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Zhu S, Xie T, Lv Z, Leng YB, Zhang YQ, Xu R, Qin J, Zhou Y, Roy VAL, Han ST. Hierarchies in Visual Pathway: Functions and Inspired Artificial Vision. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2301986. [PMID: 37435995 DOI: 10.1002/adma.202301986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 06/28/2023] [Accepted: 07/10/2023] [Indexed: 07/13/2023]
Abstract
The development of artificial intelligence has posed a challenge to machine vision based on conventional complementary metal-oxide semiconductor (CMOS) circuits owing to its high latency and inefficient power consumption originating from the data shuffling between memory and computation units. Gaining more insights into the function of every part of the visual pathway for visual perception can bring the capabilities of machine vision in terms of robustness and generality. Hardware acceleration of more energy-efficient and biorealistic artificial vision highly necessitates neuromorphic devices and circuits that are able to mimic the function of each part of the visual pathway. In this paper, we review the structure and function of the entire class of visual neurons from the retina to the primate visual cortex within reach (Chapter 2) are reviewed. Based on the extraction of biological principles, the recent hardware-implemented visual neurons located in different parts of the visual pathway are discussed in detail in Chapters 3 and 4. Furthermore, valuable applications of inspired artificial vision in different scenarios (Chapter 5) are provided. The functional description of the visual pathway and its inspired neuromorphic devices/circuits are expected to provide valuable insights for the design of next-generation artificial visual perception systems.
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Affiliation(s)
- Shirui Zhu
- Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Tao Xie
- Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Ziyu Lv
- College of Electronics and Information Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Yan-Bing Leng
- Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Yu-Qi Zhang
- Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Runze Xu
- Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Jingrun Qin
- Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Ye Zhou
- Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Vellaisamy A L Roy
- School of Science and Technology, Hong Kong Metropolitan University, Hong Kong, 999077, P. R. China
| | - Su-Ting Han
- College of Electronics and Information Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
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2
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Chen H, Li H, Ma T, Han S, Zhao Q. Biological function simulation in neuromorphic devices: from synapse and neuron to behavior. SCIENCE AND TECHNOLOGY OF ADVANCED MATERIALS 2023; 24:2183712. [PMID: 36926202 PMCID: PMC10013381 DOI: 10.1080/14686996.2023.2183712] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Revised: 02/06/2023] [Accepted: 02/11/2023] [Indexed: 06/18/2023]
Abstract
As the boom of data storage and processing, brain-inspired computing provides an effective approach to solve the current problem. Various emerging materials and devices have been reported to promote the development of neuromorphic computing. Thereinto, the neuromorphic device represented by memristor has attracted extensive research due to its outstanding property to emulate the brain's functions from synaptic plasticity, sensory-memory neurons to some intelligent behaviors of living creatures. Herein, we mainly review the progress of these brain functions mimicked by neuromorphic devices, concentrating on synapse (i.e. various synaptic plasticity trigger by electricity and/or light), neurons (including the various sensory nervous system) and intelligent behaviors (such as conditioned reflex represented by Pavlov's dog experiment). Finally, some challenges and prospects related to neuromorphic devices are presented.
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Affiliation(s)
- Hui Chen
- Heart Center of Henan Provincial People’s Hospital, Central China Fuwai Hospital, Central China Fuwai Hospital of Zhengzhou University, Zhengzhou, P. R. China
| | - Huilin Li
- Henan Key Laboratory of Photovoltaic Materials, Henan University, Kaifeng, P. R. China
| | - Ting Ma
- Henan Key Laboratory of Photovoltaic Materials, Henan University, Kaifeng, P. R. China
| | - Shuangshuang Han
- Henan Key Laboratory of Photovoltaic Materials, Henan University, Kaifeng, P. R. China
| | - Qiuping Zhao
- Heart Center of Henan Provincial People’s Hospital, Central China Fuwai Hospital, Central China Fuwai Hospital of Zhengzhou University, Zhengzhou, P. R. China
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3
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Sarwat SG, Kersting B, Moraitis T, Jonnalagadda VP, Sebastian A. Phase-change memtransistive synapses for mixed-plasticity neural computations. NATURE NANOTECHNOLOGY 2022; 17:507-513. [PMID: 35347271 DOI: 10.1038/s41565-022-01095-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Accepted: 01/12/2022] [Indexed: 06/14/2023]
Abstract
In the mammalian nervous system, various synaptic plasticity rules act, either individually or synergistically, over wide-ranging timescales to enable learning and memory formation. Hence, in neuromorphic computing platforms, there is a significant need for artificial synapses that can faithfully express such multi-timescale plasticity mechanisms. Although some plasticity rules have been emulated with elaborate complementary metal oxide semiconductor and memristive circuitry, device-level hardware realizations of long-term and short-term plasticity with tunable dynamics are lacking. Here we introduce a phase-change memtransistive synapse that leverages both the non-volatility of the phase configurations and the volatility of field-effect modulation for implementing tunable plasticities. We show that these mixed-plasticity synapses can enable plasticity rules such as short-term spike-timing-dependent plasticity that helps with the modelling of dynamic environments. Further, we demonstrate the efficacy of the memtransistive synapses in realizing accelerators for Hopfield neural networks for solving combinatorial optimization problems.
