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Kebschull JM, Casoni F, Consalez GG, Goldowitz D, Hawkes R, Ruigrok TJH, Schilling K, Wingate R, Wu J, Yeung J, Uusisaari MY. Cerebellum Lecture: the Cerebellar Nuclei-Core of the Cerebellum. CEREBELLUM (LONDON, ENGLAND) 2024; 23:620-677. [PMID: 36781689 PMCID: PMC10951048 DOI: 10.1007/s12311-022-01506-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 12/10/2022] [Indexed: 02/15/2023]
Abstract
The cerebellum is a key player in many brain functions and a major topic of neuroscience research. However, the cerebellar nuclei (CN), the main output structures of the cerebellum, are often overlooked. This neglect is because research on the cerebellum typically focuses on the cortex and tends to treat the CN as relatively simple output nuclei conveying an inverted signal from the cerebellar cortex to the rest of the brain. In this review, by adopting a nucleocentric perspective we aim to rectify this impression. First, we describe CN anatomy and modularity and comprehensively integrate CN architecture with its highly organized but complex afferent and efferent connectivity. This is followed by a novel classification of the specific neuronal classes the CN comprise and speculate on the implications of CN structure and physiology for our understanding of adult cerebellar function. Based on this thorough review of the adult literature we provide a comprehensive overview of CN embryonic development and, by comparing cerebellar structures in various chordate clades, propose an interpretation of CN evolution. Despite their critical importance in cerebellar function, from a clinical perspective intriguingly few, if any, neurological disorders appear to primarily affect the CN. To highlight this curious anomaly, and encourage future nucleocentric interpretations, we build on our review to provide a brief overview of the various syndromes in which the CN are currently implicated. Finally, we summarize the specific perspectives that a nucleocentric view of the cerebellum brings, move major outstanding issues in CN biology to the limelight, and provide a roadmap to the key questions that need to be answered in order to create a comprehensive integrated model of CN structure, function, development, and evolution.
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Affiliation(s)
- Justus M Kebschull
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, 21205, USA.
| | - Filippo Casoni
- Division of Neuroscience, San Raffaele Scientific Institute, and San Raffaele University, Milan, Italy
| | - G Giacomo Consalez
- Division of Neuroscience, San Raffaele Scientific Institute, and San Raffaele University, Milan, Italy
| | - Daniel Goldowitz
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, Canada
| | - Richard Hawkes
- Department of Cell Biology & Anatomy and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, T2N 4N1, Canada
| | - Tom J H Ruigrok
- Department of Neuroscience, Erasmus MC, Rotterdam, the Netherlands
| | - Karl Schilling
- Department of Anatomy, Anatomy & Cell Biology, Rheinische Friedrich-Wilhelms-Universität, 53115, Bonn, Federal Republic of Germany
| | - Richard Wingate
- MRC Centre for Neurodevelopmental Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
| | - Joshua Wu
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, Canada
| | - Joanna Yeung
- Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, Canada
| | - Marylka Yoe Uusisaari
- Neuronal Rhythms in Movement Unit, Okinawa Institute of Science and Technology, 1919-1 Tancha, Onna-Son, Kunigami-Gun, Okinawa, 904-0495, Japan.
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2
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Schreurs BG, O'Dell DE, Wang D. The Role of Cerebellar Intrinsic Neuronal Excitability, Synaptic Plasticity, and Perineuronal Nets in Eyeblink Conditioning. BIOLOGY 2024; 13:200. [PMID: 38534469 DOI: 10.3390/biology13030200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 02/29/2024] [Accepted: 03/19/2024] [Indexed: 03/28/2024]
Abstract
Evidence is strong that, in addition to fine motor control, there is an important role for the cerebellum in cognition and emotion. The deep nuclei of the mammalian cerebellum also contain the highest density of perineural nets-mesh-like structures that surround neurons-in the brain, and it appears there may be a connection between these nets and cognitive processes, particularly learning and memory. Here, we review how the cerebellum is involved in eyeblink conditioning-a particularly well-understood form of learning and memory-and focus on the role of perineuronal nets in intrinsic membrane excitability and synaptic plasticity that underlie eyeblink conditioning. We explore the development and role of perineuronal nets and the in vivo and in vitro evidence that manipulations of the perineuronal net in the deep cerebellar nuclei affect eyeblink conditioning. Together, these findings provide evidence of an important role for perineuronal net in learning and memory.
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Affiliation(s)
- Bernard G Schreurs
- Department of Neuroscience, West Virginia University, Morgantown, WV 26505, USA
| | - Deidre E O'Dell
- Department of Biology, Earth and Environmental Sciences, Pennsylvania Western (PennWest) University, California, PA 15419, USA
| | - Desheng Wang
- Department of Neuroscience, West Virginia University, Morgantown, WV 26505, USA
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3
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Kang S, Jun S, Baek SJ, Park H, Yamamoto Y, Tanaka-Yamamoto K. Recent Advances in the Understanding of Specific Efferent Pathways Emerging From the Cerebellum. Front Neuroanat 2021; 15:759948. [PMID: 34975418 PMCID: PMC8716603 DOI: 10.3389/fnana.2021.759948] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 11/15/2021] [Indexed: 11/13/2022] Open
Abstract
The cerebellum has a long history in terms of research on its network structures and motor functions, yet our understanding of them has further advanced in recent years owing to technical developments, such as viral tracers, optogenetic and chemogenetic manipulation, and single cell gene expression analyses. Specifically, it is now widely accepted that the cerebellum is also involved in non-motor functions, such as cognitive and psychological functions, mainly from studies that have clarified neuronal pathways from the cerebellum to other brain regions that are relevant to these functions. The techniques to manipulate specific neuronal pathways were effectively utilized to demonstrate the involvement of the cerebellum and its pathways in specific brain functions, without altering motor activity. In particular, the cerebellar efferent pathways that have recently gained attention are not only monosynaptic connections to other brain regions, including the periaqueductal gray and ventral tegmental area, but also polysynaptic connections to other brain regions, including the non-primary motor cortex and hippocampus. Besides these efferent pathways associated with non-motor functions, recent studies using sophisticated experimental techniques further characterized the historically studied efferent pathways that are primarily associated with motor functions. Nevertheless, to our knowledge, there are no articles that comprehensively describe various cerebellar efferent pathways, although there are many interesting review articles focusing on specific functions or pathways. Here, we summarize the recent findings on neuronal networks projecting from the cerebellum to several brain regions. We also introduce various techniques that have enabled us to advance our understanding of the cerebellar efferent pathways, and further discuss possible directions for future research regarding these efferent pathways and their functions.
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Affiliation(s)
- Seulgi Kang
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, South Korea
- Division of Bio-Medical Science and Technology, KIST School, University of Science and Technology (UST), Seoul, South Korea
| | - Soyoung Jun
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, South Korea
- Division of Bio-Medical Science and Technology, KIST School, University of Science and Technology (UST), Seoul, South Korea
| | - Soo Ji Baek
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, South Korea
- Division of Bio-Medical Science and Technology, KIST School, University of Science and Technology (UST), Seoul, South Korea
| | - Heeyoun Park
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, South Korea
| | - Yukio Yamamoto
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, South Korea
| | - Keiko Tanaka-Yamamoto
- Brain Science Institute, Korea Institute of Science and Technology (KIST), Seoul, South Korea
- Division of Bio-Medical Science and Technology, KIST School, University of Science and Technology (UST), Seoul, South Korea
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4
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Beekhof GC, Gornati SV, Canto CB, Libster AM, Schonewille M, De Zeeuw CI, Hoebeek FE. Activity of Cerebellar Nuclei Neurons Correlates with ZebrinII Identity of Their Purkinje Cell Afferents. Cells 2021; 10:2686. [PMID: 34685666 PMCID: PMC8534335 DOI: 10.3390/cells10102686] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Revised: 09/24/2021] [Accepted: 09/28/2021] [Indexed: 11/17/2022] Open
Abstract
Purkinje cells (PCs) in the cerebellar cortex can be divided into at least two main subpopulations: one subpopulation that prominently expresses ZebrinII (Z+), and shows a relatively low simple spike firing rate, and another that hardly expresses ZebrinII (Z-) and shows higher baseline firing rates. Likewise, the complex spike responses of PCs, which are evoked by climbing fiber inputs and thus reflect the activity of the inferior olive (IO), show the same dichotomy. However, it is not known whether the target neurons of PCs in the cerebellar nuclei (CN) maintain this bimodal distribution. Electrophysiological recordings in awake adult mice show that the rate of action potential firing of CN neurons that receive input from Z+ PCs was consistently lower than that of CN neurons innervated by Z- PCs. Similar in vivo recordings in juvenile and adolescent mice indicated that the firing frequency of CN neurons correlates to the ZebrinII identity of the PC afferents in adult, but not postnatal stages. Finally, the spontaneous action potential firing pattern of adult CN neurons recorded in vitro revealed no significant differences in intrinsic pacemaking activity between ZebrinII identities. Our findings indicate that all three main components of the olivocerebellar loop, i.e., PCs, IO neurons and CN neurons, operate at a higher rate in the Z- modules.
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Affiliation(s)
- Gerrit C. Beekhof
- Department of Neuroscience, Erasmus Medical Center, 3015 AA Rotterdam, The Netherlands; (G.C.B.); (S.V.G.)
- Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences (KNAW), 1105 BA Amsterdam, The Netherlands;
| | - Simona V. Gornati
- Department of Neuroscience, Erasmus Medical Center, 3015 AA Rotterdam, The Netherlands; (G.C.B.); (S.V.G.)
| | - Cathrin B. Canto
- Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences (KNAW), 1105 BA Amsterdam, The Netherlands;
| | - Avraham M. Libster
- Edmond & Lily Safra Center for Brain Sciences (ELSC), Department of Neurobiology, Institute of Life Sciences, The Hebrew University, Jerusalem 91904, Israel;
| | - Martijn Schonewille
- Department of Neuroscience, Erasmus Medical Center, 3015 AA Rotterdam, The Netherlands; (G.C.B.); (S.V.G.)
| | - Chris I. De Zeeuw
- Department of Neuroscience, Erasmus Medical Center, 3015 AA Rotterdam, The Netherlands; (G.C.B.); (S.V.G.)
- Netherlands Institute for Neuroscience, Royal Academy of Arts and Sciences (KNAW), 1105 BA Amsterdam, The Netherlands;
| | - Freek E. Hoebeek
- Department of Neuroscience, Erasmus Medical Center, 3015 AA Rotterdam, The Netherlands; (G.C.B.); (S.V.G.)
