the olfactory bulb (OB) and the piriform cortex (PCx) have a profound influence on the olfactory function. Therefore, this review will explore the mechanism of olfactory dysfunction in preclinical AD in the perspective of abnormal neural networks in the OB and PCx and their associated brain regions, especially from two aspects of aberrant oscillations and synaptic plasticity damages, which help better understand the underlying mechanism of olfactory neural network damages related to AD.
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Affiliation(s)
- Yan Yan
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Ailikemu Aierken
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Chunjian Wang
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Da Song
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Junjun Ni
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China
| | - Zhe Wang
- Advanced Innovation Center for Human Brain Protection, Capital Medical University, The National Clinical Research Center for Geriatric Disease, Xuanwu Hospital, Capital Medical University, Beijing, China
| | - Zhenzhen Quan
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.
| | - Hong Qing
- Key Laboratory of Molecular Medicine and Biotherapy, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.
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16
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Hu B, Geng C, Guo F, Liu Y, Zong YC, Hou XY. GABA A receptor agonist muscimol rescues inhibitory microcircuit defects in the olfactory bulb and improves olfactory function in APP/PS1 transgenic mice. Neurobiol Aging 2021; 108:47-57. [PMID: 34507271 DOI: 10.1016/j.neurobiolaging.2021.08.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 05/28/2021] [Accepted: 08/02/2021] [Indexed: 02/09/2023]
Abstract
Olfactory damage develops at the early stages of Alzheimer's disease (AD). While amyloid-β (Aβ) oligomers are shown to impair inhibitory circuits in the olfactory bulb (OB), its underlying mechanisms remain unclear. Here, we investigated the olfactory dysfunction due to impaired inhibitory transmission to mitral cells (MCs) of the OB in APP/PS1 mice. Using electrophysiological studies, we found that MCs exhibited increased spontaneous firing rates as early as 3 months, much before development of Aβ deposits in the brain. Furthermore, the frequencies but not amplitudes of MC inhibitory postsynaptic currents decreased markedly, suggesting that presynaptic GABA release is impaired while postsynaptic GABAA receptor responses remain intact. Notably, muscimol, a GABAA receptor agonist, improved odor identification and discrimination behaviors in APP/PS1 mice, reduced MC basal firing activity, and rescued inhibitory circuits along with reducing the Aβ burden in the OB. Our study links the presynaptic deficits of GABAergic transmission to olfactory dysfunction and subsequent AD development and implicates the therapeutic potential of maintaining local inhibitory microcircuits against early AD progression.
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Affiliation(s)
- Bin Hu
- Research Center for Biochemistry and Molecular Biology, Jiangsu Key Laboratory of Brain Disease Bioinformation, Xuzhou Medical University, Xuzhou, China
| | - Chi Geng
- Research Center for Biochemistry and Molecular Biology, Jiangsu Key Laboratory of Brain Disease Bioinformation, Xuzhou Medical University, Xuzhou, China
| | - Feng Guo
- Research Center for Biochemistry and Molecular Biology, Jiangsu Key Laboratory of Brain Disease Bioinformation, Xuzhou Medical University, Xuzhou, China
| | - Ying Liu
- Research Center for Biochemistry and Molecular Biology, Jiangsu Key Laboratory of Brain Disease Bioinformation, Xuzhou Medical University, Xuzhou, China; State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing, China
| | - Yu-Chen Zong
- Research Center for Biochemistry and Molecular Biology, Jiangsu Key Laboratory of Brain Disease Bioinformation, Xuzhou Medical University, Xuzhou, China
| | - Xiao-Yu Hou
- Research Center for Biochemistry and Molecular Biology, Jiangsu Key Laboratory of Brain Disease Bioinformation, Xuzhou Medical University, Xuzhou, China; State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Nanjing, China.
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17
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Zhu J, Sun S, Zhou X. SPARK-X: non-parametric modeling enables scalable and robust detection of spatial expression patterns for large spatial transcriptomic studies. Genome Biol 2021; 22:184. [PMID: 34154649 PMCID: PMC8218388 DOI: 10.1186/s13059-021-02404-0] [Citation(s) in RCA: 69] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 06/07/2021] [Indexed: 01/01/2023] Open
Abstract
Spatial transcriptomic studies are becoming increasingly common and large, posing important statistical and computational challenges for many analytic tasks. Here, we present SPARK-X, a non-parametric method for rapid and effective detection of spatially expressed genes in large spatial transcriptomic studies. SPARK-X not only produces effective type I error control and high power but also brings orders of magnitude computational savings. We apply SPARK-X to analyze three large datasets, one of which is only analyzable by SPARK-X. In these data, SPARK-X identifies many spatially expressed genes including those that are spatially expressed within the same cell type, revealing new biological insights.
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Affiliation(s)
- Jiaqiang Zhu
- Department of Biostatistics, University of Michigan, Ann Arbor, MI, 48109, USA
- Center for Statistical Genetics, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Shiquan Sun
- Department of Biostatistics, University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Epidemiology and Biostatistics, Xi'an Jiaotong University, Xi'an, Shaanxi, 710061, P.R. China
| | - Xiang Zhou
- Department of Biostatistics, University of Michigan, Ann Arbor, MI, 48109, USA.
- Center for Statistical Genetics, University of Michigan, Ann Arbor, MI, 48109, USA.
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18
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Mitrano DA, Houle SE, Pearce P, Quintanilla RM, Lockhart BK, Genovese BC, Schendzielos RA, Croushore EE, Dymond EM, Bogenpohl JW, Grau HJ, Webb LS. Olfactory dysfunction in the 3xTg-AD model of Alzheimer's disease. IBRO Neurosci Rep 2021; 10:51-61. [PMID: 33842910 PMCID: PMC8019944 DOI: 10.1016/j.ibneur.2020.12.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 12/13/2020] [Indexed: 12/01/2022] Open
Abstract
Alzheimer's disease (AD) is an incurable neurodegenerative disease in which the risk of development increases with age. People with AD are plagued with deficits in their cognition, memory, and basic social skills. Many of these deficits are believed to be caused by the formation of amyloid-β plaques and neurofibrillary tangles in regions of the brain associated with memory, such as the hippocampus. However, one of the early, preclinical symptoms of AD is the loss of olfactory detection and discrimination. To determine if a mouse model of AD expresses the same olfactory dysfunction seen in human AD, 3xTg-AD mice were given a buried food test and, unlike previous studies, compared to their background and parental strains. Results showed that over 52 weeks, the 3xTg-AD mice took significantly longer to find the buried food than the control strains. The olfactory bulbs of the 3xTg-AD mice were removed, sliced, and stained using Congo red for histological analysis. Amyloid deposits were observed predominantly in the granule layer of the olfactory bulb beginning at 13 weeks of age in 3xTg-AD mice, but not in the control strains of mice. Further examination of the buried food test data revealed that 3xTg-AD females had a significantly longer latency to detect the buried food than males beginning at 26 weeks of age. Overall, this study provides further validation of the 3xTg-AD mouse model of AD and supports the idea that simple olfactory testing could be part of the diagnostic process for human AD.
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Affiliation(s)
- Darlene A. Mitrano
- Department of Molecular Biology & Chemistry, Christopher Newport University, 1 Avenue of the Arts, Newport News, VA 23606, USA
- Program in Neuroscience, Christopher Newport University, 1 Avenue of the Arts, Newport News, VA 23606, USA
| | - Sam E. Houle
- Program in Neuroscience, Christopher Newport University, 1 Avenue of the Arts, Newport News, VA 23606, USA
| | - Patrick Pearce
- Program in Neuroscience, Christopher Newport University, 1 Avenue of the Arts, Newport News, VA 23606, USA
| | - Ricardo M. Quintanilla
- Department of Molecular Biology & Chemistry, Christopher Newport University, 1 Avenue of the Arts, Newport News, VA 23606, USA
| | - Blakely K. Lockhart
- Program in Neuroscience, Christopher Newport University, 1 Avenue of the Arts, Newport News, VA 23606, USA
| | - Benjamin C. Genovese
- Department of Molecular Biology & Chemistry, Christopher Newport University, 1 Avenue of the Arts, Newport News, VA 23606, USA
| | - Rachel A. Schendzielos
- Department of Molecular Biology & Chemistry, Christopher Newport University, 1 Avenue of the Arts, Newport News, VA 23606, USA
| | - Emma E. Croushore
- Department of Molecular Biology & Chemistry, Christopher Newport University, 1 Avenue of the Arts, Newport News, VA 23606, USA
| | - Ethan M. Dymond
- Department of Molecular Biology & Chemistry, Christopher Newport University, 1 Avenue of the Arts, Newport News, VA 23606, USA
| | - James W. Bogenpohl
- Department of Molecular Biology & Chemistry, Christopher Newport University, 1 Avenue of the Arts, Newport News, VA 23606, USA
- Program in Neuroscience, Christopher Newport University, 1 Avenue of the Arts, Newport News, VA 23606, USA
| | - Harold J. Grau
- Department of Molecular Biology & Chemistry, Christopher Newport University, 1 Avenue of the Arts, Newport News, VA 23606, USA
- Program in Neuroscience, Christopher Newport University, 1 Avenue of the Arts, Newport News, VA 23606, USA
| | - Lisa Smith Webb
- Department of Molecular Biology & Chemistry, Christopher Newport University, 1 Avenue of the Arts, Newport News, VA 23606, USA
- Program in Neuroscience, Christopher Newport University, 1 Avenue of the Arts, Newport News, VA 23606, USA
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19
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Touj S, Cloutier S, Jemâa A, Piché M, Bronchti G, Al Aïn S. Better Olfactory Performance and Larger Olfactory Bulbs in a Mouse Model of Congenital Blindness. Chem Senses 2021; 45:523-531. [PMID: 32766717 DOI: 10.1093/chemse/bjaa052] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
It is well established that early blindness results in enhancement of the remaining nonvisual sensory modalities accompanied by functional and anatomical brain plasticity. While auditory and tactile functions have been largely investigated, the results regarding olfactory functions remained less explored and less consistent. In the present study, we investigated olfactory function in blind mice using 3 tests: the buried food test, the olfactory threshold test, and the olfactory performance test. The results indicated better performance of blind mice in the buried food test and odor performance test while there was no difference in the olfactory threshold test. Using histological measurements, we also investigated if there was anatomical plasticity in the olfactory bulbs (OB), the most salient site for olfactory processing. The results indicated a larger volume of the OB driven by larger glomerular and granular layers in blind mice compared with sighted mice. Structural plasticity in the OB may underlie the enhanced olfactory performance in blind mice.