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4
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Dong A, He K, Dudok B, Farrell JS, Guan W, Liput DJ, Puhl HL, Cai R, Wang H, Duan J, Albarran E, Ding J, Lovinger DM, Li B, Soltesz I, Li Y. A fluorescent sensor for spatiotemporally resolved imaging of endocannabinoid dynamics in vivo. Nat Biotechnol 2022; 40:787-798. [PMID: 34764491 PMCID: PMC9091059 DOI: 10.1038/s41587-021-01074-4] [Citation(s) in RCA: 77] [Impact Index Per Article: 38.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 08/27/2021] [Indexed: 12/13/2022]
Abstract
Endocannabinoids (eCBs) are retrograde neuromodulators with important functions in a wide range of physiological processes, but their in vivo dynamics remain largely uncharacterized. Here we developed a genetically encoded eCB sensor called GRABeCB2.0. GRABeCB2.0 consists of a circular-permutated EGFP and the human CB1 cannabinoid receptor, providing cell membrane trafficking, second-resolution kinetics with high specificity for eCBs, and shows a robust fluorescence response at physiological eCB concentrations. Using GRABeCB2.0, we monitored evoked and spontaneous changes in eCB dynamics in cultured neurons and acute brain slices. We observed spontaneous compartmentalized eCB transients in cultured neurons and eCB transients from single axonal boutons in acute brain slices, suggesting constrained, localized eCB signaling. When GRABeCB2.0 was expressed in the mouse brain, we observed foot shock-elicited and running-triggered eCB signaling in the basolateral amygdala and hippocampus, respectively. In a mouse model of epilepsy, we observed a spreading wave of eCB release that followed a Ca2+ wave through the hippocampus. GRABeCB2.0 is a robust probe for eCB release in vivo.
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Affiliation(s)
- Ao Dong
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Kaikai He
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
| | - Barna Dudok
- Department of Neurosurgery, Stanford University, Palo Alto, CA, USA
| | - Jordan S Farrell
- Department of Neurosurgery, Stanford University, Palo Alto, CA, USA
| | - Wuqiang Guan
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - Daniel J Liput
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA
- Laboratory of Molecular Physiology, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA
| | - Henry L Puhl
- Laboratory of Molecular Physiology, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA
| | - Ruyi Cai
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
| | - Huan Wang
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
| | - Jiali Duan
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China
| | - Eddy Albarran
- Neuroscience PhD Program, Stanford University, Palo Alto, CA, USA
| | - Jun Ding
- Department of Neurosurgery, Department of Neurology, Stanford University School of Medicine, Palo Alto, CA, USA
| | - David M Lovinger
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, USA
| | - Bo Li
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY, USA
| | - Ivan Soltesz
- Department of Neurosurgery, Stanford University, Palo Alto, CA, USA
| | - Yulong Li
- State Key Laboratory of Membrane Biology, Peking University School of Life Sciences, Beijing, China.
- PKU-IDG/McGovern Institute for Brain Research, Beijing, China.
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China.
- Chinese Institute for Brain Research, Beijing, China.
