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Shinji Y, Okuno H, Hirata Y. Artificial cerebellum on FPGA: realistic real-time cerebellar spiking neural network model capable of real-world adaptive motor control. Front Neurosci 2024; 18:1220908. [PMID: 38726031 PMCID: PMC11079192 DOI: 10.3389/fnins.2024.1220908] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 04/09/2024] [Indexed: 05/12/2024] Open
Abstract
The cerebellum plays a central role in motor control and learning. Its neuronal network architecture, firing characteristics of component neurons, and learning rules at their synapses have been well understood in terms of anatomy and physiology. A realistic artificial cerebellum with mimetic network architecture and synaptic plasticity mechanisms may allow us to analyze cerebellar information processing in the real world by applying it to adaptive control of actual machines. Several artificial cerebellums have previously been constructed, but they require high-performance hardware to run in real-time for real-world machine control. Presently, we implemented an artificial cerebellum with the size of 104 spiking neuron models on a field-programmable gate array (FPGA) which is compact, lightweight, portable, and low-power-consumption. In the implementation three novel techniques are employed: (1) 16-bit fixed-point operation and randomized rounding, (2) fully connected spike information transmission, and (3) alternative memory that uses pseudo-random number generators. We demonstrate that the FPGA artificial cerebellum runs in real-time, and its component neuron models behave as those in the corresponding artificial cerebellum configured on a personal computer in Python. We applied the FPGA artificial cerebellum to the adaptive control of a machine in the real world and demonstrated that the artificial cerebellum is capable of adaptively reducing control error after sudden load changes. This is the first implementation and demonstration of a spiking artificial cerebellum on an FPGA applicable to real-world adaptive control. The FPGA artificial cerebellum may provide neuroscientific insights into cerebellar information processing in adaptive motor control and may be applied to various neuro-devices to augment and extend human motor control capabilities.
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Affiliation(s)
- Yusuke Shinji
- Department of Computer Science, Graduate School of Engineering, Chubu University, Kasugai, Japan
| | - Hirotsugu Okuno
- Faculty of Information Science and Technology, Osaka Institute of Technology, Hirakata, Japan
| | - Yutaka Hirata
- Department of Artificial Intelligence and Robotics, College of Engineering, Chubu University, Kasugai, Japan
- Center for Mathematical Science and Artificial Intelligence, Chubu University, Kasugai, Japan
- Academy of Emerging Sciences, Chubu University, Kasugai, Japan
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2
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Florini D, Gandolfi D, Mapelli J, Benatti L, Pavan P, Puglisi FM. A Hybrid CMOS-Memristor Spiking Neural Network Supporting Multiple Learning Rules. IEEE TRANSACTIONS ON NEURAL NETWORKS AND LEARNING SYSTEMS 2024; 35:5117-5129. [PMID: 36099218 DOI: 10.1109/tnnls.2022.3202501] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Artificial intelligence (AI) is changing the way computing is performed to cope with real-world, ill-defined tasks for which traditional algorithms fail. AI requires significant memory access, thus running into the von Neumann bottleneck when implemented in standard computing platforms. In this respect, low-latency energy-efficient in-memory computing can be achieved by exploiting emerging memristive devices, given their ability to emulate synaptic plasticity, which provides a path to design large-scale brain-inspired spiking neural networks (SNNs). Several plasticity rules have been described in the brain and their coexistence in the same network largely expands the computational capabilities of a given circuit. In this work, starting from the electrical characterization and modeling of the memristor device, we propose a neuro-synaptic architecture that co-integrates in a unique platform with a single type of synaptic device to implement two distinct learning rules, namely, the spike-timing-dependent plasticity (STDP) and the Bienenstock-Cooper-Munro (BCM). This architecture, by exploiting the aforementioned learning rules, successfully addressed two different tasks of unsupervised learning.
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3
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Hansel C. Contiguity in perception: origins in cellular associative computations. Trends Neurosci 2024; 47:170-180. [PMID: 38310022 PMCID: PMC10939850 DOI: 10.1016/j.tins.2024.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 11/30/2023] [Accepted: 01/05/2024] [Indexed: 02/05/2024]
Abstract
Our brains are good at detecting and learning associative structures; according to some linguistic theories, this capacity even constitutes a prerequisite for the development of syntax and compositionality in language and verbalized thought. I will argue that the search for associative motifs in input patterns is an evolutionary old brain function that enables contiguity in sensory perception and orientation in time and space. It has its origins in an elementary material property of cells that is particularly evident at chemical synapses: input-assigned calcium influx that activates calcium sensor proteins involved in memory storage. This machinery for the detection and learning of associative motifs generates knowledge about input relationships and integrates this knowledge into existing networks through updates in connectivity patterns.
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Affiliation(s)
- Christian Hansel
- Department of Neurobiology, University of Chicago, Chicago, IL 60637, USA.