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Affiliation(s)
- Sara Touj
- Department of Anatomy, Université du Québec à Trois-Rivières, Boul. des Forges, Trois-Rivières, Canada
| | - Samie Cloutier
- Department of Anatomy, Université du Québec à Trois-Rivières, Boul. des Forges, Trois-Rivières, Canada
| | - Amel Jemâa
- Department of Anatomy, Université du Québec à Trois-Rivières, Boul. des Forges, Trois-Rivières, Canada
| | - Mathieu Piché
- Department of Anatomy, Université du Québec à Trois-Rivières, Boul. des Forges, Trois-Rivières, Canada
| | - Gilles Bronchti
- Department of Anatomy, Université du Québec à Trois-Rivières, Boul. des Forges, Trois-Rivières, Canada
| | - Syrina Al Aïn
- Department of Anatomy, Université du Québec à Trois-Rivières, Boul. des Forges, Trois-Rivières, Canada
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20
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Kullander K, Topolnik L. Cortical disinhibitory circuits: cell types, connectivity and function. Trends Neurosci 2021; 44:643-657. [PMID: 34006387 DOI: 10.1016/j.tins.2021.04.009] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 04/16/2021] [Accepted: 04/22/2021] [Indexed: 12/16/2022]
Abstract
The concept of a dynamic excitation/inhibition balance tuned by circuit disinhibition, which can shape information flow during complex behavioral tasks, has arisen as an important and conserved information-processing motif. In cortical circuits, different subtypes of GABAergic inhibitory interneurons are connected to each other, offering an anatomical foundation for disinhibitory processes. Moreover, a subpopulation of GABAergic cells that express vasoactive intestinal polypeptide (VIP) preferentially innervates inhibitory interneurons, highlighting their central role in disinhibitory modulation. We discuss inhibitory neuron subtypes involved in disinhibition, with a focus on local circuits and long-range synaptic connections that drive disinhibitory function. We highlight multiple layers of disinhibition across cortical circuits that regulate behavior and serve to maintain an excitation/inhibition balance.
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Affiliation(s)
- Klas Kullander
- Department of Neuroscience, Uppsala University, Uppsala, Sweden.
| | - Lisa Topolnik
- Department of Biochemistry, Microbiology, and Bioinformatics, Laval University, Québec, QC, Canada; Neuroscience Axis, Centre de Recherche du Centre Hospitalier Universitaire de Québec (CRCHUQ), Laval University, Québec, QC, Canada.
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21
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Egger V, Kuner T. Olfactory bulb granule cells: specialized to link coactive glomerular columns for percept generation and discrimination of odors. Cell Tissue Res 2021; 383:495-506. [PMID: 33404844 PMCID: PMC7873091 DOI: 10.1007/s00441-020-03402-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 12/14/2020] [Indexed: 12/16/2022]
Abstract
The role of granule cells in olfactory processing is surrounded by several enigmatic observations, such as the purpose of reciprocal spines and the mechanisms for GABA release, the apparently low firing activity and recurrent inhibitory drive of granule cells, the missing proof for functional reciprocal connectivity, and the apparently negligible contribution to lateral inhibition. Here, we summarize recent results with regard to both the mechanisms of GABA release and the behavioral relevance of granule cell activity during odor discrimination. We outline a novel hypothesis that has the potential to resolve most of these enigmas and allows further predictions on the function of granule cells in odor processing. Briefly, recent findings imply that GABA release from the reciprocal spine requires a local spine action potential and the cooperative action of NMDA receptors and high voltage-activated Ca2+ channels. Thus, lateral inhibition is conditional on activity in the principal neurons connected to a granule cell and tightly intertwined with recurrent inhibition. This notion allows us to infer that lateral inhibition between principal neurons occurs "on demand," i.e., selectively on coactive mitral and tufted cells, and thus can provide directed, dynamically switched lateral inhibition in a sensory system with 1000 input channels organized in glomerular columns. The mechanistic underpinnings of this hypothesis concur with findings from odor discrimination behavior in mice with synaptic proteins deleted in granule cells. In summary, our hypothesis explains the unusual microcircuit of the granule cell reciprocal spine as a means of olfactory combinatorial coding.
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Affiliation(s)
- Veronica Egger
- Institute of Zoology, Regensburg University, Universitätsstr. 30, 93040, Regensburg, Germany.
| | - Thomas Kuner
- Department of Functional Neuroanatomy, Institute for Anatomy and Cell Biology, Heidelberg University, Im Neuenheimer Feld 307, 69120, Heidelberg, Germany
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22
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Wang J, Tian Y, Zeng LH, Xu H. Prefrontal Disinhibition in Social Fear: A Vital Action of Somatostatin Interneurons. Front Cell Neurosci 2020; 14:611732. [PMID: 33390908 PMCID: PMC7773700 DOI: 10.3389/fncel.2020.611732] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 11/27/2020] [Indexed: 12/18/2022] Open
Abstract
Social fear and avoidance of social partners and social situations represent the core behavioral symptom of Social Anxiety Disorder (SAD), a prevalent psychiatric disorder worldwide. The pathological mechanism of SAD remains elusive and there are no specific and satisfactory therapeutic options currently available. With the development of appropriate animal models, growing studies start to unravel neuronal circuit mechanisms underlying social fear, and underscore a fundamental role of the prefrontal cortex (PFC). Prefrontal cortical functions are implemented by a finely wired microcircuit composed of excitatory principal neurons (PNs) and diverse subtypes of inhibitory interneurons (INs). Disinhibition, defined as a break in inhibition via interactions between IN subtypes that enhances the output of excitatory PNs, has recently been discovered to serve as an efficient strategy in cortical information processing. Here, we review the rodent animal models of social fear, the prefrontal IN diversity, and their circuits with a particular emphasis on a novel disinhibitory microcircuit mediated by somatostatin-expressing INs in gating social fear behavior. The INs subtype distinct and microcircuit-based mechanism advances our understanding of the etiology of social fear and sheds light on developing future treatment of neuropsychiatric disorders associated with social fear.
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Affiliation(s)
- Jun Wang
- Department of Neurobiology and Department of Neurology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, China
| | - Yuanyuan Tian
- Department of Neurobiology and Department of Neurology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, China
| | - Ling-Hui Zeng
- Department of Pharmacology, School of Medicine, Zhejiang University City College, Hangzhou, China
| | - Han Xu
- Department of Neurobiology and Department of Neurology of the Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China.,NHC and CAMS Key Laboratory of Medical Neurobiology, MOE Frontier Science Center for Brain Research and Brain-Machine Integration, School of Brain Science and Brain Medicine, Zhejiang University, Hangzhou, China.,Department of Pharmacology, School of Medicine, Zhejiang University City College, Hangzhou, China
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23
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Pérez-Revuelta L, Téllez de Meneses PG, López M, Briñón JG, Weruaga E, Díaz D, Alonso JR. Secretagogin expression in the mouse olfactory bulb under sensory impairments. Sci Rep 2020; 10:21533. [PMID: 33299042 PMCID: PMC7726155 DOI: 10.1038/s41598-020-78499-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 11/24/2020] [Indexed: 12/04/2022] Open
Abstract
The interneurons of the olfactory bulb (OB) are characterized by the expression of different calcium-binding proteins, whose specific functions are not fully understood. This is the case of one of the most recently discovered, the secretagogin (SCGN), which is expressed in interneurons of the glomerular and the granule cell layers, but whose function in the olfactory pathway is still unknown. To address this question, we examined the distribution, generation and activity of SCGN-positive interneurons in the OB of two complementary models of olfactory impairments: Purkinje Cell Degeneration (PCD) and olfactory-deprived mice. Our results showed a significant increase in the density of SCGN-positive cells in the inframitral layers of olfactory-deprived mice as compared to control animals. Moreover, BrdU analyses revealed that these additional SCGN-positive cells are not newly formed. Finally, the neuronal activity, estimated by c-Fos expression, increased in preexisting SCGN-positive interneurons of both deprived and PCD mice -being higher in the later- in comparison with control animals. Altogether, our results suggest that the OB possesses different compensatory mechanisms depending on the type of alteration. Particularly, the SCGN expression is dependent of olfactory stimuli and its function may be related to a compensation against a reduction in sensory inputs.