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5
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Climbing Fiber-Mediated Spillover Transmission to Interneurons Is Regulated by EAAT4. J Neurosci 2021; 41:8126-8133. [PMID: 34400517 DOI: 10.1523/jneurosci.0616-21.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 06/21/2021] [Accepted: 07/24/2021] [Indexed: 11/21/2022] Open
Abstract
Neurotransmitter spillover is a form of communication not readily predicted by anatomic structure. In the cerebellum, glutamate spillover from climbing fibers recruits molecular layer interneurons in the absence of conventional synaptic connections. Spillover-mediated signaling is typically limited by transporters that bind and reuptake glutamate. Here, we show that patterned expression of the excitatory amino acid transporter 4 (EAAT4) in Purkinje cells regulates glutamate spillover to molecular layer interneurons. Using male and female Aldolase C-Venus knock-in mice to visualize zebrin microzones, we find larger climbing fiber-evoked spillover EPSCs in regions with low levels of EAAT4 compared with regions with high EAAT4. This difference is not explained by presynaptic glutamate release properties or postsynaptic receptor density but rather by differences in the glutamate concentration reaching receptors on interneurons. Inhibiting glutamate transport normalizes the differences between microzones, suggesting that heterogeneity in EAAT4 expression is a primary determinant of differential spillover. These results show that neuronal glutamate transporters limit extrasynaptic transmission in a non-cell-autonomous manner and provide new insight into the functional specialization of cerebellar microzones.SIGNIFICANCE STATEMENT Excitatory amino acid transporters (EAATs) help maintain the fidelity and independence of point-to-point synaptic transmission. Whereas glial transporters are critical to maintain low ambient levels of extracellular glutamate to prevent excitotoxicity, neuronal transporters have more subtle roles in shaping excitatory synaptic transmission. Here we show that the patterned expression of neuronal EAAT4 in cerebellar microzones controls glutamate spillover from cerebellar climbing fibers to nearby interneurons. These results contribute to fundamental understanding of neuronal transporter functions and specialization of cerebellar microzones.
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6
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Yang JQ, Wang R, Ren Y, Mao JY, Wang ZP, Zhou Y, Han ST. Neuromorphic Engineering: From Biological to Spike-Based Hardware Nervous Systems. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2003610. [PMID: 33165986 DOI: 10.1002/adma.202003610] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 07/27/2020] [Indexed: 06/11/2023]
Abstract
The human brain is a sophisticated, high-performance biocomputer that processes multiple complex tasks in parallel with high efficiency and remarkably low power consumption. Scientists have long been pursuing an artificial intelligence (AI) that can rival the human brain. Spiking neural networks based on neuromorphic computing platforms simulate the architecture and information processing of the intelligent brain, providing new insights for building AIs. The rapid development of materials engineering, device physics, chip integration, and neuroscience has led to exciting progress in neuromorphic computing with the goal of overcoming the von Neumann bottleneck. Herein, fundamental knowledge related to the structures and working principles of neurons and synapses of the biological nervous system is reviewed. An overview is then provided on the development of neuromorphic hardware systems, from artificial synapses and neurons to spike-based neuromorphic computing platforms. It is hoped that this review will shed new light on the evolution of brain-like computing.
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Affiliation(s)
- Jia-Qin Yang
- College of Electronics and Information Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
- Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Ruopeng Wang
- College of Electronics and Information Engineering, Shenzhen University, Shenzhen, 518060, P. R. China
- Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Yi Ren
- Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Jing-Yu Mao
- Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Zhan-Peng Wang
- Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Ye Zhou
- Institute for Advanced Study, Shenzhen University, Shenzhen, 518060, P. R. China
| | - Su-Ting Han
- Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen, 518060, P. R. China
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7
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Albergaria C, Silva NT, Darmohray DM, Carey MR. Cannabinoids modulate associative cerebellar learning via alterations in behavioral state. eLife 2020; 9:61821. [PMID: 33077026 PMCID: PMC7575324 DOI: 10.7554/elife.61821] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 10/01/2020] [Indexed: 02/06/2023] Open
Abstract
Cannabinoids are notorious and profound modulators of behavioral state. In the brain, endocannabinoids act via Type 1-cannabinoid receptors (CB1) to modulate synaptic transmission and mediate multiple forms of synaptic plasticity. CB1 knockout (CB1KO) mice display a range of behavioral phenotypes, in particular hypoactivity and various deficits in learning and memory, including cerebellum-dependent delay eyeblink conditioning. Here we find that the apparent effects of CB1 deletion on cerebellar learning are not due to direct effects on CB1-dependent plasticity, but rather, arise as a secondary consequence of altered behavioral state. Hypoactivity of CB1KO mice accounts for their impaired eyeblink conditioning across both animals and trials. Moreover, learning in these mutants is rescued by walking on a motorized treadmill during training. Finally, cerebellar granule-cell-specific CB1KOs exhibit normal eyeblink conditioning, and both global and granule-cell-specific CB1KOs display normal cerebellum-dependent locomotor coordination and learning. These findings highlight the modulation of behavioral state as a powerful independent means through which individual genes contribute to complex behaviors.