- Department for Developmental Origins of Disease, Wilhelmina Children’s Hospital, Brain Center, University Medical Center Utrecht, 3584 EA Utrecht, The Netherlands
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5
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Daou A, Margoliash D. Intrinsic plasticity and birdsong learning. Neurobiol Learn Mem 2021; 180:107407. [PMID: 33631346 DOI: 10.1016/j.nlm.2021.107407] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 10/28/2020] [Accepted: 02/11/2021] [Indexed: 10/22/2022]
Abstract
Although information processing and storage in the brain is thought to be primarily orchestrated by synaptic plasticity, other neural mechanisms such as intrinsic plasticity are available. While a number of recent studies have described the plasticity of intrinsic excitability in several types of neurons, the significance of non-synaptic mechanisms in memory and learning remains elusive. After reviewing plasticity of intrinsic excitation in relation to learning and homeostatic mechanisms, we focus on the intrinsic properties of a class of basal-ganglia projecting song system neurons in zebra finch, how these related to each bird's unique learned song, how these properties change over development, and how they are maintained dynamically to rapidly change in response to auditory feedback perturbations. We place these results in the broader theme of learning and changes in intrinsic properties, emphasizing the computational implications of this form of plasticity, which are distinct from synaptic plasticity. The results suggest that exploring reciprocal interactions between intrinsic and network properties will be a fruitful avenue for understanding mechanisms of birdsong learning.
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Affiliation(s)
- Arij Daou
- University of Chicago, United States
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6
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O'Dell DE, Schreurs BG, Smith-Bell C, Wang D. Disruption of rat deep cerebellar perineuronal net alters eyeblink conditioning and neuronal electrophysiology. Neurobiol Learn Mem 2021; 177:107358. [PMID: 33285318 PMCID: PMC8279724 DOI: 10.1016/j.nlm.2020.107358] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 11/04/2020] [Accepted: 11/16/2020] [Indexed: 01/26/2023]
Abstract
The perineuronal net (PNN) is a specialized type of extracellular matrix found in the central nervous system. The PNN forms on fast spiking neurons during postnatal development but the ontogeny of PNN development has yet to be elucidated. By studying the development and prevalence of the PNN in the juvenile and adult rat brain, we may be able to understand the PNN's role in development and learning and memory. We show that the PNN is fully developed in the deep cerebellar nuclei (DCN) of rats by P18. By using enzymatic digestion of the PNN with chondroitinase ABC (ChABC), we are able to study how digestion of the PNN affects cerebellar-dependent eyeblink conditioning in vivo and perform electrophysiological recordings from DCN neurons in vitro. In vivo degradation of the PNN resulted in significant differences in eyeblink conditioning amplitude and area. Female animals in the vehicle group demonstrated higher levels of conditioning as well as significantly higher post-probe conditioned responses compared to males in that group, differences not present in the ChABC group. In vitro, we found that DCN neurons with a disrupted PNN following exposure to ChABC had altered membrane properties, fewer rebound spikes, and decreased intrinsic excitability. Together, this study further elucidates the role of the PNN in cerebellar learning in the DCN and is the first to demonstrate PNN degradation may erase sex differences in delay conditioning.
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Affiliation(s)
- Deidre E O'Dell
- Department of Neuroscience, Rockefeller Neuroscience Institute, WVU, 33 Medical Center Dr, Morgantown, WV 26505, United States.
| | - Bernard G Schreurs
- Department of Neuroscience, Rockefeller Neuroscience Institute, WVU, 33 Medical Center Dr, Morgantown, WV 26505, United States
| | - Carrie Smith-Bell
- Department of Neuroscience, Rockefeller Neuroscience Institute, WVU, 33 Medical Center Dr, Morgantown, WV 26505, United States
| | - Desheng Wang
- Department of Neuroscience, Rockefeller Neuroscience Institute, WVU, 33 Medical Center Dr, Morgantown, WV 26505, United States
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7
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Thanawalla AR, Chen AI, Azim E. The Cerebellar Nuclei and Dexterous Limb Movements. Neuroscience 2020; 450:168-183. [PMID: 32652173 PMCID: PMC7688491 DOI: 10.1016/j.neuroscience.2020.06.046] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 06/03/2020] [Accepted: 06/30/2020] [Indexed: 01/21/2023]
Abstract
Dexterous forelimb movements like reaching, grasping, and manipulating objects are fundamental building blocks of the mammalian motor repertoire. These behaviors are essential to everyday activities, and their elaboration underlies incredible accomplishments by human beings in art and sport. Moreover, the susceptibility of these behaviors to damage and disease of the nervous system can lead to debilitating deficits, highlighting a need for a better understanding of function and dysfunction in sensorimotor control. The cerebellum is central to coordinating limb movements, as defined in large part by Joseph Babinski and Gordon Holmes describing motor impairment in patients with cerebellar lesions over 100 years ago (Babinski, 1902; Holmes, 1917), and supported by many important human and animal studies that have been conducted since. Here, with a focus on output pathways of the cerebellar nuclei across mammalian species, we describe forelimb movement deficits observed when cerebellar circuits are perturbed, the mechanisms through which these circuits influence motor output, and key challenges in defining how the cerebellum refines limb movement.
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Affiliation(s)
- Ayesha R Thanawalla
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA
| | - Albert I Chen
- Nanyang Technological University (NTU), School of Biological Sciences, 11 Mandalay Road, Singapore 308232, Singapore; A*STAR, Institute of Molecular and Cell Biology, 61 Biopolis Drive, Singapore 308232, Singapore.
| | - Eiman Azim
- Molecular Neurobiology Laboratory, Salk Institute for Biological Studies, 10010 N. Torrey Pines Road, La Jolla, CA 92037, USA.
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8
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Activity-dependent compensation of cell size is vulnerable to targeted deletion of ion channels. Sci Rep 2020; 10:15989. [PMID: 32994529 PMCID: PMC7524806 DOI: 10.1038/s41598-020-72977-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Accepted: 08/25/2020] [Indexed: 01/13/2023] Open
Abstract
In many species, excitable cells preserve their physiological properties despite significant variation in physical size across time and in a population. For example, neurons in crustacean central pattern generators generate similar firing patterns despite several-fold increases in size between juveniles and adults. This presents a biophysical problem because the electrical properties of cells are highly sensitive to membrane area and channel density. It is not known whether specific mechanisms exist to sense membrane area and adjust channel expression to keep a consistent channel density, or whether regulation mechanisms that sense activity alone are capable of compensating cell size. We show that destabilising effects of growth can be specifically compensated by feedback mechanism that senses average calcium influx and jointly regulate multiple conductances. However, we further show that this class of growth-compensating regulation schemes is necessarily sensitive to perturbations that alter the expression of subsets of ion channel types. Targeted perturbations of specific ion channels can trigger a pathological response of the regulation mechanism and a failure of homeostasis. Our findings suggest that physiological regulation mechanisms that confer robustness to growth may be specifically vulnerable to deletions or mutations that affect subsets of ion channels.
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9
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Kim E, Jeon S, An HK, Kianpour M, Yu SW, Kim JY, Rah JC, Choi H. A magnetically actuated microrobot for targeted neural cell delivery and selective connection of neural networks. SCIENCE ADVANCES 2020; 6:eabb5696. [PMID: 32978164 PMCID: PMC7518876 DOI: 10.1126/sciadv.abb5696] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2020] [Accepted: 08/10/2020] [Indexed: 05/02/2023]
Abstract
There has been a great deal of interest in the development of technologies for actively manipulating neural networks in vitro, providing natural but simplified environments in a highly reproducible manner in which to study brain function and related diseases. Platforms for these in vitro neural networks require precise and selective neural connections at the target location, with minimal external influences, and measurement of neural activity to determine how neurons communicate. Here, we report a neuron-loaded microrobot for selective connection of neural networks via precise delivery to a gap between two neural clusters by an external magnetic field. In addition, the extracellular action potential was propagated from one cluster to the other through the neurons on the microrobot. The proposed technique shows the potential for use in experiments to understand how neurons communicate in the neural network by actively connecting neural clusters.
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Affiliation(s)
- Eunhee Kim
- Department of Robotics Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, South Korea
- DGIST-ETH Microrobot Research Center, DGIST, Daegu 42988, South Korea
| | - Sungwoong Jeon
- Department of Robotics Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, South Korea
- DGIST-ETH Microrobot Research Center, DGIST, Daegu 42988, South Korea
| | - Hyun-Kyu An
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, South Korea
| | | | - Seong-Woon Yu
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, South Korea
| | - Jin-Young Kim
- Department of Robotics Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, South Korea.
- DGIST-ETH Microrobot Research Center, DGIST, Daegu 42988, South Korea
| | - Jong-Cheol Rah
- Department of Brain and Cognitive Sciences, DGIST, Daegu 42988, South Korea
- Korea Brain Research Institute, Daegu 42988, South Korea
| | - Hongsoo Choi
- Department of Robotics Engineering, Daegu Gyeongbuk Institute of Science and Technology (DGIST), Daegu 42988, South Korea.
- DGIST-ETH Microrobot Research Center, DGIST, Daegu 42988, South Korea
- Robotics Research Center, DGIST, Daegu 42988, South Korea
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10
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Zhou P, Liao G, Zhong Q, Wen Q, Gao G, Zhang C. Muscarinic Acetylcholine Receptor-2 in the Cerebellar Fastigial Nucleus is Involved in Acetylcholine-Mediated Blood Pressure Regulation in Rats. NEUROCHEM J+ 2019. [DOI: 10.1134/s1819712419020168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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11
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Casali S, Marenzi E, Medini C, Casellato C, D'Angelo E. Reconstruction and Simulation of a Scaffold Model of the Cerebellar Network. Front Neuroinform 2019; 13:37. [PMID: 31156416 PMCID: PMC6530631 DOI: 10.3389/fninf.2019.00037] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 04/29/2019] [Indexed: 02/05/2023] Open
Abstract
Reconstructing neuronal microcircuits through computational models is fundamental to simulate local neuronal dynamics. Here a scaffold model of the cerebellum has been developed in order to flexibly place neurons in space, connect them synaptically, and endow neurons and synapses with biologically-grounded mechanisms. The scaffold model can keep neuronal morphology separated from network connectivity, which can in turn be obtained from convergence/divergence ratios and axonal/dendritic field 3D geometries. We first tested the scaffold on the cerebellar microcircuit, which presents a challenging 3D organization, at the same time providing appropriate datasets to validate emerging network behaviors. The scaffold was designed to integrate the cerebellar cortex with deep cerebellar nuclei (DCN), including different neuronal types: Golgi cells, granule cells, Purkinje cells, stellate cells, basket cells, and DCN principal cells. Mossy fiber inputs were conveyed through the glomeruli. An anisotropic volume (0.077 mm3) of mouse cerebellum was reconstructed, in which point-neuron models were tuned toward the specific discharge properties of neurons and were connected by exponentially decaying excitatory and inhibitory synapses. Simulations using both pyNEST and pyNEURON showed the emergence of organized spatio-temporal patterns of neuronal activity similar to those revealed experimentally in response to background noise and burst stimulation of mossy fiber bundles. Different configurations of granular and molecular layer connectivity consistently modified neuronal activation patterns, revealing the importance of structural constraints for cerebellar network functioning. The scaffold provided thus an effective workflow accounting for the complex architecture of the cerebellar network. In principle, the scaffold can incorporate cellular mechanisms at multiple levels of detail and be tuned to test different structural and functional hypotheses. A future implementation using detailed 3D multi-compartment neuron models and dynamic synapses will be needed to investigate the impact of single neuron properties on network computation.