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4
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Lara-González E, Padilla-Orozco M, Fuentes-Serrano A, Bargas J, Duhne M. Translational neuronal ensembles: Neuronal microcircuits in psychology, physiology, pharmacology and pathology. Front Syst Neurosci 2022; 16:979680. [PMID: 36090187 PMCID: PMC9449457 DOI: 10.3389/fnsys.2022.979680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 07/27/2022] [Indexed: 11/23/2022] Open
Abstract
Multi-recording techniques show evidence that neurons coordinate their firing forming ensembles and that brain networks are made by connections between ensembles. While “canonical” microcircuits are composed of interconnected principal neurons and interneurons, it is not clear how they participate in recorded neuronal ensembles: “groups of neurons that show spatiotemporal co-activation”. Understanding synapses and their plasticity has become complex, making hard to consider all details to fill the gap between cellular-synaptic and circuit levels. Therefore, two assumptions became necessary: First, whatever the nature of the synapses these may be simplified by “functional connections”. Second, whatever the mechanisms to achieve synaptic potentiation or depression, the resultant synaptic weights are relatively stable. Both assumptions have experimental basis cited in this review, and tools to analyze neuronal populations are being developed based on them. Microcircuitry processing followed with multi-recording techniques show temporal sequences of neuronal ensembles resembling computational routines. These sequences can be aligned with the steps of behavioral tasks and behavior can be modified upon their manipulation, supporting the hypothesis that they are memory traces. In vitro, recordings show that these temporal sequences can be contained in isolated tissue of histological scale. Sequences found in control conditions differ from those recorded in pathological tissue obtained from animal disease models and those recorded after the actions of clinically useful drugs to treat disease states, setting the basis for new bioassays to test drugs with potential clinical use. These findings make the neuronal ensembles theoretical framework a dynamic neuroscience paradigm.
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Affiliation(s)
- Esther Lara-González
- División Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Department of Neuroscience, Feinberg School of Medicine, Northwestern University, Chicago, IL, United States
| | - Montserrat Padilla-Orozco
- División Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Alejandra Fuentes-Serrano
- División Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - José Bargas
- División Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
- *Correspondence: José Bargas,
| | - Mariana Duhne
- División Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Department of Neurology, University of California, San Francisco, San Francisco, CA, United States
- Mariana Duhne,
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5
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Kumar MG, Tan C, Libedinsky C, Yen SC, Tan AYY. A Nonlinear Hidden Layer Enables Actor-Critic Agents to Learn Multiple Paired Association Navigation. Cereb Cortex 2022; 32:3917-3936. [PMID: 35034127 DOI: 10.1093/cercor/bhab456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 11/05/2021] [Accepted: 11/06/2021] [Indexed: 11/15/2022] Open
Abstract
Navigation to multiple cued reward locations has been increasingly used to study rodent learning. Though deep reinforcement learning agents have been shown to be able to learn the task, they are not biologically plausible. Biologically plausible classic actor-critic agents have been shown to learn to navigate to single reward locations, but which biologically plausible agents are able to learn multiple cue-reward location tasks has remained unclear. In this computational study, we show versions of classic agents that learn to navigate to a single reward location, and adapt to reward location displacement, but are not able to learn multiple paired association navigation. The limitation is overcome by an agent in which place cell and cue information are first processed by a feedforward nonlinear hidden layer with synapses to the actor and critic subject to temporal difference error-modulated plasticity. Faster learning is obtained when the feedforward layer is replaced by a recurrent reservoir network.
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Affiliation(s)
- M Ganesh Kumar
- Integrative Sciences and Engineering Programme, NUS Graduate School, National University of Singapore, Singapore 119077, Singapore
- The N.1 Institute for Health, National University of Singapore, Singapore 117456, Singapore
- Innovation and Design Programme, Faculty of Engineering, National University of Singapore, Singapore 117579, Singapore
| | - Cheston Tan
- Institute for Infocomm Research, Agency for Science, Technology and Research, Singapore 138632, Singapore
| | - Camilo Libedinsky
- Integrative Sciences and Engineering Programme, NUS Graduate School, National University of Singapore, Singapore 119077, Singapore
- The N.1 Institute for Health, National University of Singapore, Singapore 117456, Singapore
- Department of Psychology, National University of Singapore, Singapore 117570, Singapore
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Singapore 138673, Singapore
| | - Shih-Cheng Yen
- Integrative Sciences and Engineering Programme, NUS Graduate School, National University of Singapore, Singapore 119077, Singapore
- The N.1 Institute for Health, National University of Singapore, Singapore 117456, Singapore
- Innovation and Design Programme, Faculty of Engineering, National University of Singapore, Singapore 117579, Singapore
| | - Andrew Y Y Tan
- Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117593, Singapore
- Healthy Longevity Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
- Cardiovascular Disease Translational Research Programme, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
- Neurobiology Programme, Life Sciences Institute, National University of Singapore, Singapore 119077, Singapore
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6
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Roome CJ, Kuhn B. Dendritic coincidence detection in Purkinje neurons of awake mice. eLife 2020; 9:59619. [PMID: 33345779 PMCID: PMC7771959 DOI: 10.7554/elife.59619] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 12/18/2020] [Indexed: 12/19/2022] Open
Abstract
Dendritic coincidence detection is fundamental to neuronal processing yet remains largely unexplored in awake animals. Specifically, the underlying dendritic voltage–calcium relationship has not been directly addressed. Here, using simultaneous voltage and calcium two-photon imaging of Purkinje neuron spiny dendrites, we show how coincident synaptic inputs and resulting dendritic spikes modulate dendritic calcium signaling during sensory stimulation in awake mice. Sensory stimulation increased the rate of postsynaptic potentials and dendritic calcium spikes evoked by climbing fiber and parallel fiber synaptic input. These inputs are integrated in a time-dependent and nonlinear fashion to enhance the sensory-evoked dendritic calcium signal. Intrinsic supralinear dendritic mechanisms, including voltage-gated calcium channels and metabotropic glutamate receptors, are recruited cooperatively to expand the dynamic range of sensory-evoked dendritic calcium signals. This establishes how dendrites can use multiple interplaying mechanisms to perform coincidence detection, as a fundamental and ongoing feature of dendritic integration in behaving animals.