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Affiliation(s)
- L Pérez-Revuelta
- Laboratory of Neuronal Plasticity and Neurorepair, Institute for Neuroscience of Castile and Leon (INCyL), University of Salamanca, C/ Pintor Fernando Gallego, 1, 37007, Salamanca, Spain.,Institute of Biomedical Research of Salamanca, IBSAL, 37007, Salamanca, Spain
| | - P G Téllez de Meneses
- Laboratory of Neuronal Plasticity and Neurorepair, Institute for Neuroscience of Castile and Leon (INCyL), University of Salamanca, C/ Pintor Fernando Gallego, 1, 37007, Salamanca, Spain.,Institute of Biomedical Research of Salamanca, IBSAL, 37007, Salamanca, Spain
| | - M López
- Laboratory of Neuronal Plasticity and Neurorepair, Institute for Neuroscience of Castile and Leon (INCyL), University of Salamanca, C/ Pintor Fernando Gallego, 1, 37007, Salamanca, Spain.,Institute of Biomedical Research of Salamanca, IBSAL, 37007, Salamanca, Spain
| | - J G Briñón
- Laboratory of Neuronal Plasticity and Neurorepair, Institute for Neuroscience of Castile and Leon (INCyL), University of Salamanca, C/ Pintor Fernando Gallego, 1, 37007, Salamanca, Spain.,Institute of Biomedical Research of Salamanca, IBSAL, 37007, Salamanca, Spain
| | - E Weruaga
- Laboratory of Neuronal Plasticity and Neurorepair, Institute for Neuroscience of Castile and Leon (INCyL), University of Salamanca, C/ Pintor Fernando Gallego, 1, 37007, Salamanca, Spain.,Institute of Biomedical Research of Salamanca, IBSAL, 37007, Salamanca, Spain
| | - D Díaz
- Laboratory of Neuronal Plasticity and Neurorepair, Institute for Neuroscience of Castile and Leon (INCyL), University of Salamanca, C/ Pintor Fernando Gallego, 1, 37007, Salamanca, Spain. .,Institute of Biomedical Research of Salamanca, IBSAL, 37007, Salamanca, Spain.
| | - J R Alonso
- Laboratory of Neuronal Plasticity and Neurorepair, Institute for Neuroscience of Castile and Leon (INCyL), University of Salamanca, C/ Pintor Fernando Gallego, 1, 37007, Salamanca, Spain.,Institute of Biomedical Research of Salamanca, IBSAL, 37007, Salamanca, Spain
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24
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Activation of Granule Cell Interneurons by Two Divergent Local Circuit Pathways in the Rat Olfactory Bulb. J Neurosci 2020; 40:9701-9714. [PMID: 33234611 DOI: 10.1523/jneurosci.0989-20.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2020] [Revised: 10/17/2020] [Accepted: 10/21/2020] [Indexed: 02/07/2023] Open
Abstract
The olfactory bulb (OB) serves as a relay region for sensory information transduced by receptor neurons in the nose and ultimately routed to a variety of cortical areas. Despite the highly structured organization of the sensory inputs to the OB, even simple monomolecular odors activate large regions of the OB comprising many glomerular modules defined by afferents from different receptor neuron subtypes. OB principal cells receive their primary excitatory input from only one glomerular channel defined by inputs from one class of olfactory receptor neurons. By contrast, interneurons, such as GABAergic granule cells (GCs), integrate across multiple channels through dendodendritic inputs on their distal apical dendrites. Through their inhibitory synaptic actions, GCs appear to modulate principal cell firing to enhance olfactory discrimination, although how GCs contribute to olfactory function is not well understood. In this study, we identify a second synaptic pathway by which principal cells in the rat (both sexes) OB excite GCs by evoking potent nondepressing EPSPs (termed large-amplitude, nondendrodendritic [LANDD] EPSPs). LANDD EPSPs show little depression in response to tetanic stimulation and, therefore, can be distinguished other EPSPs that target GCs. LANDD EPSPs can be evoked by both focal stimulation near GC proximal dendrites and by activating sensory inputs in the glomerular layer in truncated GCs lacking dendrodendritic inputs. Using computational simulations, we show that LANDD EPSPs more reliably encode the duration of principal cell discharges than DD EPSPs, enabling GCs to compare contrasting versions of odor-driven activity patterns.SIGNIFICANCE STATEMENT The olfactory bulb plays a critical role in transforming broad sensory input patterns into odor-selective population responses. How this occurs is not well understood, but the local bulbar interneurons appear to be centrally involved in the process. Granule cells, the most common interneuron in the olfactory bulb, are known to broadly integrate sensory input through specialized synapses on their distal dendrites. Here we describe a second class of local excitatory inputs to granule cells that are more powerful than distal inputs and fail to depress with repeated stimulation. This second, proximal pathway allows bulbar interneurons to assay divergent versions of the same sensory input pattern.
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25
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Tsuboi A. LRR-Containing Oncofetal Trophoblast Glycoprotein 5T4 Shapes Neural Circuits in Olfactory and Visual Systems. Front Mol Neurosci 2020; 13:581018. [PMID: 33192298 PMCID: PMC7655536 DOI: 10.3389/fnmol.2020.581018] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 09/22/2020] [Indexed: 01/19/2023] Open
Abstract
In mammals, the sensory experience can regulate the development of various brain structures, including the cortex, hippocampus, retina, and olfactory bulb (OB). Odor experience-evoked neural activity drives the development of dendrites on excitatory projection neurons in the OB, such as mitral and tufted cells, as well as inhibitory interneurons. OB interneurons are generated continuously in the subventricular zone and differentiate into granule cells (GCs) and periglomerular cells (PGCs). However, it remains unknown what role each type of OB interneuron plays in controlling olfactory behaviors. Recent studies showed that among the various types of OB interneurons, a subtype of GCs expressing oncofetal trophoblast glycoprotein 5T4 is required for simple odor detection and discrimination behaviors. Mouse 5T4 (also known as Tpbg) is a type I membrane glycoprotein whose extracellular domain contains seven leucine-rich repeats (LRRs) sandwiched between characteristic LRR-N and LRR-C regions. Recently, it was found that the developmental expression of 5T4 increases dramatically in the retina just before eye-opening. Single-cell transcriptomics further suggests that 5T4 is involved in the development and maintenance of functional synapses in a subset of retinal interneurons, including rod bipolar cells (RBCs) and amacrine cells (ACs). Collectively, 5T4, expressed in interneurons of the OB and retina, plays a key role in sensory processing in the olfactory and visual systems.
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Affiliation(s)
- Akio Tsuboi
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
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26
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Hu B, Jin C, Zhang YQ, Miao HR, Wang F. In vivo odorant input induces distinct synaptic plasticity of GABAergic synapses in developing zebrafish olfactory bulb. Biochem Biophys Res Commun 2020; 531:160-165. [PMID: 32782153 DOI: 10.1016/j.bbrc.2020.07.106] [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: 06/29/2020] [Accepted: 07/22/2020] [Indexed: 02/07/2023]
Abstract
In the first station of central odor processing, the main olfactory bulb, signal processing is regulated by synaptic interactions between glutamatergic and GABAergic inputs of the mitral cells (MCs), the major projection neurons. Our previous study has found that repetitive postsynaptic spiking within a critical time window after presynaptic activation by natural odorant stimulation results in persistent enhancement of glutamatergic inputs of MCs in larval zebrafish. Here we observed a long-term depression of GABAergic synapses induced by the same protocol. This long-term depression was mediated by presynaptic NMDA receptors (NMDARs). Further dissecting GABAergic neurotransmission revealed that the STDP-induction protocol induced persistent modification in recurrent and lateral inhibition with opposite directions and distinct requirements on NMDARs. Thus, at the plasticity level, different types of GABAergic inhibition may utilize different mechanisms to cooperate or compete with excitatory inputs to optimize patterns of olfactory bulb output.
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Affiliation(s)
- Bin Hu
- Research Center for Biochemistry and Molecular Biology, Jiangsu Key Laboratory of Brain Disease Bioinformation, Xuzhou Medical University, Xuzhou, Jiangsu, 221004, China; Department of Neurobiology, School of Basic Medical Sciences, Nanjing Medical University, Nanjing, Jiangsu, 211166, China
| | - Chen Jin
- Research Center for Biochemistry and Molecular Biology, Jiangsu Key Laboratory of Brain Disease Bioinformation, Xuzhou Medical University, Xuzhou, Jiangsu, 221004, China
| | - Yi-Qian Zhang
- Department of Thoracic Cardiovascular Surgery, The Eighth Affiliated Hospital of Sun Yat-sen University, Shenzhen, Guangdong, 518033, China
| | - Hao-Ran Miao
- Department of Thoracic Cardiovascular Surgery, The Eighth Affiliated Hospital of Sun Yat-sen University, Shenzhen, Guangdong, 518033, China
| | - Feng Wang
- Neurology Department, Seventh People's Hospital of Shanghai, University of Traditional Chinese Medicine, Shanghai, 200137, China.