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Affiliation(s)
- Stefano Casali
- Neurophysiology Unit, Neurocomputational Laboratory, Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Elisa Marenzi
- Neurophysiology Unit, Neurocomputational Laboratory, Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Chaitanya Medini
- Neurophysiology Unit, Neurocomputational Laboratory, Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Claudia Casellato
- Neurophysiology Unit, Neurocomputational Laboratory, Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
| | - Egidio D'Angelo
- Neurophysiology Unit, Neurocomputational Laboratory, Department of Brain and Behavioral Sciences, University of Pavia, Pavia, Italy
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12
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Pickford J, Apps R, Bashir ZI. Muscarinic Receptor Modulation of the Cerebellar Interpositus Nucleus In Vitro. Neurochem Res 2019; 44:627-635. [PMID: 30117095 PMCID: PMC6420442 DOI: 10.1007/s11064-018-2613-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 08/09/2018] [Accepted: 08/11/2018] [Indexed: 11/25/2022]
Abstract
How the cerebellum carries out its functions is not clear, even for its established roles in motor control. In particular, little is known about how the cerebellar nuclei (CN) integrate their synaptic and neuromodulatory inputs to generate cerebellar output. CN neurons receive inhibitory inputs from Purkinje cells, excitatory inputs from mossy fibre and climbing fibre collaterals, as well as a variety of neuromodulatory inputs, including cholinergic inputs. In this study we tested how activation of acetylcholine receptors modulated firing rate, intrinsic properties and synaptic transmission in the CN. Using in vitro whole-cell patch clamp recordings from neurons in the interpositus nucleus, the acetylcholine receptor agonist carbachol was shown to induce a short-term increase in firing rate, increase holding current and decrease input resistance of interpositus CN neurons. Carbachol also induced long-term depression of evoked inhibitory postsynaptic currents and a short-term depression of evoked excitatory postsynaptic currents. All effects were shown to be dependent upon muscarinic acetylcholine receptor activation. Overall, the present study has identified muscarinic receptor activation as a modulator of CN activity.
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Affiliation(s)
- J Pickford
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, UK.
| | - R Apps
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, UK
| | - Z I Bashir
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, UK
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13
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Sox14 Is Required for a Specific Subset of Cerebello-Olivary Projections. J Neurosci 2018; 38:9539-9550. [PMID: 30242051 DOI: 10.1523/jneurosci.1456-18.2018] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Revised: 09/02/2018] [Accepted: 09/04/2018] [Indexed: 02/02/2023] Open
Abstract
We identify Sox14 as an exclusive marker of inhibitory projection neurons in the lateral and interposed, but not the medial, cerebellar nuclei. Sox14+ neurons make up ∼80% of Gad1+ neurons in these nuclei and are indistinguishable by soma size from other inhibitory neurons. All Sox14+ neurons of the lateral and interposed cerebellar nuclei are generated at approximately E10/10.5 and extend long-range, predominantly contralateral projections to the inferior olive. A small Sox14+ population in the adjacent vestibular nucleus "Y" sends an ipsilateral projection to the oculomotor nucleus. Cerebellar Sox14+ and glutamatergic projection neurons assemble in non-overlapping populations at the nuclear transition zone, and their integration into a coherent nucleus depends on Sox14 function. Targeted ablation of Sox14+ cells by conditional viral expression of diphtheria toxin leads to significantly impaired motor learning. Contrary to expectations, associative learning is unaffected by unilateral Sox14+ neuron elimination in the interposed and lateral nuclei.SIGNIFICANCE STATEMENT The cerebellar nuclei are central to cerebellar function, yet how they modulate and process cerebellar inputs and outputs is still primarily unknown. Our study gives a direct insight into how nucleo-olivary projection neurons are generated, their projections, and their function in an intact behaving mouse. These neurons play a critical conceptual role in all models of cerebellar function, and this study represents the first specific analysis of their molecular identity and function and offers a powerful model for future investigation of cerebellar function in motor control and learning.
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14
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Changes in membrane properties of rat deep cerebellar nuclear projection neurons during acquisition of eyeblink conditioning. Proc Natl Acad Sci U S A 2018; 115:E9419-E9428. [PMID: 30154170 DOI: 10.1073/pnas.1808539115] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Previous studies have shown changes in membrane properties of neurons in rat deep cerebellar nuclei (DCN) as a function of development, but due to technical difficulties in obtaining viable DCN slices from adult animals, it remains unclear whether there are learning-related alterations in the membrane properties of DCN neurons in adult rats. This study was designed to record from identified DCN cells in cerebellar slices from postnatal day 25-26 (P25-26) rats that had a relatively mature sensory nervous system and were able to acquire learning as a result of tone-shock eyeblink conditioning (EBC) and to document resulting changes in electrophysiological properties. After electromyographic electrode implantation at P21 and inoculation with a fluorescent pseudorabies virus (PRV-152) at P22-23, rats received either four sessions of paired delay EBC or unpaired stimulus presentations with a tone conditioned stimulus and a shock unconditioned stimulus or sat in the training chamber without stimulus presentations. Compared with rats given unpaired stimuli or no stimulus presentations, rats given paired EBC showed an increase in conditioned responses across sessions. Whole-cell recordings of both fluorescent and nonfluorescent DCN projection neurons showed that delay EBC induced significant changes in membrane properties of evoked DCN action potentials including a reduced after-hyperpolarization amplitude and shortened latency. Similar findings were obtained in hyperpolarization-induced rebound spikes of DCN neurons. In sum, delay EBC produced significant changes in the membrane properties of juvenile rat DCN projection neurons. These learning-specific changes in DCN excitability have not previously been reported in any species or task.
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15
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The transgenic mouse line Igsf9- eGFP allows targeted stimulation of inferior olive efferents. J Neurosci Methods 2018; 296:84-92. [DOI: 10.1016/j.jneumeth.2017.12.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2017] [Accepted: 12/26/2017] [Indexed: 11/20/2022]
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16
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Wang Y, Chen ZP, Zhuang QX, Zhang XY, Li HZ, Wang JJ, Zhu JN. Role of Corticotropin-Releasing Factor in Cerebellar Motor Control and Ataxia. Curr Biol 2017; 27:2661-2669.e5. [DOI: 10.1016/j.cub.2017.07.035] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 07/11/2017] [Accepted: 07/13/2017] [Indexed: 02/02/2023]
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17
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Yang Z, Chen N, Ge R, Qian H, Wang JH. Functional compatibility between Purkinje cell axon branches and their target neurons in the cerebellum. Oncotarget 2017; 8:72424-72437. [PMID: 29069799 PMCID: PMC5641142 DOI: 10.18632/oncotarget.19770] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 06/28/2017] [Indexed: 01/10/2023] Open
Abstract
A neuron sprouts an axon, and its branches to innervate many target neurons that are divergent in their functions. In order to efficiently regulate the diversified cells, the axon branches should differentiate functionally to be compatible with their target neurons, i.e., a function compatibility between presynaptic and postsynaptic partners. We have examined this hypothesis by using electrophysiological method in the cerebellum, in which the main axon of Purkinje cell projected to deep nucleus cells and the recurrent axons innervated the adjacent Purkinje cells. The fidelity of spike propagation is superior in the recurrent branches than the main axon. The capabilities of encoding spikes and processing GABAergic inputs are advanced in Purkinje cells versus deep nucleus cells. The functional differences among Purkinje's axonal branches and their postsynaptic neurons are preset by the variable dynamics of their voltage-gated sodium channels. In addition, activity strengths between presynaptic and postsynaptic partners are proportionally correlated, i.e., active axonal branches innervate active target neurons, or vice versa. The physiological impact of the functional compatibility is to make the neurons in their circuits to be activated appropriately. In conclusion, each cerebellar Purkinje cell sprouts the differentiated axon branches to be compatible with the diversified target cells in their functions, in order to construct the homeostatic and efficient units for their coordinated activity in neural circuits.
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Affiliation(s)
- Zhilai Yang
- Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,Department of Anesthesiology, The First Affiliated Hospital of Anhui Medical University, Hefei 230022, China
| | - Na Chen
- Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Rongjing Ge
- Department of Physiology, Bengbu Medical College, Bengbu 233000, China
| | - Hao Qian
- Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Jin-Hui Wang
- Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.,College of Life Science, University of Chinese Academy of Sciences, Beijing 100049, China.,Qingdao University, School of Pharmacy, Shandong 266021, China.,Department of Physiology, Bengbu Medical College, Bengbu 233000, China
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18
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Matsuno H, Kudoh M, Watakabe A, Yamamori T, Shigemoto R, Nagao S. Distribution and Structure of Synapses on Medial Vestibular Nuclear Neurons Targeted by Cerebellar Flocculus Purkinje Cells and Vestibular Nerve in Mice: Light and Electron Microscopy Studies. PLoS One 2016; 11:e0164037. [PMID: 27711146 PMCID: PMC5053601 DOI: 10.1371/journal.pone.0164037] [Citation(s) in RCA: 16] [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: 05/03/2016] [Accepted: 09/19/2016] [Indexed: 01/28/2023] Open
Abstract
Adaptations of vestibulo-ocular and optokinetic response eye movements have been studied as an experimental model of cerebellum-dependent motor learning. Several previous physiological and pharmacological studies have consistently suggested that the cerebellar flocculus (FL) Purkinje cells (P-cells) and the medial vestibular nucleus (MVN) neurons targeted by FL (FL-targeted MVN neurons) may respectively maintain the memory traces of short- and long-term adaptation. To study the basic structures of the FL-MVN synapses by light microscopy (LM) and electron microscopy (EM), we injected green florescence protein (GFP)-expressing lentivirus into FL to anterogradely label the FL P-cell axons in C57BL/6J mice. The FL P-cell axonal boutons were distributed in the magnocellular MVN and in the border region of parvocellular MVN and prepositus hypoglossi (PrH). In the magnocellular MVN, the FL-P cell axons mainly terminated on somata and proximal dendrites. On the other hand, in the parvocellular MVN/PrH, the FL P-cell axonal synaptic boutons mainly terminated on the relatively small-diameter (< 1 μm) distal dendrites of MVN neurons, forming symmetrical synapses. The majority of such parvocellular MVN/PrH neurons were determined to be glutamatergic by immunocytochemistry and in-situ hybridization of GFP expressing transgenic mice. To further examine the spatial relationship between the synapses of FL P-cells and those of vestibular nerve on the neurons of the parvocellular MVN/PrH, we added injections of biotinylated dextran amine into the semicircular canal and anterogradely labeled vestibular nerve axons in some mice. The MVN dendrites receiving the FL P-cell axonal synaptic boutons often closely apposed vestibular nerve synaptic boutons in both LM and EM studies. Such a partial overlap of synaptic boutons of FL P-cell axons with those of vestibular nerve axons in the distal dendrites of MVN neurons suggests that inhibitory synapses of FL P-cells may influence the function of neighboring excitatory synapses of vestibular nerve in the parvocellular MVN/PrH neurons.