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Affiliation(s)
- Christopher J Roome
- Optical Neuroimaging Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Okinawa, Japan
| | - Bernd Kuhn
- Optical Neuroimaging Unit, Okinawa Institute of Science and Technology Graduate University (OIST), Okinawa, Japan
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7
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8
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Optical interrogation of multi-scale neuronal plasticity underlying behavioral learning. Curr Opin Neurobiol 2020; 67:8-15. [PMID: 32768886 DOI: 10.1016/j.conb.2020.07.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 07/14/2020] [Accepted: 07/17/2020] [Indexed: 01/16/2023]
Abstract
Behavioral learning is driven by adaptive changes in the activation of behaviorally relevant neuronal ensembles. This learning-specific reorganization of neuronal circuits is correlated with activity-dependent modifications of synaptic dynamics. However, a definitive causal link remains to be established. How is synaptic plasticity distributed among circuits to eventually shape behavioral learning? A multi-scale understanding of the progressive plasticity is hindered by the lack of techniques for monitoring and manipulating these events. The current rise of synaptic optogenetics, especially combined with brain-wide circuit imaging, opens an entirely new avenue for studying causality at multiple scales. In this review, we summarize these technical achievements and discuss challenges in linking the plasticity across levels to elucidate the multi-scale mechanisms of learning.
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Murray LM, Knikou M. Repeated cathodal transspinal pulse and direct current stimulation modulate cortical and corticospinal excitability differently in healthy humans. Exp Brain Res 2019; 237:1841-1852. [DOI: 10.1007/s00221-019-05559-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 05/08/2019] [Indexed: 10/26/2022]
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10
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Langille JJ. Remembering to Forget: A Dual Role for Sleep Oscillations in Memory Consolidation and Forgetting. Front Cell Neurosci 2019; 13:71. [PMID: 30930746 PMCID: PMC6425990 DOI: 10.3389/fncel.2019.00071] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 02/13/2019] [Indexed: 12/20/2022] Open
Abstract
It has been known since the time of patient H. M. and Karl Lashley's equipotentiality studies that the hippocampus and cortex serve mnestic functions. Current memory models maintain that these two brain structures accomplish unique, but interactive, memory functions. Specifically, most modeling suggests that memories are rapidly acquired during waking experience by the hippocampus, before being later consolidated into the cortex for long-term storage. Sleep has been shown to be critical for the transfer and consolidation of memories in the cortex. Like memory consolidation, a role for sleep in adaptive forgetting has both historical precedent, as Francis Crick suggested in 1983 that sleep was for "reverse-learning," and recent empirical support. In this article I review the evidence indicating that the same brain activity involved in sleep replay associated memory consolidation is responsible for sleep-dependent forgetting. In reviewing the literature, it became clear that both a cellular mechanism for systems consolidation and an agreed upon general, as well as cellular, mechanism for sleep-dependent forgetting is seldom discussed or is lacking. I advocate here for a candidate cellular systems consolidation mechanism wherein changes in calcium kinetics and the activation of consolidative signaling cascades arise from the triple phase locking of non-rapid eye movement sleep (NREMS) slow oscillation, sleep spindle and sharp-wave ripple rhythms. I go on to speculatively consider several sleep stage specific forgetting mechanisms and conclude by discussing a notional function of NREM-rapid eye movement sleep (REMS) cycling. The discussed model argues that the cyclical organization of sleep functions to first lay down and edit and then stabilize and integrate engrams. All things considered, it is increasingly clear that hallmark sleep stage rhythms, including several NREMS oscillations and the REMS hippocampal theta rhythm, serve the dual function of enabling simultaneous memory consolidation and adaptive forgetting. Specifically, the same sleep rhythms that consolidate new memories, in the cortex and hippocampus, simultaneously organize the adaptive forgetting of older memories in these brain regions.
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Affiliation(s)
- Jesse J Langille
- Department of Neurology and Neurosurgery, McGill University, Montreal, QC, Canada
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11
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Espinosa-Ramos JI, Capecci E, Kasabov N. A Computational Model of Neuroreceptor-Dependent Plasticity (NRDP) Based on Spiking Neural Networks. IEEE Trans Cogn Dev Syst 2019. [DOI: 10.1109/tcds.2017.2776863] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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12
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Abstract
The climbing fiber-Purkinje cell circuit is one of the most powerful and highly conserved in the central nervous system. Climbing fibers exert a powerful excitatory action that results in a complex spike in Purkinje cells and normal functioning of the cerebellum depends on the integrity of climbing fiber-Purkinje cell synapse. Over the last 50 years, multiple hypotheses have been put forward on the role of the climbing fibers and complex spikes in cerebellar information processing and motor control. Central to these theories is the nature of the interaction between the low-frequency complex spike discharge and the high-frequency simple spike firing of Purkinje cells. This review examines the major hypotheses surrounding the action of the climbing fiber-Purkinje cell projection, discussing both supporting and conflicting findings. The review describes newer findings establishing that climbing fibers and complex spikes provide predictive signals about movement parameters and that climbing fiber input controls the encoding of behavioral information in the simple spike firing of Purkinje cells. Finally, we propose the dynamic encoding hypothesis for complex spike function that strives to integrate established and newer findings.