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27
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Wang D, Chen Y, Chen Y, Li X, Liu P, Yin Z, Li A. Improved Separation of Odor Responses in Granule Cells of the Olfactory Bulb During Odor Discrimination Learning. Front Cell Neurosci 2020; 14:579349. [PMID: 33192325 PMCID: PMC7581703 DOI: 10.3389/fncel.2020.579349] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Accepted: 09/14/2020] [Indexed: 01/01/2023] Open
Abstract
In the olfactory bulb, olfactory information is translated into ensemble representations by mitral/tufted cells, and these representations change dynamically in a context-dependent manner. In particular, odor representations in mitral/tufted cells display pattern separation during odor discrimination learning. Although granule cells provide major inhibitory input to mitral/tufted cells and play an important role in pattern separation and olfactory learning, the dynamics of odor responses in granule cells during odor discrimination learning remain largely unknown. Here, we studied odor responses in granule cells of the olfactory bulb using fiber photometry recordings in awake behaving mice. We found that odors evoked reliable, excitatory responses in the granule cell population. Intriguingly, during odor discrimination learning, odor responses in granule cells exhibited improved separation and contained information about odor value. In conclusion, we show that granule cells in the olfactory bulb display learning-related plasticity, suggesting that they may mediate pattern separation in mitral/tufted cells.
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Affiliation(s)
- Dejuan Wang
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Yang Chen
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Yiling Chen
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Xiaowen Li
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Penglai Liu
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Zhaoyang Yin
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
| | - Anan Li
- Jiangsu Key Laboratory of Brain Disease and Bioinformation, Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Xuzhou, China
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28
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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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29
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Chen Z, Padmanabhan K. Top-Down Control of Inhibitory Granule Cells in the Main Olfactory Bulb Reshapes Neural Dynamics Giving Rise to a Diversity of Computations. Front Comput Neurosci 2020; 14:59. [PMID: 32765248 PMCID: PMC7381246 DOI: 10.3389/fncom.2020.00059] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 05/22/2020] [Indexed: 01/05/2023] Open
Abstract
Growing evidence shows that top-down projections from excitatory neurons in piriform cortex selectively synapse onto local inhibitory granule cells in the main olfactory bulb, effectively gating their own inputs by controlling inhibition. An open question in olfaction is the role this feedback plays in shaping the dynamics of local circuits, and the resultant computational benefits it provides. Using rate models of neuronal firing in a network consisting of excitatory mitral and tufted cells, inhibitory granule cells and top-down piriform cortical neurons, we found that changes in the weight of feedback to inhibitory neurons generated diverse network dynamics and complex transitions between these dynamics. Changes in the weight of top-down feedback supported a number of computations, including both pattern separation and oscillatory synchrony. Additionally, the network could generate gamma oscillations though a mechanism we termed Top-down control of Inhibitory Neuron Gamma (TING). Collectively, these functions arose from a codimension-2 bifurcation in the dynamical system. Our results highlight a key role for this top-down feedback, gating inhibition to facilitate often diametrically different computations.
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Affiliation(s)
- Zhen Chen
- Department of Brain and Cognitive Sciences, University of Rochester, Rochester, NY, United States
| | - Krishnan Padmanabhan
- Department of Neuroscience, University of Rochester School of Medicine and Dentistry, Rochester, NY, United States
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30
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Mitf Links Neuronal Activity and Long-Term Homeostatic Intrinsic Plasticity. eNeuro 2020; 7:ENEURO.0412-19.2020. [PMID: 32193365 PMCID: PMC7174873 DOI: 10.1523/eneuro.0412-19.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 02/07/2020] [Accepted: 03/02/2020] [Indexed: 12/25/2022] Open
Abstract
Neuroplasticity forms the basis for neuronal circuit complexity and differences between otherwise similar circuits. We show that the microphthalmia-associated transcription factor (Mitf) plays a central role in intrinsic plasticity of olfactory bulb (OB) projection neurons. Mitral and tufted (M/T) neurons from Mitf mutant mice are hyperexcitable, have a reduced A-type potassium current (IA) and exhibit reduced expression of Kcnd3, which encodes a potassium voltage-gated channel subunit (Kv4.3) important for generating the IA Furthermore, expression of the Mitf and Kcnd3 genes is activity dependent in OB projection neurons and the MITF protein activates expression from Kcnd3 regulatory elements. Moreover, Mitf mutant mice have changes in olfactory habituation and have increased habituation for an odorant following long-term exposure, indicating that regulation of Kcnd3 is pivotal for long-term olfactory adaptation. Our findings show that Mitf acts as a direct regulator of intrinsic homeostatic feedback and links neuronal activity, transcriptional changes and neuronal function.
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31
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Dalal T, Gupta N, Haddad R. Bilateral and unilateral odor processing and odor perception. Commun Biol 2020; 3:150. [PMID: 32238904 PMCID: PMC7113286 DOI: 10.1038/s42003-020-0876-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Accepted: 03/05/2020] [Indexed: 11/09/2022] Open
Abstract
Imagine smelling a novel perfume with only one nostril and then smelling it again with the other nostril. Clearly, you can tell that it is the same perfume both times. This simple experiment demonstrates that odor information is shared across both hemispheres to enable perceptual unity. In many sensory systems, perceptual unity is believed to be mediated by inter-hemispheric connections between iso-functional cortical regions. However, in the olfactory system, the underlying neural mechanisms that enable this coordination are unclear because the two olfactory cortices are not topographically organized and do not seem to have homotypic inter-hemispheric mapping. This review presents recent advances in determining which aspects of odor information are processed unilaterally or bilaterally, and how odor information is shared across the two hemispheres. We argue that understanding the mechanisms of inter-hemispheric coordination can provide valuable insights that are hard to achieve when focusing on one hemisphere alone.
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Affiliation(s)
- Tal Dalal
- The Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan, 5290002, Israel
| | - Nitin Gupta
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur, Uttar Pradesh, 208016, India
| | - Rafi Haddad
- The Gonda Multidisciplinary Brain Research Center, Bar-Ilan University, Ramat-Gan, 5290002, Israel.
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32
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Wu A, Yu B, Komiyama T. Plasticity in olfactory bulb circuits. Curr Opin Neurobiol 2020; 64:17-23. [PMID: 32062045 DOI: 10.1016/j.conb.2020.01.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Revised: 11/27/2019] [Accepted: 01/15/2020] [Indexed: 12/24/2022]
Abstract
Olfaction is crucial for animal survival and human well-being. The olfactory bulb is the obligatory input station for olfactory information. In contrast to the traditional view as a static relay station, recent evidence indicates that the olfactory bulb dynamically processes olfactory information in an experience-dependent and context-dependent manner. Here, we review recent studies on experience-dependent plasticity of the main circuit components within the olfactory bulb of rodents. We argue that the olfactory bulb plasticity allows optimal representations of behaviorally-relevant odors in the continuously changing olfactory environment.
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Affiliation(s)
- An Wu
- Neurobiology Section, Center for Neural Circuits and Behavior, University of California San Diego, La Jolla, CA 92093, USA; Department of Neurosciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Bin Yu
- Neurobiology Section, Center for Neural Circuits and Behavior, University of California San Diego, La Jolla, CA 92093, USA; Department of Neurosciences, University of California San Diego, La Jolla, CA 92093, USA; Department of Electrical and Computer Engineering, University of California San Diego, La Jolla, CA 92093, USA
| | - Takaki Komiyama
- Neurobiology Section, Center for Neural Circuits and Behavior, University of California San Diego, La Jolla, CA 92093, USA; Department of Neurosciences, University of California San Diego, La Jolla, CA 92093, USA.
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33
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Goaillard JM, Moubarak E, Tapia M, Tell F. Diversity of Axonal and Dendritic Contributions to Neuronal Output. Front Cell Neurosci 2020; 13:570. [PMID: 32038171 PMCID: PMC6987044 DOI: 10.3389/fncel.2019.00570] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 12/09/2019] [Indexed: 11/13/2022] Open
Abstract
Our general understanding of neuronal function is that dendrites receive information that is transmitted to the axon, where action potentials (APs) are initiated and propagated to eventually trigger neurotransmitter release at synaptic terminals. Even though this canonical division of labor is true for a number of neuronal types in the mammalian brain (including neocortical and hippocampal pyramidal neurons or cerebellar Purkinje neurons), many neuronal types do not comply with this classical polarity scheme. In fact, dendrites can be the site of AP initiation and propagation, and even neurotransmitter release. In several interneuron types, all functions are carried out by dendrites as these neurons are devoid of a canonical axon. In this article, we present a few examples of "misbehaving" neurons (with a non-canonical polarity scheme) to highlight the diversity of solutions that are used by mammalian neurons to transmit information. Moreover, we discuss how the contribution of dendrites and axons to neuronal excitability may impose constraints on the morphology of these compartments in specific functional contexts.
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Affiliation(s)
- Jean-Marc Goaillard
- UMR_S 1072, Aix Marseille Université, INSERM, Faculté de Médecine Secteur Nord, Marseille, France
| | - Estelle Moubarak
- UMR_S 1072, Aix Marseille Université, INSERM, Faculté de Médecine Secteur Nord, Marseille, France
| | - Mónica Tapia
- UMR_S 1072, Aix Marseille Université, INSERM, Faculté de Médecine Secteur Nord, Marseille, France
| | - Fabien Tell
- UMR_S 1072, Aix Marseille Université, INSERM, Faculté de Médecine Secteur Nord, Marseille, France
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34
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Reinert JK, Schaefer AT, Kuner T. High-Throughput Automated Olfactory Phenotyping of Group-Housed Mice. Front Behav Neurosci 2019; 13:267. [PMID: 31920577 PMCID: PMC6927946 DOI: 10.3389/fnbeh.2019.00267] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 11/25/2019] [Indexed: 11/13/2022] Open
Abstract
Behavioral phenotyping of mice is often compromised by manual interventions of the experimenter and limited throughput. Here, we describe a fully automated behavior setup that allows for quantitative analysis of mouse olfaction with minimized experimenter involvement. Mice are group-housed and tagged with unique RFID chips. They can freely initiate trials and are automatically trained on a go/no-go task, learning to distinguish a rewarded from an unrewarded odor. Further, odor discrimination tasks and detailed training aspects can be set for each animal individually for automated execution without direct experimenter intervention. The procedure described here, from initial RFID implantation to discrimination of complex odor mixtures at high accuracy, can be completed within <2 months with cohorts of up to 25 male mice. Apart from the presentation of monomolecular odors, the setup can generate arbitrary mixtures and dilutions from any set of odors to create complex stimuli, enabling demanding behavioral analyses at high-throughput.