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Affiliation(s)
- Hitomi Matsuno
- Laboratory for Motor Learning Control, Riken Brain Science Institute, Hirosawa 2-1, Wako, Saitama, 351-0198, Japan
- * E-mail: (HM); (SN)
| | - Moeko Kudoh
- Laboratory for Motor Learning Control, Riken Brain Science Institute, Hirosawa 2-1, Wako, Saitama, 351-0198, Japan
| | - Akiya Watakabe
- Laboratory for Molecular Analysis of Higher Brain Function, RIKEN Brain Science Institute, Hirosawa 2-1, Wako, Saitama, 351-0198, Japan
| | - Tetsuo Yamamori
- Laboratory for Molecular Analysis of Higher Brain Function, RIKEN Brain Science Institute, Hirosawa 2-1, Wako, Saitama, 351-0198, Japan
| | - Ryuichi Shigemoto
- Division of Cerebral Structure, National Institute for Physiological Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan
| | - Soichi Nagao
- Laboratory for Motor Learning Control, Riken Brain Science Institute, Hirosawa 2-1, Wako, Saitama, 351-0198, Japan
- * E-mail: (HM); (SN)
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19
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Gao Z, Proietti-Onori M, Lin Z, Ten Brinke MM, Boele HJ, Potters JW, Ruigrok TJH, Hoebeek FE, De Zeeuw CI. Excitatory Cerebellar Nucleocortical Circuit Provides Internal Amplification during Associative Conditioning. Neuron 2016; 89:645-57. [PMID: 26844836 PMCID: PMC4742536 DOI: 10.1016/j.neuron.2016.01.008] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2015] [Revised: 11/11/2015] [Accepted: 12/20/2015] [Indexed: 11/21/2022]
Abstract
Closed-loop circuitries between cortical and subcortical regions can facilitate precision of output patterns, but the role of such networks in the cerebellum remains to be elucidated. Here, we characterize the role of internal feedback from the cerebellar nuclei to the cerebellar cortex in classical eyeblink conditioning. We find that excitatory output neurons in the interposed nucleus provide efference-copy signals via mossy fibers to the cerebellar cortical zones that belong to the same module, triggering monosynaptic responses in granule and Golgi cells and indirectly inhibiting Purkinje cells. Upon conditioning, the local density of nucleocortical mossy fiber terminals significantly increases. Optogenetic activation and inhibition of nucleocortical fibers in conditioned animals increases and decreases the amplitude of learned eyeblink responses, respectively. Our data show that the excitatory nucleocortical closed-loop circuitry of the cerebellum relays a corollary discharge of premotor signals and suggests an amplifying role of this circuitry in controlling associative motor learning. Cerebellar nuclei provide modular corollary discharge to the cerebellar cortex Nucleocortical afferents have unique molecular and ultrastructural features Eyeblink conditioning induces structural plasticity of nucleocortical mossy fibers Nucleocortical afferents amplify the amplitude of conditioned eyeblink responses
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Affiliation(s)
- Zhenyu Gao
- Department of Neuroscience, Erasmus MC, 3015 CN Rotterdam, the Netherlands.
| | | | - Zhanmin Lin
- Department of Neuroscience, Erasmus MC, 3015 CN Rotterdam, the Netherlands
| | | | - Henk-Jan Boele
- Department of Neuroscience, Erasmus MC, 3015 CN Rotterdam, the Netherlands
| | - Jan-Willem Potters
- Department of Neuroscience, Erasmus MC, 3015 CN Rotterdam, the Netherlands
| | - Tom J H Ruigrok
- Department of Neuroscience, Erasmus MC, 3015 CN Rotterdam, the Netherlands
| | - Freek E Hoebeek
- Department of Neuroscience, Erasmus MC, 3015 CN Rotterdam, the Netherlands
| | - Chris I De Zeeuw
- Department of Neuroscience, Erasmus MC, 3015 CN Rotterdam, the Netherlands; Netherlands Institute for Neuroscience, Royal Dutch Academy of Arts & Sciences (KNAW), 1105 BA Amsterdam, the Netherlands.
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20
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Dykstra S, Engbers JDT, Bartoletti TM, Turner RW. Determinants of rebound burst responses in rat cerebellar nuclear neurons to physiological stimuli. J Physiol 2016; 594:985-1003. [PMID: 26662168 DOI: 10.1113/jp271894] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 12/05/2015] [Indexed: 01/28/2023] Open
Abstract
KEY POINTS Cerebellar Purkinje cells project GABAergic inhibitory input to neurons of the deep cerebellar nuclei (DCN) that generate a rebound increase in firing, but the specific patterns of input that might elicit a rebound response have not been established. We used recordings of Purkinje cell firing obtained during perioral whisker stimulation in vivo to create a physiological stimulus template to activate Purkinje cell afferents in vitro. DCN cell bursts were evoked by the stimulus pattern but not in relation to the perioral whisker stimulus, complex spikes or regular patterns within the Purkinje cell record. Reverse correlation revealed that bursts were triggered by an elevation-pause pattern of Purkinje cell firing, with pause duration a key factor in burst generation. Our data identify for the first time a physiological pattern of Purkinje cell input that can be encoded by the generation of rebound bursts in DCN cells. ABSTRACT The end result of signal processing in cerebellar cortex is encoded in the output of Purkinje cells that project inhibitory input to deep cerebellar nuclear (DCN) neurons. DCN cells can respond to a period of inhibition in vitro with a rebound burst of firing, yet the optimal physiological pattern of Purkinje cell input that might evoke a rebound burst is unknown. The current study used spike trains recorded from rat Purkinje cells in response to perioral stimuli in vivo to create a physiological pattern to stimulate Purkinje cell axons in vitro. The perioral stimulus-evoked Purkinje cell firing pattern proved to be virtually ineffective in evoking a rebound burst despite the ability to reliably evoke rebounds using a traditional brief 100 Hz stimulus. Similarly, neither complex spike firing nor Purkinje cell patterns identified by CV2 analysis were reliably associated with rebound bursts. Reverse correlation revealed that the optimal Purkinje cell input to evoke a rebound burst was a sequential increase in mean firing rate of at least 30 Hz above baseline over 250 ms followed by a reduction of 40-60 Hz below baseline for up to 500 ms. The most important factor was the duration of a pause in Purkinje cell firing that allowed DCN cells to recover from a state of net inhibitory influence. These data indicate that physiological patterns of Purkinje cell firing can elicit rebound bursts in DCN cells in vitro, with pauses in Purkinje cell firing rate acting as a key stimulus for DCN cell rebound responses.
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Affiliation(s)
- Steven Dykstra
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada, T2N 4N1
| | - Jordan D T Engbers
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada, T2N 4N1
| | - Theodore M Bartoletti
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada, T2N 4N1
| | - Ray W Turner
- Department of Cell Biology and Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta, Canada, T2N 4N1
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21
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Zhang J, Zhuang QX, Li B, Wu GY, Yung WH, Zhu JN, Wang JJ. Selective Modulation of Histaminergic Inputs on Projection Neurons of Cerebellum Rapidly Promotes Motor Coordination via HCN Channels. Mol Neurobiol 2015; 53:1386-1401. [PMID: 25633097 DOI: 10.1007/s12035-015-9096-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2014] [Accepted: 01/12/2015] [Indexed: 12/24/2022]
Abstract
Insights into function of central histaminergic system, a general modulator originating from the hypothalamus for whole brain activity, in motor control are critical for understanding the mechanism underlying somatic-nonsomatic integration. Here, we show a novel selective role of histamine in the cerebellar nuclei, the final integrative center and output of the cerebellum. Histamine depolarizes projection neurons but not interneurons in the cerebellar nuclei via the hyperpolarization-activated cyclic nucleotide-gated (HCN) channels coupled to histamine H2 receptors, which are exclusively expressed on glutamatergic and glycinergic projection neurons. Furthermore, blockage of HCN channels to block endogenous histaminergic afferent inputs in the cerebellar nuclei significantly attenuates motor balance and coordination. Therefore, through directly and quickly modulation on projection neurons but not interneurons in the cerebellar nuclei, central histaminergic system may act as a critical biasing force to not only promptly regulate ongoing movement but also realize a rapid integration of somatic and nonsomatic response.
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Affiliation(s)
- Jun Zhang
- State Key Laboratory of Pharmaceutical Biotechnology and Department of Biological Science and Technology, School of Life Sciences, Nanjing University, Mailbox 426, 22 Hankou Road, Nanjing, 210093, China.,Department of Physiology, Third Military Medical University, Chongqing, 400038, China
| | - Qian-Xing Zhuang
- State Key Laboratory of Pharmaceutical Biotechnology and Department of Biological Science and Technology, School of Life Sciences, Nanjing University, Mailbox 426, 22 Hankou Road, Nanjing, 210093, China
| | - Bin Li
- State Key Laboratory of Pharmaceutical Biotechnology and Department of Biological Science and Technology, School of Life Sciences, Nanjing University, Mailbox 426, 22 Hankou Road, Nanjing, 210093, China
| | - Guan-Yi Wu
- State Key Laboratory of Pharmaceutical Biotechnology and Department of Biological Science and Technology, School of Life Sciences, Nanjing University, Mailbox 426, 22 Hankou Road, Nanjing, 210093, China
| | - Wing-Ho Yung
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Jing-Ning Zhu
- State Key Laboratory of Pharmaceutical Biotechnology and Department of Biological Science and Technology, School of Life Sciences, Nanjing University, Mailbox 426, 22 Hankou Road, Nanjing, 210093, China.
| | - Jian-Jun Wang
- State Key Laboratory of Pharmaceutical Biotechnology and Department of Biological Science and Technology, School of Life Sciences, Nanjing University, Mailbox 426, 22 Hankou Road, Nanjing, 210093, China.