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Affiliation(s)
- Martha L Streng
- Department of Neuroscience, University of Minnesota, Lions Research Building, Room 421, 2001 Sixth Street S.E, Minneapolis, MN, 55455, USA
| | - Laurentiu S Popa
- Department of Neuroscience, University of Minnesota, Lions Research Building, Room 421, 2001 Sixth Street S.E, Minneapolis, MN, 55455, USA
| | - Timothy J Ebner
- Department of Neuroscience, University of Minnesota, Lions Research Building, Room 421, 2001 Sixth Street S.E, Minneapolis, MN, 55455, USA.
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13
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Langille JJ, Brown RE. The Synaptic Theory of Memory: A Historical Survey and Reconciliation of Recent Opposition. Front Syst Neurosci 2018; 12:52. [PMID: 30416432 PMCID: PMC6212519 DOI: 10.3389/fnsys.2018.00052] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Accepted: 09/28/2018] [Indexed: 01/12/2023] Open
Abstract
Trettenbrein (2016) has argued that the concept of the synapse as the locus of memory is outdated and has made six critiques of this concept. In this article, we examine these six critiques and suggest that the current theories of the neurobiology of memory and the empirical data indicate that synaptic activation is the first step in a chain of cellular and biochemical events that lead to memories formed in cell assemblies and neural networks that rely on synaptic modification for their formation. These neural networks and their modified synaptic connections can account for the cognitive basis of learning and memory and for memory deterioration in neurological disorders. We first discuss Hebb's (1949) theory that synaptic change and the formation of cell assemblies and phase sequences can link neurophysiology to cognitive processes. We then examine each of Trettenbrein's (2016) critiques of the synaptic theory in light of Hebb's theories and recent empirical data. We examine the biochemical basis of memory formation and the necessity of synaptic modification to form the neural networks underlying learning and memory. We then examine the use of Hebb's theories of synaptic change and cell assemblies for integrating neurophysiological and cognitive conceptions of learning and memory. We conclude with an examination of the applications of the Hebb synapse and cell assembly theories to the study of the neuroscience of learning and memory, the development of computational models of memory and the construction of "intelligent" robots. We conclude that the synaptic theory of memory has not met its demise, but is essential to our understanding of the neural basis of memory, which has two components: synaptic plasticity and intrinsic plasticity.
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Affiliation(s)
| | - Richard E. Brown
- Department of Psychology and Neuroscience, Dalhousie University, Halifax, NS, Canada
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14
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Zhang Y, Magnus G, Han VZ. Cell type-specific plasticity at parallel fiber synapses onto Purkinje cells in the posterior caudal lobe of the mormyrid fish cerebellum. J Neurophysiol 2018; 120:644-661. [PMID: 29668384 DOI: 10.1152/jn.00175.2018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
It has been demonstrated that there are two morphological subtypes of Purkinje cells (PCs)-fan-shaped Purkinje cells (fPCs) and multipolar Purkinje cells (mPCs)-in the posterior caudal lobe of the mormyrid fish cerebellum, but whether these cell types are also functionally distinct is unknown. Here, we have used electrophysiological and pharmacological tools in a slice preparation to demonstrate that pairing parallel fiber (PF) and climbing fiber (CF) inputs at a low frequency induces long-term depression (LTD) in fPCs but long-term potentiation (LTP) in mPCs. The induction of plasticity in both cell types required postsynaptic Ca2+ and type 1α metabotropic glutamate receptors. However, the LTD in fPCs was inducted via a calcium/calmodulin-dependent protein kinase II cascade, whereas LTP induction in mPCs required calcineurin. Moreover, the LTD in fPCs and LTP in mPCs were accompanied by changes to the corresponding paired-pulse ratios and their coefficients of variation, suggesting presynaptic modes of expression for the plasticity at PF terminals for both cell types. Hence, the synaptic plasticity at PF synapses onto PCs in the posterior caudal lobe of the mormyrid cerebellum is cell type specific, with both pre- and postsynaptic mechanisms contributing to its induction and expression. NEW & NOTEWORTHY Much has been learnt about the cerebellar long-term depression (LTD) in the cortex. More recent work has shown that long-term potentiation (LTP) is equally important for cerebellar motor learning. Here we report for the first time that plasticity in the mormyrid cerebellum is cell type specific, e.g., following the conventional pairing of parallel and climbing fiber inputs in an in vitro preparation leads to LTD in one Purkinje cell subtype and LTP in another.