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Affiliation(s)
- Janine K. Reinert
- Institute of Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
| | - Andreas T. Schaefer
- Institute of Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
- Neurophysiology of Behaviour Laboratory, The Francis Crick Institute, London, United Kingdom
- Department of Neuroscience, Physiology and Pharmacology, University College London, London, United Kingdom
| | - Thomas Kuner
- Institute of Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
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35
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Notsu E, Toida K. Examination of morphological and synaptic features of calbindin-immunoreactive neurons in deep layers of the rat olfactory bulb with correlative laser and volume electron microscopy. Microscopy (Oxf) 2019; 68:316-329. [PMID: 31062844 DOI: 10.1093/jmicro/dfz019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2019] [Revised: 03/21/2019] [Accepted: 04/09/2019] [Indexed: 06/09/2023] Open
Abstract
The olfactory bulb (OB) contains various interneuron types that play key roles in processing olfactory information via synaptic contacts. Many previous studies have reported synaptic connections of heterogeneous interneurons in superficial OB layers. In contrast, few studies have examined synaptic connections in deep layers because of the lack of a selective marker for intrinsic neurons located in the deeper layers, including the mitral cell layer, internal plexiform layer (IPL) and granule cell layer. However, neural circuits in the deep layers are likely to have a strong effect on the output of the OB because of the cellular composition of these regions. Here, we analyzed the calbindin-immunoreactive neurons in the IPL, one of the clearly neurochemically defined interneuron types in the deep layers, using multiple immunolabeling and confocal laser scanning microscopy combined with electron microscopic three-dimensional serial-section reconstruction, enabling correlated laser and volume electron microscopy (EM). Despite a resemblance to the morphological features of deep short axon cells, IPL calbindin-immunoreactive (IPL-CB-ir) neurons lacked axons. Furthermore, multiple immunolabeling for plural neurochemicals indicated that IPL-CB-ir neurons differed from any interneuron types reported previously. We identified symmetrical synapses formed by IPL-CB-ir neurons on granule cells (GCs) using correlated laser and volume EM. These synapses might inhibit GCs and thus disinhibit mitral and tufted cells. Our present findings indicate, for the first time, that IPL-CB-ir neurons are involved in regulating the activities of projection neurons, further suggesting their involvement in synaptic circuitry for output from the deeper layers of the OB, which has not previously been clarified.
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Affiliation(s)
- Eiji Notsu
- Department of Anatomy, Kawasaki Medical School, Kurashiki, Okayama 701-0192, Japan
| | - Kazunori Toida
- Department of Anatomy, Kawasaki Medical School, Kurashiki, Okayama 701-0192, Japan
- Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, Ibaraki, Osaka 567-0047, Japan
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36
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Bragado Alonso S, Reinert JK, Marichal N, Massalini S, Berninger B, Kuner T, Calegari F. An increase in neural stem cells and olfactory bulb adult neurogenesis improves discrimination of highly similar odorants. EMBO J 2019; 38:e98791. [PMID: 30643018 PMCID: PMC6418468 DOI: 10.15252/embj.201798791] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Revised: 11/14/2018] [Accepted: 11/15/2018] [Indexed: 01/17/2023] Open
Abstract
Adult neurogenesis is involved in cognitive performance but studies that manipulated this process to improve brain function are scarce. Here, we characterized a genetic mouse model in which neural stem cells (NSC) of the subventricular zone (SVZ) were temporarily expanded by conditional expression of the cell cycle regulators Cdk4/cyclinD1, thus increasing neurogenesis. We found that supernumerary neurons matured and integrated in the olfactory bulb similarly to physiologically generated newborn neurons displaying a correct expression of molecular markers, morphology and electrophysiological activity. Olfactory performance upon increased neurogenesis was unchanged when mice were tested on relatively easy tasks using distinct odor stimuli. In contrast, intriguingly, increasing neurogenesis improved the discrimination ability of mice when challenged with a difficult task using mixtures of highly similar odorants. Together, our study provides a mammalian model to control the expansion of somatic stem cells that can in principle be applied to any tissue for basic research and models of therapy. By applying this to NSC of the SVZ, we highlighted the importance of adult neurogenesis to specifically improve performance in a challenging olfactory task.
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Affiliation(s)
- Sara Bragado Alonso
- CRTD Center for Regenerative Therapies Dresden, School of Medicine, TU Dresden, Dresden, Germany
| | - Janine K Reinert
- Department of Functional Neuroanatomy, Institute for Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
| | - Nicolas Marichal
- Institute of Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
- Centre for Developmental Neurobiology and MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Simone Massalini
- CRTD Center for Regenerative Therapies Dresden, School of Medicine, TU Dresden, Dresden, Germany
| | - Benedikt Berninger
- Institute of Physiological Chemistry, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany
- Centre for Developmental Neurobiology and MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK
| | - Thomas Kuner
- Department of Functional Neuroanatomy, Institute for Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
| | - Federico Calegari
- CRTD Center for Regenerative Therapies Dresden, School of Medicine, TU Dresden, Dresden, Germany
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Donato A, Kagias K, Zhang Y, Hilliard MA. Neuronal sub-compartmentalization: a strategy to optimize neuronal function. Biol Rev Camb Philos Soc 2019; 94:1023-1037. [PMID: 30609235 PMCID: PMC6617802 DOI: 10.1111/brv.12487] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 11/21/2018] [Accepted: 11/23/2018] [Indexed: 12/14/2022]
Abstract
Neurons are highly polarized cells that consist of three main structural and functional domains: a cell body or soma, an axon, and dendrites. These domains contain smaller compartments with essential roles for proper neuronal function, such as the axonal presynaptic boutons and the dendritic postsynaptic spines. The structure and function of these compartments have now been characterized in great detail. Intriguingly, however, in the last decade additional levels of compartmentalization within the axon and the dendrites have been identified, revealing that these structures are much more complex than previously thought. Herein we examine several types of structural and functional sub-compartmentalization found in neurons of both vertebrates and invertebrates. For example, in mammalian neurons the axonal initial segment functions as a sub-compartment to initiate the action potential, to select molecules passing into the axon, and to maintain neuronal polarization. Moreover, work in Drosophila melanogaster has shown that two distinct axonal guidance receptors are precisely clustered in adjacent segments of the commissural axons both in vivo and in vitro, suggesting a cell-intrinsic mechanism underlying the compartmentalized receptor localization. In Caenorhabditis elegans, a subset of interneurons exhibits calcium dynamics that are localized to specific sections of the axon and control the gait of navigation, demonstrating a regulatory role of compartmentalized neuronal activity in behaviour. These findings have led to a number of new questions, which are important for our understanding of neuronal development and function. How are these sub-compartments established and maintained? What molecular machinery and cellular events are involved? What is their functional significance for the neuron? Here, we reflect on these and other key questions that remain to be addressed in this expanding field of biology.
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Affiliation(s)
- Alessandra Donato
- Clem Jones Centre for Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
| | - Konstantinos Kagias
- Department of Organismic and Evolutionary Biology, Center for Brain Science, Harvard University, Cambridge, MA 02138, U.S.A
| | - Yun Zhang
- Department of Organismic and Evolutionary Biology, Center for Brain Science, Harvard University, Cambridge, MA 02138, U.S.A
| | - Massimo A Hilliard
- Clem Jones Centre for Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia
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Daghfous G, Auclair F, Clotten F, Létourneau JL, Atallah E, Millette JP, Derjean D, Robitaille R, Zielinski BS, Dubuc R. GABAergic modulation of olfactomotor transmission in lampreys. PLoS Biol 2018; 16:e2005512. [PMID: 30286079 PMCID: PMC6191151 DOI: 10.1371/journal.pbio.2005512] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Revised: 10/16/2018] [Accepted: 09/18/2018] [Indexed: 12/21/2022] Open
Abstract
Odor-guided behaviors, including homing, predator avoidance, or food and mate searching, are ubiquitous in animals. It is only recently that the neural substrate underlying olfactomotor behaviors in vertebrates was uncovered in lampreys. It consists of a neural pathway extending from the medial part of the olfactory bulb (medOB) to locomotor control centers in the brainstem via a single relay in the caudal diencephalon. This hardwired olfactomotor pathway is present throughout life and may be responsible for the olfactory-induced motor behaviors seen at all life stages. We investigated modulatory mechanisms acting on this pathway by conducting anatomical (tract tracing and immunohistochemistry) and physiological (intracellular recordings and calcium imaging) experiments on lamprey brain preparations. We show that the GABAergic circuitry of the olfactory bulb (OB) acts as a gatekeeper of this hardwired sensorimotor pathway. We also demonstrate the presence of a novel olfactomotor pathway that originates in the non-medOB and consists of a projection to the lateral pallium (LPal) that, in turn, projects to the caudal diencephalon and to the mesencephalic locomotor region (MLR). Our results indicate that olfactory inputs can induce behavioral responses by activating brain locomotor centers via two distinct pathways that are strongly modulated by GABA in the OB. The existence of segregated olfactory subsystems in lampreys suggests that the organization of the olfactory system in functional clusters may be a common ancestral trait of vertebrates.