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22
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Yiu A, Mercaldo V, Yan C, Richards B, Rashid A, Hsiang HL, Pressey J, Mahadevan V, Tran M, Kushner S, Woodin M, Frankland P, Josselyn S. Neurons Are Recruited to a Memory Trace Based on Relative Neuronal Excitability Immediately before Training. Neuron 2014; 83:722-35. [DOI: 10.1016/j.neuron.2014.07.017] [Citation(s) in RCA: 213] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/02/2014] [Indexed: 10/24/2022]
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23
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Wang D, Schreurs BG. Maturation of membrane properties of neurons in the rat deep cerebellar nuclei. Dev Neurobiol 2014; 74:1268-76. [PMID: 24931427 DOI: 10.1002/dneu.22203] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 05/25/2014] [Accepted: 06/10/2014] [Indexed: 12/20/2022]
Abstract
Patch clamp recordings of neurons in the adult rat deep cerebellar nuclei have been limited by the availability of viable brain slices. Using a new slicing technique, this study was designed to explore the maturation of membrane properties of neurons in the deep cerebellar nuclei (DCN)-an area involved in rat eyeblink conditioning. Compared to whole-cell current-clamp recordings in DCN in rat pups at postnatal day 16 (P16) to P21, recordings from weanling rats at P22-P40 revealed a number of significant changes including an increase in the amplitude of the afterhyperpolarization (AHP)-an index of membrane excitability which has been shown to be important for eyeblink conditioning-a prolonged interval between the first and second evoked action potential, and an increase in AHP amplitude for hyperpolarization-induced rebound spikes. This is the first report of developmental changes in membrane properties of DCN which may contribute to the ontogeny of eyeblink conditioning in the rat.
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Affiliation(s)
- Desheng Wang
- Department of Physiology and Pharmacology, West Virginia University School of Medicine, Morgantown, West Virginia, 26506; Blanchette Rockefeller Neurosciences Institute, Morgantown, West Virginia, 26505
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24
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Activity-dependent neurotrophin signaling underlies developmental switch of Ca2+ channel subtypes mediating neurotransmitter release. J Neurosci 2014; 33:18755-63. [PMID: 24285882 DOI: 10.1523/jneurosci.3161-13.2013] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
At the nerve terminal, neurotransmitter release is triggered by Ca(2+) influx through voltage-gated Ca(2+) channels (VGCCs). During postnatal development, VGCC subtypes in the nerve terminal switch at many synapses. In immature rodent cerebella, N-type and P/Q-type VGCCs mediate GABAergic neurotransmission from Purkinje cells (PCs) to deep nuclear cells, but as animals mature, neurotransmission becomes entirely P/Q-type dependent. We reproduced this developmental switch in rat cerebellar slice culture to address the underlying mechanism. Chronic block of cerebellar neuronal activity with tetrodotoxin (TTX) in slice culture, or in vivo, reversed the switch, leaving neurotransmission predominantly N-type channel-dependent. Brain-derived neurotrophic factor or neurotrophin-4 rescued this TTX effect, whereas pharmacological blockade of neurotrophin receptors mimicked the TTX effect. In PC somata, unlike in presynaptic terminals, TTX had no effect on the proportion of Ca(2+) channel subtype currents. We conclude that neuronal activity activates the neurotrophin-TrkB signaling pathway, thereby causing the N-to-P/Q channel switch in presynaptic terminals.
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25
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5-HT2A receptor-mediated excitation on cerebellar fastigial nucleus neurons and promotion of motor behaviors in rats. Pflugers Arch 2013; 466:1259-71. [PMID: 24145983 DOI: 10.1007/s00424-013-1378-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 09/16/2013] [Accepted: 10/08/2013] [Indexed: 10/26/2022]
Abstract
It has long been known that serotonergic afferent inputs are the third largest afferent population in the cerebellum after mossy fibers and climbing fibers. However, the role of serotonergic inputs in cerebellar-mediated motor behaviors is still largely unknown. Here, we show that only 5-HT2A receptors among the 5-HT2 receptor subfamily are expressed and localized in the rat cerebellar fastigial nucleus (FN), one of the ultimate outputs of the spinocerebellum precisely regulating trunk and limb movements. Remarkably, selective activation of 5-HT2A receptors evokes a postsynaptic excitatory effect on FN neurons in a concentration-dependent manner in vitro, which is in accord with the 5-HT-elicited excitation on the same tested neurons. Furthermore, selective 5-HT2A receptor antagonist M100907 concentration-dependently blocks the excitatory effects of 5-HT and TCB-2, a 5-HT2A receptor agonist, on FN neurons. Consequently, microinjection of 5-HT into bilateral FNs significantly promotes rat motor performances on accelerating rota-rod and balance beam and narrows stride width rather than stride length in locomotion gait. All these motor behavioral effects are highly consistent with those of selective activation of 5-HT2A receptors in FNs, and blockage of the component of 5-HT2A receptor-mediated endogenous serotonergic inputs in FNs markedly attenuates these motor performances. All these results demonstrate that postsynaptic 5-HT2A receptors greatly contribute to the 5-HT-mediated excitatory effect on cerebellar FN neurons and promotion of the FN-related motor behaviors, suggesting that serotonergic afferent inputs may actively participate in cerebellar motor control through their direct modulation on the final output of the spinocerebellum.
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26
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Correlations in ion channel expression emerge from homeostatic tuning rules. Proc Natl Acad Sci U S A 2013; 110:E2645-54. [PMID: 23798391 DOI: 10.1073/pnas.1309966110] [Citation(s) in RCA: 147] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Experimental observations reveal that the expression levels of different ion channels vary across neurons of a defined type, even when these neurons exhibit stereotyped electrical properties. However, there are robust correlations between different ion channel expression levels, although the mechanisms that determine these correlations are unknown. Using generic model neurons, we show that correlated conductance expression can emerge from simple homeostatic control mechanisms that couple expression rates of individual conductances to cellular readouts of activity. The correlations depend on the relative rates of expression of different conductances. Thus, variability is consistent with homeostatic regulation and the structure of this variability reveals quantitative relations between regulation dynamics of different conductances. Furthermore, we show that homeostatic regulation is remarkably insensitive to the details that couple the regulation of a given conductance to overall neuronal activity because of degeneracy in the function of multiple conductances and can be robust to "antihomeostatic" regulation of a subset of conductances expressed in a cell.
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27
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Schneider ER, Civillico EF, Wang SSH. Calcium-based dendritic excitability and its regulation in the deep cerebellar nuclei. J Neurophysiol 2013; 109:2282-92. [PMID: 23427305 DOI: 10.1152/jn.00925.2012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The deep cerebellar nuclei (DCN) convey the final output of the cerebellum and are a major site of activity-dependent plasticity. Here, using patch-clamp recording and two-photon calcium imaging in rat brain slices, we demonstrate that DCN dendrites exhibit three hallmarks of active amplification of electrical signals. First, they produce calcium transients with rise times of tens of milliseconds, comparable in amplitude and duration to calcium spikes in other neurons. Second, calcium signal amplitudes are undiminished along the length of dendrites to the farthest distances from the soma. Third, they can generate calcium signals even in the presence of tetrodotoxin, a sodium channel blocker that abolishes somatic action potential initiation. DCN calcium transients do require the action of T-type calcium channels, a common voltage-gated conductance in excitable dendrites. Dendritic calcium influx was evoked by release from hyperpolarization, peaked within tens of milliseconds, and was observed in both transient- and weak-rebound-firing neurons. In a survey across the DCN, transient-burst rebound firing, which was accompanied by the most rapid calcium flux, was more common in lateral nucleus than in interpositus nucleus and was not seen in medial nucleus. Rebound firing and calcium transients were not present in animals shipped 1-3 days before recording, a condition associated with elevated maternal and pup corticosterone and reduced pup body weight. Rebounds could be restored by the protein kinase C activator phorbol 12-myristate-13-acetate. Thus local calcium-based dendritic excitability supports a stage of presomatic amplification that is under regulation by stress and neuromodulatory influence.
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Affiliation(s)
- Eve R Schneider
- Department of Psychology, Princeton University, Princeton, NJ, USA
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28
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Control of cerebellar nuclear cells: a direct role for complex spikes? THE CEREBELLUM 2012; 10:694-701. [PMID: 21373863 DOI: 10.1007/s12311-011-0261-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The question of what modulates the firing of the cerebellar nuclei (CN) is one to which we presently have a surprisingly incomplete answer. Because most synaptic input to the CN originates from Purkinje cells (PCs), and simple spikes (SSs) are far more numerous than complex spikes (CSs), SSs are generally thought to be the dominant influence on the CN. However, evidence, reviewed here, suggests that this appears not to be the case in some physiologically important situations. As an alternative, we propose that CS activity may have at least as significant an effect on CN firing as do SSs. In particular, we suggest that CS activity has a role in controlling the bursts CN neurons show during various movements, during sleep states, and under ketamine-xylazine anesthesia. The ability to perform this role rests on the fact that CSs can be highly synchronized among PCs that project to the same CN neuron. Specifically, we suggest that synchronized CSs help determine the temporal course of the CN bursts, most often their offset, and that SSs and activity from cerebellar afferents may modulate the specific firing pattern within each burst. This joint control of CN activity may help explain anomalies present in the standard model for synaptic control of CN activity in which determination of CN firing patterns is attributed primarily to SSs.
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29
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Uusisaari M, Knöpfel T. Functional classification of neurons in the mouse lateral cerebellar nuclei. THE CEREBELLUM 2012; 10:637-46. [PMID: 21116763 PMCID: PMC3215887 DOI: 10.1007/s12311-010-0240-3] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The deep cerebellar nuclei (DCN) are at the center of the cerebellum not only anatomically but also functionally. Classical anatomical studies have described different types of DCN neurons according to their expression of various marker proteins, but only recently have we begun to characterize these different cell types according to their electrophysiological properties. These efforts have benefited greatly from the availability of transgenic mouse lines that express green fluorescent protein under the control of the glutamic acid decarboxylase (GAD67) and glycine transporter (GlyT2) promoters, which are markers for GABAergic and glycinergic neurons, respectively. These studies have identified several types of neurons within the lateral cerebellar nuclei, each of which exhibits distinct active membrane properties. In addition to their differential use of neurotransmitters (glutamate, GABA, or glycine), these cell types also receive and provide synaptic information from different sources and to different targets.
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Affiliation(s)
- Marylka Uusisaari
- Laboratory for Neuronal Circuit Dynamics, RIKEN Brain Science Institute, Wako-shi, Saitama 351-0198 Japan
- Theoretical and Experimental Neurobiology Unit, OIST, Onna, Okinawa 904-0412 Japan
| | - Thomas Knöpfel
- Laboratory for Neuronal Circuit Dynamics, RIKEN Brain Science Institute, Wako-shi, Saitama 351-0198 Japan
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Isaeva VV, Kasyanov NV, Presnov EV. Topological singularities and symmetry breaking in development. Biosystems 2012; 109:280-98. [PMID: 22609746 DOI: 10.1016/j.biosystems.2012.05.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2012] [Revised: 05/10/2012] [Accepted: 05/10/2012] [Indexed: 11/18/2022]
Abstract
The review presents a topological interpretation of some morphogenetic events through the use of well-known mathematical concepts and theorems. Spatial organization of the biological fields is analyzable in topological terms. Topological singularities inevitably emerging in biological morphogenesis are retained and transformed during pattern formation. It is the topological language that can provide strict and adequate description of various phenomena in developmental and evolutionary transformations. The relationship between local and global orders in metazoan development, i.e., between local morphogenetic processes and integral developmental patterns, is established. A topological inevitability of some developmental events through the use of classical topological concepts is discussed. This methodology reveals a topological imperative as a certain set of topological rules that constrains and directs embryogenesis. A breaking of spatial symmetry of preexisting pattern plays a critical role in biological morphogenesis in development and evolution.