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Affiliation(s)
- Catarina Albergaria
- Champalimaud Neuroscience Program, Champalimaud Center for the Unknown, Lisbon, Portugal
| | - N Tatiana Silva
- Champalimaud Neuroscience Program, Champalimaud Center for the Unknown, Lisbon, Portugal
| | - Dana M Darmohray
- Champalimaud Neuroscience Program, Champalimaud Center for the Unknown, Lisbon, Portugal
| | - Megan R Carey
- Champalimaud Neuroscience Program, Champalimaud Center for the Unknown, Lisbon, Portugal
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8
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Canepari M. Is Purkinje Neuron Hyperpolarisation Important for Cerebellar Synaptic Plasticity? A Retrospective and Prospective Analysis. THE CEREBELLUM 2020; 19:869-878. [PMID: 32654026 DOI: 10.1007/s12311-020-01164-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Two recent studies have demonstrated that the dendritic Ca2+ signal associated with a climbing fibre (CF) input to the cerebellar Purkinje neuron (PN) depends on the membrane potential (Vm). Specifically, when the cell is hyperpolarised, this signal is mediated by T-type voltage-gated Ca2+ channels; in contrast, when the cell is firing, the CF-PN signal is mediated by P/Q-type voltage-gated Ca2+ channels. When the CF input is paired with parallel fibre (PF) activity, the signal is locally amplified at the sites of PF-activated synapses according to the Vm at the time of the CF input, suggesting that the standing Vm is a critical parameter for the induction of PF synaptic plasticity. In this review, I analyse how the Vm can potentially play a role in cerebellar learning focussing, in particular, on the hyperpolarised state that appears to occur episodically, since PNs are mostly firing under physiological conditions. By revisiting the recent literature reporting in vivo recordings and synaptic plasticity studies, I speculate on how a putative role of the PN Vm can provide an interpretation for the results of these studies.
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Affiliation(s)
- Marco Canepari
- University of Grenoble Alpes, CNRS, LIPhy, F-38000, Grenoble, France. .,Laboratories of Excellence, Ion Channel Science and Therapeutics, Valbonne, France. .,Institut National de la Santé et Recherche Médicale, Paris, France.
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Herzfeld DJ, Hall NJ, Tringides M, Lisberger SG. Principles of operation of a cerebellar learning circuit. eLife 2020; 9:e55217. [PMID: 32352914 PMCID: PMC7255800 DOI: 10.7554/elife.55217] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 04/29/2020] [Indexed: 12/17/2022] Open
Abstract
We provide behavioral evidence using monkey smooth pursuit eye movements for four principles of cerebellar learning. Using a circuit-level model of the cerebellum, we link behavioral data to learning's neural implementation. The four principles are: (1) early, fast, acquisition driven by climbing fiber inputs to the cerebellar cortex, with poor retention; (2) learned responses of Purkinje cells guide transfer of learning from the cerebellar cortex to the deep cerebellar nucleus, with excellent retention; (3) functionally different neural signals are subject to learning in the cerebellar cortex versus the deep cerebellar nuclei; and (4) negative feedback from the cerebellum to the inferior olive reduces the magnitude of the teaching signal in climbing fibers and limits learning. Our circuit-level model, based on these four principles, explains behavioral data obtained by strategically manipulating the signals responsible for acquisition and recall of direction learning in smooth pursuit eye movements across multiple timescales.