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Affiliation(s)
- Yueping Zhang
- Department of Pediatrics and Neuroscience, Xijing Hospital , Xi'an , China.,Center for Integrative Brain Research, Seattle Children's Research Institute , Seattle, Washington
| | - Gerhard Magnus
- Center for Integrative Brain Research, Seattle Children's Research Institute , Seattle, Washington
| | - Victor Z Han
- Center for Integrative Brain Research, Seattle Children's Research Institute , Seattle, Washington
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15
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The Roles of the Olivocerebellar Pathway in Motor Learning and Motor Control. A Consensus Paper. THE CEREBELLUM 2017; 16:230-252. [PMID: 27193702 DOI: 10.1007/s12311-016-0787-8] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
For many decades, the predominant view in the cerebellar field has been that the olivocerebellar system's primary function is to induce plasticity in the cerebellar cortex, specifically, at the parallel fiber-Purkinje cell synapse. However, it has also long been proposed that the olivocerebellar system participates directly in motor control by helping to shape ongoing motor commands being issued by the cerebellum. Evidence consistent with both hypotheses exists; however, they are often investigated as mutually exclusive alternatives. In contrast, here, we take the perspective that the olivocerebellar system can contribute to both the motor learning and motor control functions of the cerebellum and might also play a role in development. We then consider the potential problems and benefits of it having multiple functions. Moreover, we discuss how its distinctive characteristics (e.g., low firing rates, synchronization, and variable complex spike waveforms) make it more or less suitable for one or the other of these functions, and why having multiple functions makes sense from an evolutionary perspective. We did not attempt to reach a consensus on the specific role(s) the olivocerebellar system plays in different types of movements, as that will ultimately be determined experimentally; however, collectively, the various contributions highlight the flexibility of the olivocerebellar system, and thereby suggest that it has the potential to act in both the motor learning and motor control functions of the cerebellum.
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16
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Hebbian Spike-Timing Dependent Plasticity at the Cerebellar Input Stage. J Neurosci 2017; 37:2809-2823. [PMID: 28188217 DOI: 10.1523/jneurosci.2079-16.2016] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2016] [Revised: 11/10/2016] [Accepted: 12/28/2016] [Indexed: 11/21/2022] Open
Abstract
Spike-timing-dependent plasticity (STDP) is a form of long-term synaptic plasticity exploiting the time relationship between postsynaptic action potentials (APs) and EPSPs. Surprisingly enough, very little was known about STDP in the cerebellum, although it is thought to play a critical role for learning appropriate timing of actions. We speculated that low-frequency oscillations observed in the granular layer may provide a reference for repetitive EPSP/AP phase coupling. Here we show that EPSP-spike pairing at 6 Hz can optimally induce STDP at the mossy fiber-granule cell synapse in rats. Spike timing-dependent long-term potentiation and depression (st-LTP and st-LTD) were confined to a ±25 ms time-window. Because EPSPs led APs in st-LTP while APs led EPSPs in st-LTD, STDP was Hebbian in nature. STDP occurred at 6-10 Hz but vanished >50 Hz or <1 Hz (where only LTP or LTD occurred). STDP disappeared with randomized EPSP/AP pairing or high intracellular Ca2+ buffering, and its sign was inverted by GABA-A receptor activation. Both st-LTP and st-LTD required NMDA receptors, but st-LTP also required reinforcing signals mediated by mGluRs and intracellular calcium stores. Importantly, st-LTP and st-LTD were significantly larger than LTP and LTD obtained by modulating the frequency and duration of mossy fiber bursts, probably because STDP expression involved postsynaptic in addition to presynaptic mechanisms. These results thus show that a Hebbian form of STDP occurs at the cerebellum input stage, providing the substrate for phase-dependent binding of mossy fiber spikes to repetitive theta-frequency cycles of granule cell activity.SIGNIFICANCE STATEMENT Long-term synaptic plasticity is a fundamental property of the brain, causing persistent modifications of neuronal communication thought to provide the cellular basis of learning and memory. The cerebellum is critical for learning the appropriate timing of sensorimotor behaviors, but whether and how appropriate spike patterns could drive long-term synaptic plasticity remained unknown. Here, we show that this can actually occur through a form of spike-timing-dependent plasticity (STDP) at the cerebellar inputs stage. Pairing presynaptic and postsynaptic spikes at 6-10 Hz reliably induced STDP at the mossy fiber-granule cell synapse, with potentiation and depression symmetrically distributed within a ±25 ms time window. Thus, STDP can bind plasticity to the mossy fiber burst phase with high temporal precision.
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17
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Climbing Fibers Control Purkinje Cell Representations of Behavior. J Neurosci 2017; 37:1997-2009. [PMID: 28077726 DOI: 10.1523/jneurosci.3163-16.2017] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Revised: 12/13/2016] [Accepted: 01/06/2017] [Indexed: 11/21/2022] Open
Abstract
A crucial issue in understanding cerebellar function is the interaction between simple spike (SS) and complex spike (CS) discharge, the two fundamentally different activity modalities of Purkinje cells. Although several hypotheses have provided insights into the interaction, none fully explains or is completely consistent with the spectrum of experimental observations. Here, we show that during a pseudo-random manual tracking task in the monkey (Macaca mulatta), climbing fiber discharge dynamically controls the information present in the SS firing, triggering robust and rapid changes in the SS encoding of motor signals in 67% of Purkinje cells. The changes in encoding, tightly coupled to CS occurrences, consist of either increases or decreases in the SS sensitivity to kinematics or position errors and are not due to differences in SS firing rates or variability. Nor are the changes in sensitivity due to CS rhythmicity. In addition, the CS-coupled changes in encoding are not evoked by changes in kinematics or position errors. Instead, CS discharge most often leads alterations in behavior. Increases in SS encoding of a kinematic parameter are associated with larger changes in that parameter than are decreases in SS encoding. Increases in SS encoding of position error are followed by and scale with decreases in error. The results suggest a novel function of CSs, in which climbing fiber input dynamically controls the state of Purkinje cell SS encoding in advance of changes in behavior.SIGNIFICANCE STATEMENT Purkinje cells, the sole output of the cerebellar cortex, manifest two fundamentally different activity modalities, complex spike (CS) discharge and simple spike (SS) firing. Elucidating cerebellar function will require an understanding of the interactions, both short- and long-term, between CS and SS firing. This study shows that CSs dynamically control the information encoded in a Purkinje cell's SS activity by rapidly increasing or decreasing the SS sensitivity to kinematics and/or performance errors independent of firing rate. In many cases, the CS-coupled shift in SS encoding leads a change in behavior. These novel findings on the interaction between CS and SS firing provide for a new hypothesis in which climbing fiber input adjusts the encoding of SS information in advance of a change in behavior.