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Affiliation(s)
- Valeria V Isaeva
- A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of Science, 119071 Moscow, Russia.
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He YC, Wu GY, Li D, Tang B, Li B, Ding Y, Zhu JN, Wang JJ. Histamine promotes rat motor performances by activation of H(2) receptors in the cerebellar fastigial nucleus. Behav Brain Res 2011; 228:44-52. [PMID: 22146592 DOI: 10.1016/j.bbr.2011.11.029] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 11/16/2011] [Accepted: 11/21/2011] [Indexed: 11/19/2022]
Abstract
The cerebellar fastigial nucleus (FN), together with the interpositus nucleus (IN), constitutes the two final output nuclei of the spinocerebellum and plays an important role in body and limb movements. Previous studies have revealed a direct histaminergic projection from the hypothalamus to the cerebellar nuclei and an excitatory effect of histamine on the IN neurons. However, role of hypothalamic histaminergic projection in the FN has been still little known. Here we show that histamine elicited the FN neurons of rats a concentration-dependent excitatory response in vitro. The histamine-induced excitation on FN neurons was mediated by postsynaptic histamine H2 rather than H1 receptors. In behavioral tests, microinjection of histamine into bilateral FNs remarkably improved motor performances of rats on both accelerating rota-rod and balance beam. Selective H2 receptor antagonist ranitidine considerably declined those motor performances and selective H2 receptor agonist dimaprit mimicked the facilitation effect of histamine on the movements. But selective H1 receptor antagonist triprolidine and agonist 2-pyridylethylamine had no effect. Furthermore, microinjection of histamine into bilateral FNs narrowed stride width of footprint but did not influence wire suspension, whereas microinjection of histamine into bilateral INs increased stride length and promoted suspension. These results demonstrate that histamine enhances rat motor balance and coordination through modulation of both proximal and distal muscles by activation of histamine H2 receptors in the cerebellar FN and IN, and suggest that the hypothalamocerebellar histaminergic projections may modulate the final outputs of the spinocerebellum and participate in the cerebellum-mediated motor control.
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Affiliation(s)
- Ye-Cheng He
- Department of Biological Science and Technology and State Key Laboratory of Pharmaceutical Biotechnology, Mailbox 426, School of Life Sciences, Nanjing University, 22 Hankou Road, Nanjing 210093, China
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Uusisaari M, De Schutter E. The mysterious microcircuitry of the cerebellar nuclei. J Physiol 2011; 589:3441-57. [PMID: 21521761 PMCID: PMC3167109 DOI: 10.1113/jphysiol.2010.201582] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2011] [Accepted: 04/20/2011] [Indexed: 11/08/2022] Open
Abstract
The microcircuitry of cerebellar cortex and, in particular, the physiology of its main element, the Purkinje neuron, has been extensively investigated and described. However, activity in Purkinje neurons, either as single cells or populations, does not directly mediate the cerebellar effects on the motor effector systems. Rather, the result of the entire cerebellar cortical computation is passed to the relatively small cerebellar nuclei that act as the final, integrative processing unit in the cerebellar circuitry. The nuclei ultimately control the temporal and spatial features of the cerebellar output. Given this key role, it is striking that the internal organization and the connectivity with afferent and efferent pathways in the cerebellar nuclei are rather poorly known. In the present review, we discuss some of the many critical shortcomings in the understanding of cerebellar nuclei microcircuitry: the extent of convergence and divergence of the cerebellar cortical pathway to the various cerebellar nuclei neurons and subareas, the possible (lack of) conservation of the finely-divided topographical organization in the cerebellar cortex at the level of the nuclei, as well as the absence of knowledge of the synaptic circuitry within the cerebellar nuclei. All these issues are important for predicting the pattern-extraction and encoding capabilities of the cerebellar nuclei and, until resolved, theories and models of cerebellar motor control and learning may err considerably.
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Affiliation(s)
- Marylka Uusisaari
- Theoretical and Experimental Neurobiology Unit, Okinawa Institute of Science and Technology, 7542 Onna, Onna-son, Okinawa 904-0411, Japan.
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Tadayonnejad R, Anderson D, Molineux ML, Mehaffey WH, Jayasuriya K, Turner RW. Rebound discharge in deep cerebellar nuclear neurons in vitro. THE CEREBELLUM 2011; 9:352-74. [PMID: 20396983 PMCID: PMC2949560 DOI: 10.1007/s12311-010-0168-7] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Neurons of the deep cerebellar nuclei (DCN) play a critical role in defining the output of cerebellum in the course of encoding Purkinje cell inhibitory inputs. The earliest work performed with in vitro preparations established that DCN cells have the capacity to translate membrane hyperpolarizations into a rebound increase in firing frequency. The primary means of distinguishing between DCN neurons has been according to cell size and transmitter phenotype, but in some cases, differences in the firing properties of DCN cells maintained in vitro have been reported. In particular, it was shown that large diameter cells in the rat DCN exhibit two phenotypes of rebound discharge in vitro that may eventually help define their functional roles in cerebellar output. A transient burst and weak burst phenotype can be distinguished based on the frequency and pattern of rebound discharge immediately following a hyperpolarizing stimulus. Work to date indicates that the difference in excitability arises from at least the degree of activation of T-type Ca(2+) current during the immediate phase of rebound firing and Ca(2+)-dependent K(+) channels that underlie afterhyperpolarizations. Both phenotypes can be detected following stimulation of Purkinje cell inhibitory inputs under conditions that preserve resting membrane potential and natural ionic gradients. In this paper, we review the evidence supporting the existence of different rebound phenotypes in DCN cells and the ion channel expression patterns that underlie their generation.
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Affiliation(s)
- Reza Tadayonnejad
- Department of Cell Biology & Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta Canada T2N 4N1
| | - Dustin Anderson
- Department of Cell Biology & Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta Canada T2N 4N1
| | - Michael L. Molineux
- Department of Cell Biology & Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta Canada T2N 4N1
| | - W. Hamish Mehaffey
- Department of Cell Biology & Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta Canada T2N 4N1
| | - Kusala Jayasuriya
- Department of Cell Biology & Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta Canada T2N 4N1
| | - Ray W. Turner
- Department of Cell Biology & Anatomy, Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta Canada T2N 4N1
- Hotchkiss Brain Institute, HRIC 1AA14, University of Calgary, 3330 Hospital Dr. N.W., Calgary, Alberta Canada T2N 4N1
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Sangrey T, Jaeger D. Analysis of distinct short and prolonged components in rebound spiking of deep cerebellar nucleus neurons. Eur J Neurosci 2010; 32:1646-57. [PMID: 21039958 DOI: 10.1111/j.1460-9568.2010.07408.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Deep cerebellar nucleus (DCN) neurons show pronounced post-hyperpolarization rebound burst behavior, which may contribute significantly to responses to strong inhibitory inputs from cerebellar cortical Purkinje cells. Thus, rebound behavior could importantly shape the output from the cerebellum. We used whole-cell recordings in brain slices to characterize DCN rebound properties and their dependence on hyperpolarization duration and depth. We found that DCN rebounds showed distinct fast and prolonged components, with different stimulus dependence and different underlying currents. The initial depolarization leading into rebound spiking was carried by hyperpolarization-activated cyclic nucleotide-gated current, and variable expression of this current could lead to a control of rebound latency. The ensuing fast rebound burst was due to T-type calcium current, as previously described. It was highly variable between cells in strength, and could be expressed fully after short periods of hyperpolarization. In contrast, a subsequent prolonged rebound component required longer and deeper periods of hyperpolarization before it was fully established. We found using voltage-clamp and dynamic-clamp analyses that a slowly inactivating persistent sodium current fits the conductance underlying this prolonged rebound component, resulting in spike rate increases over several seconds. Overall, our results demonstrate that multiphasic DCN rebound properties could be elicited differentially by different levels of Purkinje cell activation, and thus create a rich repertoire of potential rebound dynamics in the cerebellar control of motor timing.
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Affiliation(s)
- Thomas Sangrey
- Department of Biology, Emory University, Atlanta, GA, USA
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35
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Cerminara NL, Rawson JA, Apps R. Electrophysiological characterization of the cerebellum in the arterially perfused hindbrain and upper body of the rat. THE CEREBELLUM 2010; 9:218-31. [PMID: 20033360 PMCID: PMC2866334 DOI: 10.1007/s12311-009-0152-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In the present study, a non-pulsatile arterially perfused hindbrain and upper body rat preparation is described which is an extension of the brainstem preparation reported by Potts et al., (Brain Res Bull 53(1):59-67), 1. The modified in situ preparation allows study of cerebellar function whilst preserving the integrity of many of its interconnections with the brainstem, upper spinal cord and the peripheral nervous system of the head and forelimbs. Evoked mossy fibre, climbing fibre and parallel fibre field potentials and EMG activity elicited in forelimb biceps muscle by interpositus stimulation provided evidence that both cerebellar inputs and outputs remain operational in this preparation. Similarly, the spontaneous and evoked single unit activity of Purkinje cells, putative Golgi cells, molecular interneurones and cerebellar nuclear neurones was similar to activity patterns reported in vivo. The advantages of the preparation include the ability to record, without the complications of anaesthesia, stabile single unit activity for extended periods (3 h or more), from regions of the rat cerebellum that are difficult to access in vivo. The preparation should therefore be a useful adjunct to in vitro and in vivo studies of neural circuits underlying cerebellar contributions to movement control and motor learning.
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Affiliation(s)
- Nadia L Cerminara
- Department of Physiology and Pharmacology, University of Bristol, UK.
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36
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Orexins excite neurons of the rat cerebellar nucleus interpositus via orexin 2 receptors in vitro. THE CEREBELLUM 2010; 9:88-95. [PMID: 19921532 DOI: 10.1007/s12311-009-0146-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Orexins are newfound hypothalamic neuropeptides implicated in the regulation of feeding behavior, sleep-wakefulness cycle, nociception, addiction, emotions, as well as narcolepsy. However, little is known about roles of orexins in motor control. Therefore, the present study was designed to investigate the effect of orexins on neuronal activity in the cerebellum, an important subcortical center for motor control. In this study, perfusing slices with orexin A (100 nM-1 microM) or orexin B (100 nM-1 microM) both produced neurons in the rat cerebellar interpositus nucleus (IN) a concentration-dependent excitatory response (96/143, 67.1%). Furthermore, both of the excitations induced by orexin A and B were not blocked by the low-Ca(2+)/high-Mg(2+) medium (n = 8), supporting a direct postsynaptic action of the peptides. Highly selective orexin 1 receptor antagonist SB-334867 did not block the excitatory response of cerebellar IN neurons to orexins (n = 22), but [Ala(11), D-Leu(15)] orexin B, a highly selective orexin 2 receptor (OX(2)R) agonist, mimicked the excitatory effect of orexins on the cerebellar neurons (n = 18). These results demonstrate that orexins excite the cerebellar IN neurons through OX(2)R and suggest that the central orexinergic nervous system may actively participate in motor control through its modulation on one of the final outputs of the spinocerebellum.