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Affiliation(s)
- David J Herzfeld
- Department of Neurobiology, Duke University School of MedicineDurhamUnited States
| | - Nathan J Hall
- Department of Neurobiology, Duke University School of MedicineDurhamUnited States
| | - Marios Tringides
- Department of Neurobiology, Duke University School of MedicineDurhamUnited States
| | - Stephen G Lisberger
- Department of Neurobiology, Duke University School of MedicineDurhamUnited States
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The Origin of Physiological Local mGluR1 Supralinear Ca 2+ Signals in Cerebellar Purkinje Neurons. J Neurosci 2020; 40:1795-1809. [PMID: 31969470 DOI: 10.1523/jneurosci.2406-19.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 01/09/2020] [Accepted: 01/11/2020] [Indexed: 11/21/2022] Open
Abstract
In mouse cerebellar Purkinje neurons (PNs), the climbing fiber (CF) input provides a signal to parallel fiber (PF) synapses, triggering PF synaptic plasticity. This signal is given by supralinear Ca2+ transients, associated with the CF synaptic potential and colocalized with the PF Ca2+ influx, occurring only when PF activity precedes the CF input. Here, we unravel the biophysical determinants of supralinear Ca2+ signals associated with paired PF-CF synaptic activity. We used membrane potential (V m) and Ca2+ imaging to investigate the local CF-associated Ca2+ influx following a train of PF synaptic potentials in two cases: (1) when the dendritic V m is hyperpolarized below the resting V m, and (2) when the dendritic V m is at rest. We found that supralinear Ca2+ signals are mediated by type-1 metabotropic glutamate receptors (mGluR1s) when the CF input is delayed by 100-150 ms from the first PF input in both cases. When the dendrite is hyperpolarized only, however, mGluR1s boost neighboring T-type channels, providing a mechanism for local coincident detection of PF-CF activity. The resulting Ca2+ elevation is locally amplified by saturation of endogenous Ca2+ buffers produced by the PF-associated Ca2+ influx via the mGluR1-mediated nonselective cation conductance. In contrast, when the dendritic V m is at rest, mGluR1s increase dendritic excitability by inactivating A-type K+ channels, but this phenomenon is not restricted to the activated PF synapses. Thus, V m is likely a crucial parameter in determining PF synaptic plasticity, and the occurrence of hyperpolarization episodes is expected to play an important role in motor learning.SIGNIFICANCE STATEMENT In Purkinje neurons, parallel fiber synaptic plasticity, determined by coincident activation of the climbing fiber input, underlies cerebellar learning. We unravel the biophysical mechanisms allowing the CF input to produce a local Ca2+ signal exclusively at the sites of activated parallel fibers. We show that when the membrane potential is hyperpolarized with respect to the resting membrane potential, type-1 metabotropic glutamate receptors locally enhance Ca2+ influx mediated by T-type Ca2+ channels, and that this signal is amplified by saturation of endogenous buffer also mediated by the same receptors. The combination of these two mechanisms is therefore capable of producing a Ca2+ signal at the activated parallel fiber sites, suggesting a role of Purkinje neuron membrane potential in cerebellar learning.
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Najafi F, Medina JF. Bidirectional short-term plasticity during single-trial learning of cerebellar-driven eyelid movements in mice. Neurobiol Learn Mem 2019; 170:107097. [PMID: 31610225 DOI: 10.1016/j.nlm.2019.107097] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2019] [Revised: 09/13/2019] [Accepted: 10/09/2019] [Indexed: 11/27/2022]
Abstract
The brain is constantly monitoring its own performance, using error signals to trigger mechanisms of plasticity that help improve future behavior. Indeed, adaptive changes in behavior have been observed after a single error trial in many learning tasks, including cerebellum-dependent eyeblink conditioning. Here, we demonstrate that the plasticity underlying single-trial learning during eyeblink conditioning in mice is bidirectionally regulated by positive and negative prediction errors, has an ephemeral effect on behavior (decays in <1 min), and can be triggered in the absence of errors in performance. We suggest that these three properties of single-trial learning may be particularly useful for driving mechanisms of motor adaptation that can achieve optimal performance in the face of environmental disturbances with a fast timescale.
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Affiliation(s)
| | - Javier F Medina
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA.
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12
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Abstract
Supervised learning plays a key role in the operation of many biological and artificial neural networks. Analysis of the computations underlying supervised learning is facilitated by the relatively simple and uniform architecture of the cerebellum, a brain area that supports numerous motor, sensory, and cognitive functions. We highlight recent discoveries indicating that the cerebellum implements supervised learning using the following organizational principles: ( a) extensive preprocessing of input representations (i.e., feature engineering), ( b) massively recurrent circuit architecture, ( c) linear input-output computations, ( d) sophisticated instructive signals that can be regulated and are predictive, ( e) adaptive mechanisms of plasticity with multiple timescales, and ( f) task-specific hardware specializations. The principles emerging from studies of the cerebellum have striking parallels with those in other brain areas and in artificial neural networks, as well as some notable differences, which can inform future research on supervised learning and inspire next-generation machine-based algorithms.