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Affiliation(s)
- Gheylen Daghfous
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
- Groupe de Recherche en Activité Physique Adaptée, Département des sciences de l'activité physique, Université du Québec à Montréal, Montréal, Québec, Canada
| | - François Auclair
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
| | - Felix Clotten
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
| | - Jean-Luc Létourneau
- Groupe de Recherche en Activité Physique Adaptée, Département des sciences de l'activité physique, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Elias Atallah
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
| | - Jean-Patrick Millette
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
| | - Dominique Derjean
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
- Groupe de Recherche en Activité Physique Adaptée, Département des sciences de l'activité physique, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Richard Robitaille
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
| | - Barbara S. Zielinski
- Department of Biological Sciences, University of Windsor, Windsor, Ontario, Canada
- Great Lakes Institute for Environmental Research, University of Windsor, Windsor, Ontario, Canada
| | - Réjean Dubuc
- Groupe de Recherche sur le Système Nerveux Central, Département de neurosciences, Université de Montréal, Montréal, Québec, Canada
- Groupe de Recherche en Activité Physique Adaptée, Département des sciences de l'activité physique, Université du Québec à Montréal, Montréal, Québec, Canada
- * E-mail:
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Nunes D, Kuner T. Axonal sodium channel NaV1.2 drives granule cell dendritic GABA release and rapid odor discrimination. PLoS Biol 2018; 16:e2003816. [PMID: 30125271 PMCID: PMC6117082 DOI: 10.1371/journal.pbio.2003816] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 08/30/2018] [Accepted: 08/06/2018] [Indexed: 12/19/2022] Open
Abstract
Dendrodendritic synaptic interactions between olfactory bulb mitral and granule cells represent a key neuronal mechanism of odor discrimination. Dendritic release of gamma-aminobutyric acid (GABA) from granule cells contributes to stimulus-dependent, rapid, and accurate odor discrimination, yet the physiological mechanisms governing this release and its behavioral relevance are unknown. Here, we show that granule cells express the voltage-gated sodium channel α-subunit NaV1.2 in clusters distributed throughout the cell surface including dendritic spines. Deletion of NaV1.2 in granule cells abolished spiking and GABA release as well as inhibition of synaptically connected mitral cells (MCs). As a consequence, mice required more time to discriminate highly similar odorant mixtures, while odor discrimination learning remained unaffected. In conclusion, we show that expression of NaV1.2 in granule cells is crucial for physiological dendritic GABA release and rapid discrimination of similar odorants with high accuracy. Hence, our data indicate that neurotransmitter-releasing dendritic spines function just like axon terminals. In axonal nerve terminals, neurotransmitter release is triggered by a localized Ca2+ nanodomain generated by voltage-gated calcium channels in response to an action potential, which in turn is mediated by voltage-gated sodium channels. Dendritic neurotransmitter release has been thought to work differently, mainly depending on Ca2+ entering directly through N-methyl-D-aspartate (NMDA) receptors, a subtype of ligand-gated ion channel. To further investigate how dendritic neurotransmitter is released, we studied granule cells in the olfactory bulb of mice, which establish inhibitory dendrodendritic synapses with mitral cells. We show that granule cells express voltage-gated sodium channels predominantly localized in dendrites and spines. Down-regulation of these channels precludes action potential firing in granule cells and strongly reduces mitral cell inhibition. Behaviorally, these mice require more time to discriminate highly similar odorants at maximal accuracy. Therefore, the inhibition of mitral cells relies on neurotransmitter released from the dendrites of granule cells by a mechanism that resembles axonal neurotransmitter release much more than previously thought.
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Affiliation(s)
- Daniel Nunes
- Champalimaud Research, Champalimaud Centre for the Unknown, Lisbon, Portugal
- Functional Neuroanatomy Department, Institute for Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
- * E-mail: (DN); (TK)
| | - Thomas Kuner
- Functional Neuroanatomy Department, Institute for Anatomy and Cell Biology, Heidelberg University, Heidelberg, Germany
- * E-mail: (DN); (TK)
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Takahashi H, Yoshihara S, Tsuboi A. The Functional Role of Olfactory Bulb Granule Cell Subtypes Derived From Embryonic and Postnatal Neurogenesis. Front Mol Neurosci 2018; 11:229. [PMID: 30034321 PMCID: PMC6043811 DOI: 10.3389/fnmol.2018.00229] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Accepted: 06/12/2018] [Indexed: 02/01/2023] Open
Abstract
It has been shown in a variety of mammalian species that sensory experience can regulate the development of various structures, including the retina, cortex, hippocampus, and olfactory bulb (OB). In the mammalian OB, the development of dendrites in excitatory projection neurons, such as mitral and tufted cells, is well known to be dependent on odor experience. Odor experience is also involved in the development of another OB population, a subset of inhibitory interneurons that are generated in the ventricular-subventricular zone throughout life and differentiate into granule cells (GCs) and periglomerular cells. However, the roles that each type of interneuron plays in the control of olfactory behaviors are incompletely understood. We recently found that among the various types of OB interneurons, a subtype of GCs expressing the oncofetal trophoblast glycoprotein 5T4 gene is required for odor detection and discrimination behaviors. Our results suggest that embryonic-born OB interneurons, including 5T4-positive GCs, play a crucial role in fundamental olfactory responses such as simple odor detection and discrimination behaviors. By contrast, postnatal- and adult-born OB interneurons are important in the learning of more complicated olfactory behaviors. Here, we highlight the subtypes of OB GCs, and discuss their roles in olfactory processing and behavior, with a particular focus on the relative contributions of embryonically and postnatally generated subsets of GCs in rodents.
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Affiliation(s)
- Hiroo Takahashi
- Laboratory for the Molecular Biology of Neural Systems, Advanced Medical Research Center, Nara Medical University, Kashihara, Japan
| | - Seiichi Yoshihara
- Laboratory for the Molecular Biology of Neural Systems, Advanced Medical Research Center, Nara Medical University, Kashihara, Japan
| | - Akio Tsuboi
- Laboratory for the Molecular Biology of Neural Systems, Advanced Medical Research Center, Nara Medical University, Kashihara, Japan.,Laboratory for the Molecular and Cellular Neuroscience, Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
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The role of calretinin-expressing granule cells in olfactory bulb functions and odor behavior. Sci Rep 2018; 8:9385. [PMID: 29925844 PMCID: PMC6010413 DOI: 10.1038/s41598-018-27692-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 06/08/2018] [Indexed: 12/12/2022] Open
Abstract
The adult mouse olfactory bulb is continuously supplied with new neurons that mostly differentiate into granule cells (GCs). Different subtypes of adult-born GCs have been identified, but their maturational profiles and their roles in bulbar network functioning and odor behavior remain elusive. It is also not known whether the same subpopulations of GCs born during early postnatal life (early-born) or during adulthood (adult-born) differ in their morpho-functional properties. Here, we show that adult-born calretinin-expressing (CR+) and non-expressing (CR−) GCs, as well as early-born CR+ GCs, display distinct inhibitory inputs but indistinguishable excitatory inputs and similar morphological characteristics. The frequencies of inhibitory post-synaptic currents were lower in early-born and adult-born CR+ GCs than in adult-born CR− neurons. These findings were corroborated by the reduced density of gephyrin+ puncta on CR+ GCs. CR+ GCs displayed a higher level of activation following olfactory tasks based on odor discrimination, as determined by an immediate early gene expression analysis. Pharmacogenetic inhibition of CR+ GCs diminished the ability of the mice to discriminate complex odor mixtures. Altogether, our results indicate that distinct inhibitory inputs are received by adult-born CR+ and CR− GCs, that early- and adult-born CR+ neurons have similar morpho-functional properties, and that CR+ GCs are involved in complex odor discrimination tasks.
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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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Lukas M, Holthoff K, Egger V. Long-Term Plasticity at the Mitral and Tufted Cell to Granule Cell Synapse of the Olfactory Bulb Investigated with a Custom Multielectrode in Acute Brain Slice Preparations. Methods Mol Biol 2018; 1820:157-167. [PMID: 29884945 DOI: 10.1007/978-1-4939-8609-5_13] [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: 12/28/2022]
Abstract
Single extracellular stimulation electrodes are a widespread means to locally activate synaptic inputs in acute brain slices. Here we describe the fabrication and application of a multielectrode stimulator that was developed for conditions under which independent stimulation of several nearby sites is desirable. For the construction of the multielectrode we have developed a method by which electrode wires can be spaced at minimal distances of 100 μm. This configuration increases the efficiency of stimulation paradigms, such as the comparison of proximal induced and control inputs for studies of synaptic plasticity.In our case the multielectrode was used for acute olfactory bulb slices to independently excite individual nearby glomeruli; the technique allowed us to demonstrate homosynaptic bidirectional long-term plasticity at the mitral/tufted cell to granule cell synapse. We also describe the determinants for successful recordings of long-term plasticity at this synapse, with mechanical and electrophysiological recording stability being tantamount. Finally, we briefly discuss data analysis procedures.
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Affiliation(s)
- Michael Lukas
- Institute of Zoology and Regensburg Center of Neuroscience, Regensburg University, Regensburg, Germany
| | - Knut Holthoff
- Hans-Berger Department of Neurology, University Hospital Jena, Jena, Germany
| | - Veronica Egger
- Institute of Zoology and Regensburg Center of Neuroscience, Regensburg University, Regensburg, Germany.