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Wilson GW, Garthwaite J. Hyperpolarization-activated ion channels as targets for nitric oxide signalling in deep cerebellar nuclei. Eur J Neurosci 2010; 31:1935-45. [PMID: 20529121 PMCID: PMC2955965 DOI: 10.1111/j.1460-9568.2010.07226.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Most biological effects of nitric oxide (NO) in the brain are mediated by guanylyl cyclase-coupled NO receptors, whose activation results in increased intracellular cGMP levels. Apart from protein kinase activation little is known about subsequent cGMP signal transduction. In optic nerve axons, hyperpolarization-activated cyclic nucleotide-modulated cation (HCN) channels, which bind cGMP or cAMP directly, were recently suggested to be a target. The aim here was to test this possibility more directly. Neurones of the rat deep cerebellar nuclei were selected for this purpose, their suitability being attested by immunocytochemistry showing that the principal neurones expressed guanylyl cyclase protein and that NO synthase-containing fibres were abundant in the neuropil. Using whole-cell voltage-clamp recording, HCN channels in the neurones were activated in response to isoprenaline and exogenous cAMP but only occasionally did they respond to NO, although exogenous cGMP was routinely effective. With the less invasive sharp microelectrode recording technique, however, exogenous NO modulated the channels reproducibly, as measured by the size of the HCN channel-mediated voltage sag following hyperpolarization. Moreover, NO also blunted the subsequent rebound depolarizing potentials, consistent with it increasing the hyperpolarization-activated current. Optimizing the whole-cell solution to improve the functioning of NO-activated guanylyl cyclase failed to restore NO sensitivity. Minimizing cellular dialysis by using the perforated-patch technique, however, was successful. The results provide evidence that HCN channels are potential downstream mediators of NO signalling in deep cerebellar nuclei neurones and suggest that the more general importance of this transduction pathway may have been overlooked previously because of unsuitable recording methods.
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Affiliation(s)
- Gary W Wilson
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London WC1E 6BT, UK.
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38
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Rescue of motor coordination by Purkinje cell-targeted restoration of Kv3.3 channels in Kcnc3-null mice requires Kcnc1. J Neurosci 2010; 29:15735-44. [PMID: 20016089 DOI: 10.1523/jneurosci.4048-09.2009] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The role of cerebellar Kv3.1 and Kv3.3 channels in motor coordination was examined with an emphasis on the deep cerebellar nuclei (DCN). Kv3 channel subunits encoded by Kcnc genes are distinguished by rapid activation and deactivation kinetics that support high-frequency, narrow action potential firing. Previously we reported that increased lateral deviation while ambulating and slips while traversing a narrow beam of ataxic Kcnc3-null mice were corrected by restoration of Kv3.3 channels specifically to Purkinje cells, whereas Kcnc3-mutant mice additionally lacking one Kcnc1 allele were partially rescued. Here, we report mice lacking all Kcnc1 and Kcnc3 alleles exhibit no such rescue. For Purkinje cell output to reach the rest of the brain it must be conveyed by neurons of the DCN or vestibular nuclei. As Kcnc1, but not Kcnc3, alleles are lost, mutant mice exhibit increasing gait ataxia accompanied by spike broadening and deceleration in DCN neurons, suggesting the facet of coordination rescued by Purkinje-cell-restricted Kv3.3 restoration in mice lacking just Kcnc3 is hypermetria, while gait ataxia emerges when additionally Kcnc1 alleles are lost. Thus, fast repolarization in Purkinje cells appears important for normal movement velocity, whereas DCN neurons are a prime candidate locus where fast repolarization is necessary for normal gait patterning.
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39
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Baumel Y, Jacobson GA, Cohen D. Implications of functional anatomy on information processing in the deep cerebellar nuclei. Front Cell Neurosci 2009; 3:14. [PMID: 19949453 PMCID: PMC2783015 DOI: 10.3389/neuro.03.014.2009] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2009] [Accepted: 11/08/2009] [Indexed: 12/31/2022] Open
Abstract
The cerebellum has been implicated as a major player in producing temporal acuity. Theories of cerebellar timing typically emphasize the role of the cerebellar cortex while overlooking the role of the deep cerebellar nuclei (DCN) that provide the sole output of the cerebellum. Here we review anatomical and electrophysiological studies to shed light on the DCN's ability to support temporal pattern generation in the cerebellum. Specifically, we examine data on the structure of the DCN, the biophysical properties of DCN neurons and properties of the afferent systems to evaluate their contribution to DCN firing patterns. In addition, we manipulate one of the afferent structures, the inferior olive (IO), using systemic harmaline injection to test for a network effect on activity of single DCN neurons in freely moving animals. Harmaline induces a rhythmic firing pattern of short bursts on a quiescent background at about 8 Hz. Other neurons become quiescent for long periods (seconds to minutes). The observed patterns indicate that the major effect harmaline exerts on the DCN is carried indirectly by the inhibitory Purkinje cells (PCs) activated by the IO, rather than by direct olivary excitation. Moreover, we suggest that the DCN response profile is determined primarily by the number of concurrently active PCs, their firing rate and the level of synchrony occurring in their transitions between continuous firing and quiescence. We argue that DCN neurons faithfully transfer temporal patterns resulting from strong correlations in PCs state transitions, while largely ignoring the timing of simple spikes from individual PCs. Future research should aim at quantifying the contribution of PC state transitions to DCN activity, and the interplay between the different afferent systems that drive DCN activity.
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Affiliation(s)
- Yuval Baumel
- Gonda Interdisciplinary Brain Research Center, Bar Ilan UniversityRamat Gan, Israel
| | - Gilad A. Jacobson
- Friedrich Miescher Institute for Biomedical ResearchBasel, Switzerland
| | - Dana Cohen
- Gonda Interdisciplinary Brain Research Center, Bar Ilan UniversityRamat Gan, Israel
- The Goodman Faculty of Life Sciences, Bar Ilan UniversityRamat Gan, Israel
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40
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Abstract
The cerebellum funnels its entire output through a small number of presumed glutamatergic premotor projection neurons in the deep cerebellar nuclei and GABAergic neurons that feed back to the inferior olive. Here we use transgenic mice selectively expressing green fluorescent protein in glycinergic neurons to demonstrate that many premotor output neurons in the medial cerebellar (fastigial) nuclei are in fact glycinergic, not glutamatergic as previously thought. These neurons exhibit similar firing properties as neighboring glutamatergic neurons and receive direct input from both Purkinje cells and excitatory fibers. Glycinergic fastigial neurons make functional projections to vestibular and reticular neurons in the ipsilateral brainstem, whereas their glutamatergic counterparts project contralaterally. Together, these data suggest that the cerebellum can influence motor outputs via two distinct and complementary pathways.
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41
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Joho RH, Hurlock EC. The role of Kv3-type potassium channels in cerebellar physiology and behavior. THE CEREBELLUM 2009; 8:323-33. [PMID: 19247732 DOI: 10.1007/s12311-009-0098-4] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2008] [Accepted: 02/10/2009] [Indexed: 10/21/2022]
Abstract
Different subunits of the Kv3 subfamily of voltage-gated potassium (Kv) channels (Kv3.1-Kv3.4) are expressed in distinct neuronal subpopulations in the cerebellum. Behavioral phenotypes in Kv3-null mutant mice such as ataxia with prominent hypermetria and heightened alcohol sensitivity are characteristic of cerebellar dysfunction. Here, we review how the unique biophysical properties of Kv3-type potassium channels, fast activation and fast deactivation that enable cerebellar neurons to generate brief action potentials at high frequencies, affect firing patterns and influence cerebellum-mediated behavior.
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Affiliation(s)
- Rolf H Joho
- Department of Neuroscience, The University of Texas Southwestern Medical Center, Dallas, TX 75390-9111, USA.
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Saitow F, Murano M, Suzuki H. Modulatory effects of serotonin on GABAergic synaptic transmission and membrane properties in the deep cerebellar nuclei. J Neurophysiol 2009; 101:1361-74. [PMID: 19144744 DOI: 10.1152/jn.90750.2008] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cerebellar outputs from the deep cerebellar nuclei (DCN) are critical for generating and controlling movement. DCN neuronal activity is primarily controlled by GABAergic inhibitory transmission by Purkinje cells in the cerebellar cortex and is also modulated by nerve inputs originating from other brain regions within and outside the cerebellum. In this study, we examined the modulatory effects of 5-HT on GABAergic synapses in the DCN. 5-HT decreased the amplitude of stimulation-evoked inhibitory postsynaptic currents (eIPSCs) in DCN neurons, and this effect was abolished by a 5-HT(1B) antagonist, SB 224289. The decrease in IPSC amplitude was associated with an increased paired-pulse ratio of the IPSC. 5-HT also decreased the frequency of miniature IPSCs without altering the amplitude. These data suggest that 5-HT presynaptically inhibited GABA release. Furthermore, 5-HT elicited a slow inward current in DCN neurons. Pharmacological studies showed that 5-HT activated the 5-HT(5) receptor, which is positively coupled to G protein and elicited the slow inward current through enhancement of hyperpolarization-activated cation channel activation. Finally, we examined the effects of 5-HT on the spike generation that accompanies repetitive stimulation of inhibitory synapses. 5-HT increased the spontaneous firing rate in DCN neurons caused by depolarization. Increase in the 5-HT-induced tonic firing relatively decreased the contrast difference from the rebound depolarization-induced firing. However, the inhibitory transmission-induced silencing of DCN firing remained during the conditioning stimulus. These results suggest that 5-HT plays a regulatory role in spike generation and contributes to the gain control of inhibitory GABAergic synapses in DCN neurons.
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Affiliation(s)
- Fumihito Saitow
- Department of Pharmacology, Nippon Medical School, Tokyo, Japan.