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18
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Calcium threshold shift enables frequency-independent control of plasticity by an instructive signal. Proc Natl Acad Sci U S A 2016; 113:13221-13226. [PMID: 27799554 DOI: 10.1073/pnas.1613897113] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
At glutamatergic synapses, both long-term potentiation (LTP) and long-term depression (LTD) can be induced at the same synaptic activation frequency. Instructive signals determine whether LTP or LTD is induced, by modulating local calcium transients. Synapses maintain the ability to potentiate or depress over a wide frequency range, but it remains unknown how calcium-controlled plasticity operates when frequency variations alone cause differences in calcium amplitudes. We addressed this problem at cerebellar parallel fiber-Purkinje cell synapses, which can undergo LTD or LTP in response to 1-Hz and 100-Hz stimulation. We observed that high-frequency activation elicits larger spine calcium transients than low-frequency stimulation under all stimulus conditions, but, regardless of activation frequency, climbing fiber (CF) coactivation provides an instructive signal that further enhances calcium transients and promotes LTD. At both frequencies, buffering calcium prevents LTD induction and LTP results instead, identifying the enhanced calcium signal amplitude as the critical parameter contributed by the instructive CF signal. These observations show that it is not absolute calcium amplitudes that determine whether LTD or LTP is evoked but, instead, the LTD threshold slides, thus preserving the requirement for relatively larger calcium transients for LTD than for LTP induction at any given stimulus frequency. Cerebellar LTD depends on the activation of calcium/calmodulin-dependent kinase II (CaMKII). Using genetically modified (TT305/6VA and T305D) mice, we identified α-CaMKII inhibition upon autophosphorylation at Thr305/306 as a molecular event underlying the threshold shift. This mechanism enables frequency-independent plasticity control by the instructive CF signal based on relative, not absolute, calcium thresholds.
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Abstract
Synaptic plasticity at the parallel fiber to Purkinje cell synapse has long been considered a cellular correlate for cerebellar motor learning. Functionally, long-term depression and long-term potentiation at these synapses seem to be the reverse of each other, with both pre- and post-synaptic expression occurring in both. However, different cerebellar motor learning paradigms have been shown to be asymmetric and not equally reversible. Here, we discuss the asymmetric reversibility shown in the vestibulo-ocular reflex and eyeblink conditioning and suggest that different cellular plasticity mechanisms might be recruited under different conditions leading to unequal reversibility.
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Affiliation(s)
- Heather K Titley
- Department of Neurobiology, University of Chicago, Chicago, IL, 60637, USA.
| | - Christian Hansel
- Department of Neurobiology, University of Chicago, Chicago, IL, 60637, USA
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20
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Grasselli G, He Q, Wan V, Adelman JP, Ohtsuki G, Hansel C. Activity-Dependent Plasticity of Spike Pauses in Cerebellar Purkinje Cells. Cell Rep 2016; 14:2546-53. [PMID: 26972012 PMCID: PMC4805497 DOI: 10.1016/j.celrep.2016.02.054] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 01/04/2016] [Accepted: 02/08/2016] [Indexed: 12/13/2022] Open
Abstract
The plasticity of intrinsic excitability has been described in several types of neurons, but the significance of non-synaptic mechanisms in brain plasticity and learning remains elusive. Cerebellar Purkinje cells are inhibitory neurons that spontaneously fire action potentials at high frequencies and regulate activity in their target cells in the cerebellar nuclei by generating a characteristic spike burst-pause sequence upon synaptic activation. Using patch-clamp recordings from mouse Purkinje cells, we find that depolarization-triggered intrinsic plasticity enhances spike firing and shortens the duration of spike pauses. Pause plasticity is absent from mice lacking SK2-type potassium channels (SK2(-/-) mice) and in occlusion experiments using the SK channel blocker apamin, while apamin wash-in mimics pause reduction. Our findings demonstrate that spike pauses can be regulated through an activity-dependent, exclusively non-synaptic, SK2 channel-dependent mechanism and suggest that pause plasticity-by altering the Purkinje cell output-may be crucial to cerebellar information storage and learning.
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Affiliation(s)
- Giorgio Grasselli
- Department of Neurobiology, University of Chicago, Chicago, IL 60637, USA
| | - Qionger He
- Department of Neurobiology, University of Chicago, Chicago, IL 60637, USA
| | - Vivian Wan
- Department of Neurobiology, University of Chicago, Chicago, IL 60637, USA
| | - John P Adelman
- Vollum Institute, Oregon Health & Science University, Portland, OR 97239, USA
| | - Gen Ohtsuki
- Department of Biophysics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan; The Habuki Center, Kyoto University, Kyoto 606-8302, Japan
| | - Christian Hansel
- Department of Neurobiology, University of Chicago, Chicago, IL 60637, USA.