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Malvaut S, Gribaudo S, Hardy D, David LS, Daroles L, Labrecque S, Lebel-Cormier MA, Chaker Z, Coté D, De Koninck P, Holzenberger M, Trembleau A, Caille I, Saghatelyan A. CaMKIIα Expression Defines Two Functionally Distinct Populations of Granule Cells Involved in Different Types of Odor Behavior. Curr Biol 2017; 27:3315-3329.e6. [PMID: 29107547 DOI: 10.1016/j.cub.2017.09.058] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 08/23/2017] [Accepted: 09/27/2017] [Indexed: 12/25/2022]
Abstract
Granule cells (GCs) in the olfactory bulb (OB) play an important role in odor information processing. Although they have been classified into various neurochemical subtypes, the functional roles of these subtypes remain unknown. We used in vivo two-photon Ca2+ imaging combined with cell-type-specific identification of GCs in the mouse OB to examine whether functionally distinct GC subtypes exist in the bulbar network. We showed that half of GCs express Ca2+/calmodulin-dependent protein kinase IIα (CaMKIIα+) and that these neurons are preferentially activated by olfactory stimulation. The higher activity of CaMKIIα+ neurons is due to the weaker inhibitory input that they receive compared to their CaMKIIα-immunonegative (CaMKIIα-) counterparts. In line with these functional data, immunohistochemical analyses showed that 75%-90% of GCs expressing the immediate early gene cFos are CaMKIIα+ in naive animals and in mice that have been exposed to a novel odor and go/no-go operant conditioning, or that have been subjected to long-term associative memory and spontaneous habituation/dishabituation odor discrimination tasks. On the other hand, a perceptual learning task resulted in increased activation of CaMKIIα- cells. Pharmacogenetic inhibition of CaMKIIα+ GCs revealed that this subtype is involved in habituation/dishabituation and go/no-go odor discrimination, but not in perceptual learning. In contrast, pharmacogenetic inhibition of GCs in a subtype-independent manner affected perceptual learning. Our results indicate that functionally distinct populations of GCs exist in the OB and that they play distinct roles during different odor tasks.
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Affiliation(s)
- Sarah Malvaut
- CERVO Brain Research Center, Quebec City, QC G1J 2G3, Canada
| | - Simona Gribaudo
- Sorbonne Universités, UPMC Université Paris 06, INSERM, CNRS, Institut de Biologie Paris Seine, Neuroscience Paris Seine, 75005 Paris, France
| | - Delphine Hardy
- CERVO Brain Research Center, Quebec City, QC G1J 2G3, Canada
| | | | - Laura Daroles
- Sorbonne Universités, UPMC Université Paris 06, INSERM, CNRS, Institut de Biologie Paris Seine, Neuroscience Paris Seine, 75005 Paris, France
| | - Simon Labrecque
- CERVO Brain Research Center, Quebec City, QC G1J 2G3, Canada
| | | | - Zayna Chaker
- INSERM and Sorbonne Universités, UPMC, Centre de Recherche Saint-Antoine, Paris, France
| | - Daniel Coté
- CERVO Brain Research Center, Quebec City, QC G1J 2G3, Canada; Faculté des Sciences et de Génie, Université Laval, Quebec City, QC G1V 0A6, Canada
| | - Paul De Koninck
- CERVO Brain Research Center, Quebec City, QC G1J 2G3, Canada; Faculté des Sciences et de Génie, Université Laval, Quebec City, QC G1V 0A6, Canada
| | - Martin Holzenberger
- INSERM and Sorbonne Universités, UPMC, Centre de Recherche Saint-Antoine, Paris, France
| | - Alain Trembleau
- Sorbonne Universités, UPMC Université Paris 06, INSERM, CNRS, Institut de Biologie Paris Seine, Neuroscience Paris Seine, 75005 Paris, France
| | - Isabelle Caille
- Sorbonne Universités, UPMC Université Paris 06, INSERM, CNRS, Institut de Biologie Paris Seine, Neuroscience Paris Seine, 75005 Paris, France; Université Paris Diderot, Sorbonne Paris Cité, 75013 Paris, France.
| | - Armen Saghatelyan
- CERVO Brain Research Center, Quebec City, QC G1J 2G3, Canada; Department of Psychiatry and Neuroscience, Université Laval, Quebec City, QC G1V 0A6, Canada.
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Burton SD. Inhibitory circuits of the mammalian main olfactory bulb. J Neurophysiol 2017; 118:2034-2051. [PMID: 28724776 DOI: 10.1152/jn.00109.2017] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Revised: 07/14/2017] [Accepted: 07/14/2017] [Indexed: 01/15/2023] Open
Abstract
Synaptic inhibition critically influences sensory processing throughout the mammalian brain, including the main olfactory bulb (MOB), the first station of sensory processing in the olfactory system. Decades of research across numerous laboratories have established a central role for granule cells (GCs), the most abundant GABAergic interneuron type in the MOB, in the precise regulation of principal mitral and tufted cell (M/TC) firing rates and synchrony through lateral and recurrent inhibitory mechanisms. In addition to GCs, however, the MOB contains a vast diversity of other GABAergic interneuron types, and recent findings suggest that, while fewer in number, these oft-ignored interneurons are just as important as GCs in shaping odor-evoked M/TC activity. Here I challenge the prevailing centrality of GCs. In this review, I first outline the specific properties of each GABAergic interneuron type in the rodent MOB, with particular emphasis placed on direct interneuron recordings and cell type-selective manipulations. On the basis of these properties, I then critically reevaluate the contribution of GCs vs. other interneuron types to the regulation of odor-evoked M/TC firing rates and synchrony via lateral, recurrent, and other inhibitory mechanisms. This analysis yields a novel model in which multiple interneuron types with distinct abundances, connectivity patterns, and physiologies complement one another to regulate M/TC activity and sensory processing.
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Affiliation(s)
- Shawn D Burton
- Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania; and .,Center for the Neural Basis of Cognition, Pittsburgh, Pennsylvania
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A Subtype of Olfactory Bulb Interneurons Is Required for Odor Detection and Discrimination Behaviors. J Neurosci 2017; 36:8210-27. [PMID: 27488640 DOI: 10.1523/jneurosci.2783-15.2016] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Accepted: 07/04/2016] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED Neural circuits that undergo reorganization by newborn interneurons in the olfactory bulb (OB) are necessary for odor detection and discrimination, olfactory memory, and innate olfactory responses, including predator avoidance and sexual behaviors. The OB possesses many interneurons, including various types of granule cells (GCs); however, the contribution that each type of interneuron makes to olfactory behavioral control remains unknown. Here, we investigated the in vivo functional role of oncofetal trophoblast glycoprotein 5T4, a regulator for dendritic arborization of 5T4-expressing GCs (5T4 GCs), the level of which is reduced in the OB of 5T4 knock-out (KO) mice. Electrophysiological recordings with acute OB slices indicated that external tufted cells (ETCs) can be divided into two types, bursting and nonbursting. Optogenetic stimulation of 5T4 GCs revealed their connection to both bursting and nonbursting ETCs, as well as to mitral cells (MCs). Interestingly, nonbursting ETCs received fewer inhibitory inputs from GCs in 5T4 KO mice than from those in wild-type (WT) mice, whereas bursting ETCs and MCs received similar inputs in both mice. Furthermore, 5T4 GCs received significantly fewer excitatory inputs in 5T4 KO mice. Remarkably, in olfactory behavior tests, 5T4 KO mice had higher odor detection thresholds than the WT, as well as defects in odor discrimination learning. Therefore, the loss of 5T4 attenuates inhibitory inputs from 5T4 GCs to nonbursting ETCs and excitatory inputs to 5T4 GCs, contributing to disturbances in olfactory behavior. Our novel findings suggest that, among the various types of OB interneurons, the 5T4 GC subtype is required for odor detection and discrimination behaviors. SIGNIFICANCE STATEMENT Neuronal circuits in the brain include glutamatergic principal neurons and GABAergic interneurons. Although the latter is a minority cell type, they are vital for normal brain function because they regulate the activity of principal neurons. If interneuron function is impaired, brain function may be damaged, leading to behavior disorder. The olfactory bulb (OB) possesses various types of interneurons, including granule cells (GCs); however, the contribution that each type of interneuron makes to the control of olfactory behavior remains unknown. Here, we analyzed electrophysiologically and behaviorally the function of oncofetal trophoblast glycoprotein 5T4, a regulator for dendritic branching in OB GCs. We found that, among the various types of OB interneuron, the 5T4 GC subtype is required for odor detection and odor discrimination behaviors.