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43
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Uusisaari M, Knöpfel T. GABAergic synaptic communication in the GABAergic and non-GABAergic cells in the deep cerebellar nuclei. Neuroscience 2008; 156:537-49. [PMID: 18755250 DOI: 10.1016/j.neuroscience.2008.07.060] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Revised: 07/29/2008] [Accepted: 07/29/2008] [Indexed: 11/29/2022]
Abstract
The deep cerebellar nuclei (DCN) are the final integrative units of the cerebellar network. The strongest single afferent to the DCN is formed by GABAergic Purkinje neuron axons whose synapses constitute the majority of all synapses in the DCN, with their action strongly regulating the intrinsic activity of their target neurons. Although this is well established, it remains unclear whether all DCN cell groups receive a functionally similar inhibitory input. We previously characterized three types of mouse DCN neurons based on the expression of glutamic acid decarboxylase isoform 67 (GAD67), their active membrane properties and morphological features. Here we describe the GABAergic synapses in these cell groups and show that spontaneous GABAergic synaptic activity can be seen in all three cell types. Since the majority of DCN neurons fire action potentials spontaneously at high frequencies both in vivo and in vitro, we expected that spontaneous GABAergic synaptic activities mediated by intra-DCN synaptic connections could be uncovered by their sensitivity to TTX. However, TTX had little effect on spontaneous synaptic activity. It seems, therefore that functional GABAergic connectivity within the DCN is sparse and/or weak at least under our experimental conditions. Even though present in all cell types, the spontaneous GABAergic events showed significant differences between the cell types. The synaptic currents in GABAergic cells had lower amplitude, lower frequency and slower kinetics than those of non-GABAergic cells. These differences could not be sufficiently explained by considering only cell size differences or a differential GABA(A)-receptor alpha-subunit composition. Rather, the main differentiating factor appears to be the dendritic localization of GABAergic synapses in the GABAergic cells.
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Affiliation(s)
- M Uusisaari
- Laboratory for Neuronal Circuit Dynamics, Brain Science Institute, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama, 351-0198, Japan
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44
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Brennaman LH, Maness PF. Developmental regulation of GABAergic interneuron branching and synaptic development in the prefrontal cortex by soluble neural cell adhesion molecule. Mol Cell Neurosci 2008; 37:781-93. [PMID: 18289872 DOI: 10.1016/j.mcn.2008.01.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2007] [Revised: 12/17/2007] [Accepted: 01/04/2008] [Indexed: 11/24/2022] Open
Abstract
Neural cell adhesion molecule, NCAM, is an important regulator of neuronal process outgrowth and synaptic plasticity. Transgenic mice that overexpress the soluble NCAM extracellular domain (NCAM-EC) have reduced GABAergic inhibitory and excitatory synapses, and altered behavioral phenotypes. Here, we examined the role of dysregulated NCAM shedding, modeled by overexpression of NCAM-EC, on development of GABAergic basket interneurons in the prefrontal cortex. NCAM-EC overexpression disrupted arborization of basket cells during the major period of axon/dendrite growth, resulting in decreased numbers of GAD65- and synaptophysin-positive perisomatic synapses. NCAM-EC transgenic protein interfered with interneuron branching during early postnatal stages when endogenous polysialylated (PSA) NCAM was converted to non-PSA isoforms. In cortical neuron cultures, soluble NCAM-EC acted as a dominant inhibitor of NCAM-dependent neurite branching and outgrowth. These findings suggested that excess soluble NCAM-EC reduces perisomatic innervation of cortical neurons by perturbing axonal/dendritic branching during cortical development.
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Affiliation(s)
- Leann Hinkle Brennaman
- Department of Biochemistry and Biophysics, and Silvio Conte Center for Schizophrenia Research, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
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45
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Tang B, Zhang J, Li H, Zhu J, Wang J. Excitatory effect of histamine on neuronal activity of rat cerebellar fastigial nucleus in vitro. ACTA ACUST UNITED AC 2007. [DOI: 10.1007/s11434-007-0101-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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46
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Uusisaari M, Obata K, Knöpfel T. Morphological and electrophysiological properties of GABAergic and non-GABAergic cells in the deep cerebellar nuclei. J Neurophysiol 2006; 97:901-11. [PMID: 17093116 DOI: 10.1152/jn.00974.2006] [Citation(s) in RCA: 155] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The deep cerebellar nuclei (DCN) integrate inputs from the brain stem, the inferior olive, and the spinal cord with Purkinje cell output from cerebellar cortex and provide the major output of the cerebellum. Despite their crucial function in motor control and learning, the various populations of neurons in the DCN are poorly defined and characterized. Importantly, differences in electrophysiological properties between glutamatergic and GABAergic cells of the DCN have been largely elusive. Here, we used glutamate decarboxylase (GAD) 67-green fluorescent protein (GFP) knock-in mice to unambiguously identify GABAergic (GAD-positive) and non-GABAergic (GAD-negative, most likely glutamatergic) neurons of the DCN. Morphological analysis of DCN neurons patch-clamped with biocytin-containing electrodes revealed a significant overlap in the distributions of the soma sizes of GAD-positive and GAD-negative cells. Compared with GAD-negative DCN neurons, GAD-positive DCN neurons fire broader action potentials, display stronger frequency accommodation, and do not reach as high firing frequencies during depolarizing current injections. Furthermore, GAD-positive cells display slower spontaneous firing rates and have a more shallow frequency-to-current relationship than the GAD-negative cells but exhibit a longer-lasting rebound depolarization and associated spiking after a transient hyperpolarization. In contrast to the rather homogeneous population of GAD-positive cells, the GAD-negative cells were found to consist of two distinct populations as defined by cell size and electrophysiological features. We conclude that GABAergic DCN neurons are specialized to convey phasic spike rate information, whereas tonic spike rate is more faithfully relayed by the large non-GABAergic cells.
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Affiliation(s)
- Marylka Uusisaari
- Laboratory for Neuronal Circuit Dynamics, Brain Science Institute, RIKEN, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan
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Chen FP, Evinger C. Cerebellar modulation of trigeminal reflex blinks: interpositus neurons. J Neurosci 2006; 26:10569-76. [PMID: 17035543 PMCID: PMC6674682 DOI: 10.1523/jneurosci.0079-06.2006] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Revised: 09/07/2006] [Accepted: 09/08/2006] [Indexed: 11/21/2022] Open
Abstract
Because of its simplicity, blinking is a prominent model system in analysis of adaptation and conditioning with the cerebellum. Nevertheless, data on the role of the cerebellum in modulation of normal reflex blinks are limited. We correlated the discharge of interpositus (IP) neurons with normal trigeminal reflex blinks and blink adaptation in urethane-anesthetized rats. Two groups of IP neurons responded to cornea stimulation. One group, pause neurons, showed a long cessation of their tonic discharge beginning 6 ms before the end of lid closure. The second group, burst neurons, exhibited a transient increase in firing frequency at a constant interval after the cornea stimulus. The cessation of pause neuron activity appeared to contribute to the termination of blinks. The tonic discharge rate increased and the cessation of pause neuron activity was delayed coincident with increased amplitude and duration of reflex blinks produced by blink adaptation. There was a coincident increase in the amplitude and duration of reflex blinks with increased tonic activity and delayed pause in pause neurons treated with the GABA(A) antagonist, gabazine. Burst neurons did not appear to modulate reflex blinks. Burst neuron discharge correlated neither with blink characteristics normally nor with blink adaptation. These findings indicated that pause neurons affect reflex blinks by providing a tonic excitatory input to facial motoneurons during lid closure and then disfacilitating those motoneurons to adjust the termination of lid closure. Burst neurons may play a role in eyelid conditioning.
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Affiliation(s)
- Fang-Ping Chen
- Department of Biological Sciences, Stanford University, Stanford, California 94305, and
| | - Craig Evinger
- Department of Neurobiology and Behavior and Department of Ophthalmology, State University of New York at Stony Brook, Stony Brook, New York 11794
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Abstract
Several lines of evidence have indicated that the deep cerebellar nuclei (DCN) are a site of memory storage for certain forms of motor learning, most notably associative eyelid conditioning. In particular, these experiments, together with network models, have implicated the excitatory glutamatergic synapse between mossy fibers and DCN neurons in this memory trace. However, to date, evidence for persistent use-dependent change in the strength of this synapse has been almost entirely absent. Here, we report that high-frequency burst stimulation of mossy fibers, either alone or paired with postsynaptic depolarization, gives rise to long-term depression (LTD) of the mossy fiber-DCN synapse. This form of LTD is not associated with changes in the paired-pulse ratio and is blocked by loading with a postsynaptic Ca2+ chelator but not by bath application of an NMDA receptor antagonist. Mossy fiber-DCN LTD requires activation of a group I metabotropic glutamate receptor (mGluR) and protein translation. Unlike mGluR/translation-dependent LTD in other brain regions, this form of LTD requires mGluR1 and is mGluR5 independent.
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Iyer V, Hoogland TM, Saggau P. Fast functional imaging of single neurons using random-access multiphoton (RAMP) microscopy. J Neurophysiol 2005; 95:535-45. [PMID: 16221746 DOI: 10.1152/jn.00865.2005] [Citation(s) in RCA: 109] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The successful study of dendritic signaling and computation requires the ability to simultaneously monitor neuronal activity at multiple cellular sites. While the difficulties of accessing dendritic submicron structures with conventional micropipette approaches are generally overcome by optical recording techniques, their spatio-temporal resolution has limited such studies to few sites or slow signals. Here we present a novel approach to functional imaging, termed random-access multiphoton (RAMP) microscopy, which combines multiphoton excitation with an inertia-free scanning mechanism. RAMP microscopy employs two-dimensional acousto-optic deflection to rapidly position a focused near-infrared ultrafast laser beam between dwell periods at multiple user-selected sites. Because neuronal structures are generally sparse, activity located throughout various compartments, including thin dendritic branches and spines, can be mapped at high frame rates while maintaining the signal-to-noise ratio of conventional scanning microscopy. Moreover, RAMP microscopy maintains the excellent structural imaging capability of multiphoton excitation, i.e., intrinsic optical sectioning and high lateral resolution from within highly light-scattering brain tissue. RAMP microscopy thus comprises a versatile tool for investigating correlations of dendritic structure and function with significantly enhanced experimental throughput.
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Affiliation(s)
- Vijay Iyer
- Department of Neuroscience, One Baylor Plaza, S603, Houston, TX 77030, USA
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Abstract
Fragile X syndrome (FXS) is caused by the transcriptional silencing of the Fmr1 gene, which encodes a protein (FMRP) that can act as a translational suppressor in dendrites, and is characterized by a preponderance of abnormally long, thin and tortuous dendritic spines. According to a current theory of FXS, the loss of FMRP expression leads to an exaggeration of translation responses linked to group I metabotropic glutamate receptors. Such responses are involved in the consolidation of a form of long-term depression that is enhanced in Fmr1 knockout mice and in the elongation of dendritic spines, resembling synaptic phenotypes over-represented in fragile X brain. These observations place fragile X research at the heart of a long-standing issue in neuroscience. The consolidation of memory, and several distinct forms of synaptic plasticity considered to be substrates of memory, requires mRNA translation and is associated with changes in spine morphology. A recent convergence of research on FXS and on the involvement of translation in various forms of synaptic plasticity has been very informative on this issue and on mechanisms underlying FXS. Evidence suggests a general relationship in which the receptors that induce distinct forms of efficacy change differentially regulate translation to produce unique spine shapes involved in their consolidation. We discuss several potential mechanisms for differential translation and the notion that FXS represents an exaggeration of one 'channel' in a set of translation-dependent consolidation responses.
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Affiliation(s)
- P W Vanderklish
- Department of Neurobiology, The Scripps Research Institute, La Jolla, CA 92037, USA.
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