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Wu C, Martel DT, Shore SE. Transcutaneous induction of stimulus-timing-dependent plasticity in dorsal cochlear nucleus. Front Syst Neurosci 2015; 9:116. [PMID: 26321928 PMCID: PMC4536405 DOI: 10.3389/fnsys.2015.00116] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 07/30/2015] [Indexed: 11/13/2022] Open
Abstract
The cochlear nucleus (CN) is the first site of multisensory integration in the ascending auditory pathway. The principal output neurons of the dorsal cochlear nucleus (DCN), fusiform cells, receive somatosensory information relayed by the CN granule cells from the trigeminal and dorsal column pathways. Integration of somatosensory and auditory inputs results in long-term enhancement or suppression in a stimulus-timing-dependent manner. Here, we demonstrate that stimulus-timing-dependent plasticity (STDP) can be induced in DCN fusiform cells using paired auditory and transcutaneous electrical stimulation of the face and neck to activate trigeminal and dorsal column pathways to the CN, respectively. Long-lasting changes in fusiform cell firing rates persisted for up to 2 h after this bimodal stimulation, and followed Hebbian or anti-Hebbian rules, depending on tone duration, but not somatosensory stimulation location: 50 ms paired tones evoked predominantly Hebbian, while 10 ms paired tones evoked predominantly anti-Hebbian plasticity. The tone-duration-dependent STDP was strongly correlated with first inter-spike intervals, implicating intrinsic cellular properties as determinants of STDP. This study demonstrates that transcutaneous stimulation with precise auditory-somatosensory timing parameters can non-invasively induce fusiform cell long-term modulation, which could be harnessed in the future to moderate tinnitus-related hyperactivity in DCN.
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Affiliation(s)
- Calvin Wu
- Kresge Hearing Research Institute-Department of Otolaryngology, University of Michigan Ann Arbor, MI, USA
| | - David T Martel
- Kresge Hearing Research Institute-Department of Otolaryngology, University of Michigan Ann Arbor, MI, USA ; Department of Biomedical Engineering, University of Michigan Ann Arbor, MI, USA
| | - Susan E Shore
- Kresge Hearing Research Institute-Department of Otolaryngology, University of Michigan Ann Arbor, MI, USA ; Department of Biomedical Engineering, University of Michigan Ann Arbor, MI, USA ; Department of Molecular and Integrative Physiology, University of Michigan Ann Arbor, MI, USA
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22
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Knikou M, Dixon L, Santora D, Ibrahim MM. Transspinal constant-current long-lasting stimulation: a new method to induce cortical and corticospinal plasticity. J Neurophysiol 2015; 114:1486-99. [PMID: 26108955 DOI: 10.1152/jn.00449.2015] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Accepted: 06/23/2015] [Indexed: 11/22/2022] Open
Abstract
Functional neuroplasticity in response to stimulation and motor training is a well-established phenomenon. Transcutaneous stimulation of the spine is used mostly to alleviate pain, but it may also induce functional neuroplasticity, because the spinal cord serves as an integration center for descending and ascending neuronal signals. In this work, we examined whether long-lasting noninvasive cathodal (c-tsCCS) and anodal (a-tsCCS) transspinal constant-current stimulation over the thoracolumbar enlargement can induce cortical, corticospinal, and spinal neuroplasticity. Twelve healthy human subjects, blind to the stimulation protocol, were randomly assigned to 40 min of c-tsCCS or a-tsCCS. Before and after transspinal stimulation, we established the afferent-mediated motor evoked potential (MEP) facilitation and the subthreshold transcranial magnetic stimulation (TMS)-mediated flexor reflex facilitation. Recruitment input-output curves of MEPs and transspinal evoked potentials (TEPs) and postactivation depression of the soleus H reflex and TEPs was also established. We demonstrate that both c-tsCCS and a-tsCCS decrease the afferent-mediated MEP facilitation and alter the subthreshold TMS-mediated flexor reflex facilitation in a polarity-dependent manner. Both c-tsCCS and a-tsCCS increased the tibialis anterior MEPs recorded at 1.2 MEP resting threshold, intermediate, and maximal intensities and altered the recruitment input-output curve of TEPs in a muscle- and polarity-dependent manner. Soleus H-reflex postactivation depression was reduced after a-tsCCS and remained unaltered after c-tsCCS. No changes were found in the postactivation depression of TEPs after c-tsCCS or a-tsCCS. Our findings reveal that c-tsCCS and a-tsCCS have distinct effects on cortical and corticospinal excitability. This method can be utilized to induce targeted neuroplasticity in humans.