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Hu B, Geng C, Hou XY. Oligomeric amyloid-β peptide disrupts olfactory information output by impairment of local inhibitory circuits in rat olfactory bulb. Neurobiol Aging 2016; 51:113-121. [PMID: 28061384 DOI: 10.1016/j.neurobiolaging.2016.12.005] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 11/22/2016] [Accepted: 12/05/2016] [Indexed: 11/27/2022]
Abstract
Although early olfactory dysfunction has been found in patients with Alzheimer's disease, the underlying mechanisms remain unclear. In this study, we investigated whether and how oligomeric amyloid-β peptide (Aβ) affects the responses of mitral cells (MCs). We found that oligomeric Aβ1-42 increased spontaneous and evoked firing rates but decreased the ratio of evoked to spontaneous firings in MCs. Aβ1-42 oligomers showed no impact on the hyperactivity exerted by pharmacological blockage of GABAA receptors, suggesting an involvement of GABAergic inhibitory transmission in Aβ1 to 42-induced over-excitability. It was further determined that Aβ1-42 oligomers inhibited the frequency of spontaneous inhibitory postsynaptic currents and miniature inhibitory postsynaptic currents, as well as the amplitude of miniature inhibitory postsynaptic currents in MCs. Both recurrent and lateral inhibition of MCs, which are critical for odor discrimination, were also disrupted by Aβ1-42 oligomers. The above data indicate that Aβ impairs local inhibitory circuits and thereby leads to perturbations of olfactory information output in the olfactory bulb. This study reveals a cellular and synaptic basis of olfactory deficits associated with Alzheimer's disease.
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Affiliation(s)
- Bin Hu
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Nanjing Medical University, Jiangsu, China; Jiangsu Key Laboratory of Brain Disease Bioinformation, Xuzhou Medical University, Jiangsu, China; Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Jiangsu, China
| | - Chi Geng
- Jiangsu Key Laboratory of Brain Disease Bioinformation, Xuzhou Medical University, Jiangsu, China; Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Jiangsu, China
| | - Xiao-Yu Hou
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Nanjing Medical University, Jiangsu, China; Jiangsu Key Laboratory of Brain Disease Bioinformation, Xuzhou Medical University, Jiangsu, China; Research Center for Biochemistry and Molecular Biology, Xuzhou Medical University, Jiangsu, China.
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48
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Sniff-Like Patterned Input Results in Long-Term Plasticity at the Rat Olfactory Bulb Mitral and Tufted Cell to Granule Cell Synapse. Neural Plast 2016; 2016:9124986. [PMID: 27747107 PMCID: PMC5056313 DOI: 10.1155/2016/9124986] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 06/13/2016] [Accepted: 06/28/2016] [Indexed: 11/17/2022] Open
Abstract
During odor sensing the activity of principal neurons of the mammalian olfactory bulb, the mitral and tufted cells (MTCs), occurs in repetitive bursts that are synchronized to respiration, reminiscent of hippocampal theta-gamma coupling. Axonless granule cells (GCs) mediate self- and lateral inhibitory interactions between the excitatory MTCs via reciprocal dendrodendritic synapses. We have explored long-term plasticity at this synapse by using a theta burst stimulation (TBS) protocol and variations thereof. GCs were excited via glomerular stimulation in acute brain slices. We find that TBS induces exclusively long-term depression in the majority of experiments, whereas single bursts ("single-sniff paradigm") can elicit both long-term potentiation and depression. Statistical analysis predicts that the mechanism underlying this bidirectional plasticity involves the proportional addition or removal of presynaptic release sites. Gamma stimulation with the same number of APs as in TBS was less efficient in inducing plasticity. Both TBS- and "single-sniff paradigm"-induced plasticity depend on NMDA receptor activation. Since the onset of plasticity is very rapid and requires little extra activity, we propose that these forms of plasticity might play a role already during an ongoing search for odor sources. Our results imply that components of both short-term and long-term olfactory memory may be encoded at this synapse.
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49
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Wienisch M, Murthy VN. Population imaging at subcellular resolution supports specific and local inhibition by granule cells in the olfactory bulb. Sci Rep 2016; 6:29308. [PMID: 27388949 PMCID: PMC4937346 DOI: 10.1038/srep29308] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 06/09/2016] [Indexed: 11/24/2022] Open
Abstract
Information processing in early sensory regions is modulated by a diverse range of inhibitory interneurons. We sought to elucidate the role of olfactory bulb interneurons called granule cells (GCs) in odor processing by imaging the activity of hundreds of these cells simultaneously in mice. Odor responses in GCs were temporally diverse and spatially disperse, with some degree of non-random, modular organization. The overall sparseness of activation of GCs was highly correlated with the extent of glomerular activation by odor stimuli. Increasing concentrations of single odorants led to proportionately larger population activity, but some individual GCs had non-monotonic relations to concentration due to local inhibitory interactions. Individual dendritic segments could sometimes respond independently to odors, revealing their capacity for compartmentalized signaling in vivo. Collectively, the response properties of GCs point to their role in specific and local processing, rather than global operations such as response normalization proposed for other interneurons.
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Affiliation(s)
- Martin Wienisch
- Center for Brain Science and Department of Molecular &Cellular Biology Harvard University, Cambridge 02138, MA, USA
| | - Venkatesh N Murthy
- Center for Brain Science and Department of Molecular &Cellular Biology Harvard University, Cambridge 02138, MA, USA
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50
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Thiebaud N, Llewellyn-Smith IJ, Gribble F, Reimann F, Trapp S, Fadool DA. The incretin hormone glucagon-like peptide 1 increases mitral cell excitability by decreasing conductance of a voltage-dependent potassium channel. J Physiol 2016; 594:2607-28. [PMID: 26931093 PMCID: PMC4865572 DOI: 10.1113/jp272322] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 02/25/2016] [Indexed: 02/06/2023] Open
Abstract
Key points The gut hormone called glucagon‐like peptide 1 (GLP‐1) is a strong moderator of energy homeostasis and communication between the peripheral organs and the brain. GLP‐1 signalling occurs in the brain; using a newly developed genetic reporter line of mice, we have discovered GLP‐synthesizing cells in the olfactory bulb. GLP‐1 increases the firing frequency of neurons (mitral cells) that encode olfactory information by decreasing activity of voltage‐dependent K channels (Kv1.3). Modifying GLP‐1 levels, either therapeutically or following the ingestion of food, could alter the excitability of neurons in the olfactory bulb in a nutrition or energy state‐dependent manner to influence olfactory detection or metabolic sensing. The results of the present study uncover a new function for an olfactory bulb neuron (deep short axon cells, Cajal cells) that could be capable of modifying mitral cell activity through the release of GLP‐1. This might be of relevance for the action of GLP‐1 mimetics now widely used in the treatment of diabetes.
Abstract The olfactory system is intricately linked with the endocrine system where it may serve as a detector of the internal metabolic state or energy homeostasis in addition to its classical function as a sensor of external olfactory information. The recent development of transgenic mGLU‐yellow fluorescent protein mice that express a genetic reporter under the control of the preproglucagon reporter suggested the presence of the gut hormone, glucagon‐like peptide (GLP‐1), in deep short axon cells (Cajal cells) of the olfactory bulb and its neuromodulatory effect on mitral cell (MC) first‐order neurons. A MC target for the peptide was determined using GLP‐1 receptor binding assays, immunocytochemistry for the receptor and injection of fluorescence‐labelled GLP‐1 analogue exendin‐4. Using patch clamp recording of olfactory bulb slices in the whole‐cell configuration, we report that GLP‐1 and its stable analogue exendin‐4 increase the action potential firing frequency of MCs by decreasing the interburst interval rather than modifying the action potential shape, train length or interspike interval. GLP‐1 decreases Kv1.3 channel contribution to outward currents in voltage clamp recordings as determined by pharmacological blockade of Kv1.3 or utilizing mice with Kv1.3 gene‐targeted deletion as a negative control. Because fluctuations in GLP‐1 concentrations monitored by the olfactory bulb can modify the firing frequency of MCs, olfactory coding could change depending upon nutritional or physiological state. As a regulator of neuronal activity, GLP‐1 or its analogue may comprise a new metabolic factor with a potential therapeutic target in the olfactory bulb (i.e. via intranasal delivery) for controlling an imbalance in energy homeostasis. The gut hormone called glucagon‐like peptide 1 (GLP‐1) is a strong moderator of energy homeostasis and communication between the peripheral organs and the brain. GLP‐1 signalling occurs in the brain; using a newly developed genetic reporter line of mice, we have discovered GLP‐synthesizing cells in the olfactory bulb. GLP‐1 increases the firing frequency of neurons (mitral cells) that encode olfactory information by decreasing activity of voltage‐dependent K channels (Kv1.3). Modifying GLP‐1 levels, either therapeutically or following the ingestion of food, could alter the excitability of neurons in the olfactory bulb in a nutrition or energy state‐dependent manner to influence olfactory detection or metabolic sensing. The results of the present study uncover a new function for an olfactory bulb neuron (deep short axon cells, Cajal cells) that could be capable of modifying mitral cell activity through the release of GLP‐1. This might be of relevance for the action of GLP‐1 mimetics now widely used in the treatment of diabetes.
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Affiliation(s)
- Nicolas Thiebaud
- The Florida State University, Department of Biological Science, Program in Neuroscience, Tallahassee, FL, USA
| | - Ida J Llewellyn-Smith
- Cardiovascular Medicine and Human Physiology, School of Medicine, Flinders University, Bedford Park, SA, Australia
| | - Fiona Gribble
- Cambridge Institute for Medical Research, Addenbrooke's Hospital, Cambridge, UK
| | - Frank Reimann
- Cambridge Institute for Medical Research, Addenbrooke's Hospital, Cambridge, UK
| | - Stefan Trapp
- Centre for Cardiovascular and Metabolic Neuroscience, Department of Neuroscience, Physiology, and Pharmacology, University College London, London, UK.,Department of Surgery and Cancer, Imperial College London, London, UK
| | - Debra Ann Fadool
- The Florida State University, Department of Biological Science, Program in Neuroscience, Tallahassee, FL, USA.,The Florida State University, Institute of Molecular Biophysics, Tallahassee, FL, USA
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