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Affiliation(s)
- Jennifer L Raymond
- Department of Neurobiology, Stanford University School of Medicine, Stanford, California 94305, USA;
| | - Javier F Medina
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030, USA;
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13
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Two Distinct Sets of Ca 2+ and K + Channels Are Activated at Different Membrane Potentials by the Climbing Fiber Synaptic Potential in Purkinje Neuron Dendrites. J Neurosci 2019; 39:1969-1981. [PMID: 30630881 DOI: 10.1523/jneurosci.2155-18.2018] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Revised: 12/14/2018] [Accepted: 12/23/2018] [Indexed: 11/21/2022] Open
Abstract
In cerebellar Purkinje neuron dendrites, the transient depolarization associated with a climbing fiber (CF) EPSP activates voltage-gated Ca2+ channels (VGCCs), voltage-gated K+ channels (VGKCs), and Ca2+-activated SK and BK K+ channels. The resulting membrane potential (V m) and Ca2+ transients play a fundamental role in dendritic integration and synaptic plasticity of parallel fiber inputs. Here we report a detailed investigation of the kinetics of dendritic Ca2+ and K+ channels activated by CF-EPSPs, based on optical measurements of V m and Ca2+ transients and on a single-compartment NEURON model reproducing experimental data. We first measured V m and Ca2+ transients associated with CF-EPSPs at different initial V m, and we analyzed the changes in the Ca2+ transients produced by the block of each individual VGCCs, of A-type VGKCs and of SK and BK channels. Then, we constructed a model that includes six active ion channels to accurately match experimental signals and extract the physiological kinetics of each channel. We found that two different sets of channels are selectively activated. When the dendrite is hyperpolarized, CF-EPSPs mainly activate T-type VGCCs, SK channels, and A-type VGKCs that limit the transient V m ∼ <0 mV. In contrast, when the dendrite is depolarized, T-type VGCCs and A-type VGKCs are inactivated and CF-EPSPs activate P/Q-type VGCCs, high-voltage activated VGKCs, and BK channels, leading to Ca2+ spikes. Thus, the potentially activity-dependent regulation of A-type VGKCs, controlling the activation of this second set of channels, is likely to play a crucial role in signal integration and plasticity in Purkinje neuron dendrites.SIGNIFICANCE STATEMENT The climbing fiber synaptic input transiently depolarizes the dendrite of cerebellar Purkinje neurons generating a signal that plays a fundamental role in dendritic integration. This signal is mediated by two types of Ca2+ channels and four types of K+ channels. Thus, understanding the kinetics of all of these channels is crucial for understanding PN function. To obtain this information, we used an innovative strategy that merges ultrafast optical membrane potential and Ca2+ measurements, pharmacological analysis, and computational modeling. We found that, according to the initial membrane potential, the climbing fiber depolarizing transient activates two distinct sets of channels. Moreover, A-type K+ channels limit the activation of P/Q-type Ca2+ channels and associated K+ channels, thus preventing the generation of Ca2+ spikes.
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14
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Suvrathan A, Raymond JL. Depressed by Learning-Heterogeneity of the Plasticity Rules at Parallel Fiber Synapses onto Purkinje Cells. CEREBELLUM (LONDON, ENGLAND) 2018; 17:747-755. [PMID: 30069835 PMCID: PMC6550343 DOI: 10.1007/s12311-018-0968-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Climbing fiber-driven long-term depression (LTD) of parallel fiber synapses onto cerebellar Purkinje cells has long been investigated as a putative mechanism of motor learning. We recently discovered that the rules governing the induction of LTD at these synapses vary across different regions of the cerebellum. Here, we discuss the design of LTD induction protocols in light of this heterogeneity in plasticity rules. The analytical advantages of the cerebellum provide an opportunity to develop a deeper understanding of how the specific plasticity rules at synapses support the implementation of learning.
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Affiliation(s)
- Aparna Suvrathan
- Centre for Research in Neuroscience, Department of Neurology and Neurosurgery, Department of Pediatrics, Brain Repair and Integrative Neuroscience Program, the Research Institute of the McGill University Health Centre, McGill University, Montréal General Hospital, Montréal, Quebec, H3G 1A4, Canada
| | - Jennifer L Raymond
- Department of Neurobiology, Stanford University, Stanford, CA, 94305, USA.