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Affiliation(s)
- Maria Knikou
- The Graduate Center, City University of New York, New York, New York; and Department of Physical Therapy, City University of New York, New York, New York
| | - Luke Dixon
- Department of Physical Therapy, City University of New York, New York, New York
| | - Danielle Santora
- Department of Physical Therapy, City University of New York, New York, New York
| | - Mohamed M Ibrahim
- Department of Physical Therapy, City University of New York, New York, New York
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Cheron G, Márquez-Ruiz J, Kishino T, Dan B. Disruption of the LTD dialogue between the cerebellum and the cortex in Angelman syndrome model: a timing hypothesis. Front Syst Neurosci 2014; 8:221. [PMID: 25477791 PMCID: PMC4237040 DOI: 10.3389/fnsys.2014.00221] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 10/25/2014] [Indexed: 12/11/2022] Open
Abstract
Angelman syndrome (AS) is a genetic neurodevelopmental disorder in which cerebellar functioning impairment has been documented despite the absence of gross structural abnormalities. Characteristically, a spontaneous 160 Hz oscillation emerges in the Purkinje cells network of the Ube3a (m-/p+) Angelman mouse model. This abnormal oscillation is induced by enhanced Purkinje cell rhythmicity and hypersynchrony along the parallel fiber beam. We present a pathophysiological hypothesis for the neurophysiology underlying major aspects of the clinical phenotype of AS, including cognitive, language and motor deficits, involving long-range connection between the cerebellar and the cortical networks. This hypothesis states that the alteration of the cerebellar rhythmic activity impinges cerebellar long-term depression (LTD) plasticity, which in turn alters the LTD plasticity in the cerebral cortex. This hypothesis was based on preliminary experiments using electrical stimulation of the whiskers pad performed in alert mice showing that after a 8 Hz LTD-inducing protocol, the cerebellar LTD accompanied by a delayed response in the wild type (WT) mice is missing in Ube3a (m-/p+) mice and that the LTD induced in the barrel cortex following the same peripheral stimulation in wild mice is reversed into a LTP in the Ube3a (m-/p+) mice. The control exerted by the cerebellum on the excitation vs. inhibition balance in the cerebral cortex and possible role played by the timing plasticity of the Purkinje cell LTD on the spike-timing dependent plasticity (STDP) of the pyramidal neurons are discussed in the context of the present hypothesis.
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Affiliation(s)
- Guy Cheron
- Laboratory of Electrophysiology, Université de MonsMons, Belgium
- Laboratory of Neurophysiology and Movement Biomechanics, ULB Neuroscience Institut, Université Libre de BruxellesBrussels, Belgium
| | | | - Tatsuya Kishino
- Division of Functional Genomics, Center for Frontier Life Sciences, Nagasaki UniversityNagasaki, Japan
| | - Bernard Dan
- Department of Neurology, Hôpital Universitaire des Enfants Reine Fabiola, Université Libre de BruxellesBrussels, Belgium
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Najafi F, Giovannucci A, Wang SSH, Medina JF. Coding of stimulus strength via analog calcium signals in Purkinje cell dendrites of awake mice. eLife 2014; 3:e03663. [PMID: 25205669 PMCID: PMC4158287 DOI: 10.7554/elife.03663] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The climbing fiber input to Purkinje cells acts as a teaching signal by triggering a massive influx of dendritic calcium that marks the occurrence of instructive stimuli during cerebellar learning. Here, we challenge the view that these calcium spikes are all-or-none and only signal whether the instructive stimulus has occurred, without providing parametric information about its features. We imaged ensembles of Purkinje cell dendrites in awake mice and measured their calcium responses to periocular airpuffs that serve as instructive stimuli during cerebellar-dependent eyeblink conditioning. Information about airpuff duration and pressure was encoded probabilistically across repeated trials, and in two additional signals in single trials: the synchrony of calcium spikes in the Purkinje cell population, and the amplitude of the calcium spikes, which was modulated by a non-climbing fiber pathway. These results indicate that calcium-based teaching signals in Purkinje cells contain analog information that encodes the strength of instructive stimuli trial-by-trial. DOI:http://dx.doi.org/10.7554/eLife.03663.001 A region of the brain known as the cerebellum plays a key role in learning how to anticipate an event. For example, if you know that a puff of air is going to be directed at your eye, it's a good idea to close it in advance. However, how much you need to close it depends on how strong that puff of air is. A very strong puff might require closing the eye completely to protect it. In contrast, it is probably better to only partially close the eye if you know a lighter puff of air is coming, so that you can still see. Extensive research has focused on how neurons in and around the cerebellum work together to achieve this goal. When an event—such as a puff of air—occurs, signals are sent to large neurons in the cerebellum, called Purkinje cells, by ‘climbing fibers’. However, climbing fibers were thought to be able to respond in only two ways: either they fire in a single burst to signal that an event has occurred, or they don't fire. It was therefore unclear how the finer details of the event (for example, the strength of the puff of air) are transmitted to the cerebellum. Najafi et al. imaged the level of calcium in the cerebellum of mice, as this indicates how active the neurons are. When a puff of air was directed at the eyes of the mice, Najafi et al. saw that the size of the response of the Purkinje cells corresponded with how big the puff of air was. Najafi et al. show that the size of this response, which is based mostly on input from the climbing fibers, is also influenced by input from an additional unknown source. These findings show that Purkinje cells of the cerebellum receive detailed information about the nature of an event, such as a puff of air. What remains to be seen is whether the cerebellum uses this information to learn the correct response, that is how hard to blink to avoid the expected puff. DOI:http://dx.doi.org/10.7554/eLife.03663.002
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Affiliation(s)
- Farzaneh Najafi
- Department of Biology, University of Pennsylvania, Philadelphia, United States
| | - Andrea Giovannucci
- Department of Molecular Biology, Princeton University, Princeton, United States Princeton Neuroscience Institute, Princeton University, Princeton, United States
| | - Samuel S-H Wang
- Department of Molecular Biology, Princeton University, Princeton, United States Princeton Neuroscience Institute, Princeton University, Princeton, United States
| | - Javier F Medina
- Department of Psychology, University of Pennsylvania, Philadelphia, United States
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