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15
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Gaffield MA, Rowan MJM, Amat SB, Hirai H, Christie JM. Inhibition gates supralinear Ca 2+ signaling in Purkinje cell dendrites during practiced movements. eLife 2018; 7:36246. [PMID: 30117806 PMCID: PMC6120752 DOI: 10.7554/elife.36246] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 08/16/2018] [Indexed: 11/25/2022] Open
Abstract
Motor learning involves neural circuit modifications in the cerebellar cortex, likely through re-weighting of parallel fiber inputs onto Purkinje cells (PCs). Climbing fibers instruct these synaptic modifications when they excite PCs in conjunction with parallel fiber activity, a pairing that enhances climbing fiber-evoked Ca2+ signaling in PC dendrites. In vivo, climbing fibers spike continuously, including during movements when parallel fibers are simultaneously conveying sensorimotor information to PCs. Whether parallel fiber activity enhances climbing fiber Ca2+ signaling during motor behaviors is unknown. In mice, we found that inhibitory molecular layer interneurons (MLIs), activated by parallel fibers during practiced movements, suppressed parallel fiber enhancement of climbing fiber Ca2+ signaling in PCs. Similar results were obtained in acute slices for brief parallel fiber stimuli. Interestingly, more prolonged parallel fiber excitation revealed latent supralinear Ca2+ signaling. Therefore, the balance of parallel fiber and MLI input onto PCs regulates concomitant climbing fiber Ca2+ signaling.
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Affiliation(s)
| | - Matthew J M Rowan
- Max Planck Florida Institute for Neuroscience, Jupiter, United States
| | - Samantha B Amat
- Max Planck Florida Institute for Neuroscience, Jupiter, United States
| | - Hirokazu Hirai
- Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Jason M Christie
- Max Planck Florida Institute for Neuroscience, Jupiter, United States
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16
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Li B, Liu Y, Wan C, Liu Z, Wang M, Qi D, Yu J, Cai P, Xiao M, Zeng Y, Chen X. Mediating Short-Term Plasticity in an Artificial Memristive Synapse by the Orientation of Silica Mesopores. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1706395. [PMID: 29544021 DOI: 10.1002/adma.201706395] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Revised: 01/23/2018] [Indexed: 06/08/2023]
Abstract
Memristive synapses based on resistive switching are promising electronic devices that emulate the synaptic plasticity in neural systems. Short-term plasticity (STP), reflecting a temporal strengthening of the synaptic connection, allows artificial synapses to perform critical computational functions, such as fast response and information filtering. To mediate this fundamental property in memristive electronic devices, the regulation of the dynamic resistive change is necessary for an artificial synapse. Here, it is demonstrated that the orientation of mesopores in the dielectric silica layer can be used to modulate the STP of an artificial memristive synapse. The dielectric silica layer with vertical mesopores can facilitate the formation of a conductive pathway, which underlies a lower set voltage (≈1.0 V) compared to these with parallel mesopores (≈1.2 V) and dense amorphous silica (≈2.0 V). Also, the artificial memristive synapses with vertical mesopores exhibit the fastest current increase by successive voltage pulses. Finally, oriented silica mesopores are designed for varying the relaxation time of memory, and thus the successful mediation of STP is achieved. The implementation of mesoporous orientation provides a new perspective for engineering artificial synapses with multilevel learning and forgetting capability, which is essential for neuromorphic computing.
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Affiliation(s)
- Bin Li
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Yaqing Liu
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Changjin Wan
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Zhiyuan Liu
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Ming Wang
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Dianpeng Qi
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Jiancan Yu
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Pingqiang Cai
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Meng Xiao
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Yi Zeng
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
| | - Xiaodong Chen
- School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore
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17
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Cheron J, Cheron G. Beta-gamma burst stimulations of the inferior olive induce high-frequency oscillations in the deep cerebellar nuclei. Eur J Neurosci 2018; 48:2879-2889. [PMID: 29460990 DOI: 10.1111/ejn.13873] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2017] [Revised: 02/12/2018] [Accepted: 02/13/2018] [Indexed: 11/30/2022]
Abstract
The cerebellum displays various sorts of rhythmic activities covering both low- and high-frequency oscillations. These cerebellar high-frequency oscillations were observed in the cerebellar cortex. Here, we hypothesised that not only is the cerebellar cortex a generator of high-frequency oscillations but also that the deep cerebellar nuclei may also play a similar role. Thus, we analysed local field potentials and single-unit activities in the deep cerebellar nuclei before, during and after electric stimulation in the inferior olive of awake mice. A high-frequency oscillation of 350 Hz triggered by the stimulation of the inferior olive, within the beta-gamma range, was observed in the deep cerebellar nuclei. The amplitude and frequency of the oscillation were independent of the frequency of stimulation. This oscillation emerged during the period of stimulation and persisted after the end of the stimulation. The oscillation coincided with the inhibition of deep cerebellar neurons. As the inhibition of the deep cerebellar nuclei is related to inhibitory inputs from Purkinje cells, we speculate that the oscillation represents the unmasking of the synchronous activation of another subtype of deep cerebellar neuronal subtype, devoid of GABA receptors and under the direct control of the climbing fibres from the inferior olive. Still, the mechanism sustaining this oscillation remains to be deciphered. Our study sheds new light on the role of the olivo-cerebellar loop as the final output control of the intercerebellar circuitry.
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Affiliation(s)
- Julian Cheron
- Laboratory of Electrophysiology, Université de Mons, Mons, Belgium.,Laboratory of Neurophysiology and Movement Biomechanics, Neuroscience Institute, Université Libre de Bruxelles, Route de Lennik 808, Brussels, 1070, Belgium
| | - Guy Cheron
- Laboratory of Electrophysiology, Université de Mons, Mons, Belgium.,Laboratory of Neurophysiology and Movement Biomechanics, Neuroscience Institute, Université Libre de Bruxelles, Route de Lennik 808, Brussels, 1070, Belgium
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18
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Kano M, Watanabe T. Type-1 metabotropic glutamate receptor signaling in cerebellar Purkinje cells in health and disease. F1000Res 2017; 6:416. [PMID: 28435670 PMCID: PMC5381626 DOI: 10.12688/f1000research.10485.1] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 03/30/2017] [Indexed: 01/28/2023] Open
Abstract
The cerebellum is a brain structure involved in coordination, control, and learning of movements, as well as certain aspects of cognitive function. Purkinje cells are the sole output neurons from the cerebellar cortex and therefore play crucial roles in the overall function of the cerebellum. The type-1 metabotropic glutamate receptor (mGluR1) is a key “hub” molecule that is critically involved in the regulation of synaptic wiring, excitability, synaptic response, and synaptic plasticity of Purkinje cells. In this review, we aim to highlight how mGluR1 controls these events in Purkinje cells. We also describe emerging evidence that altered mGluR1 signaling in Purkinje cells underlies cerebellar dysfunctions in several clinically relevant mouse models of human ataxias.
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Affiliation(s)
- Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Takaki Watanabe
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
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19
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Chang CT, Zeng F, Li JX, Dong WS, Hu YD, Li GQ. Spatial summation of the short-term plasticity of a pair of organic heterogeneous junctions. RSC Adv 2017. [DOI: 10.1039/c6ra27406d] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Short-term plasticity of a pair of organic heterogeneous junctions could be linearly summed from those of the two sources.
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Affiliation(s)
- C. T. Chang
- Key Laboratory of Advanced Materials (MOE)
- School of Materials Science and Engineering
- Tsinghua University
- Beijing
- China
| | - F. Zeng
- Key Laboratory of Advanced Materials (MOE)
- School of Materials Science and Engineering
- Tsinghua University
- Beijing
- China
| | - J. X. Li
- Key Laboratory of Advanced Materials (MOE)
- School of Materials Science and Engineering
- Tsinghua University
- Beijing
- China
| | - W. S. Dong
- Key Laboratory of Advanced Materials (MOE)
- School of Materials Science and Engineering
- Tsinghua University
- Beijing
- China
| | - Y. D. Hu
- Key Laboratory of Advanced Materials (MOE)
- School of Materials Science and Engineering
- Tsinghua University
- Beijing
- China
| | - G. Q. Li
- Center for Brain Inspired Computing Research (CBICR)
- Tsinghua University
- Beijing 100084
- People's Republic of China
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20
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Suvrathan A, Payne HL, Raymond JL. Timing Rules for Synaptic Plasticity Matched to Behavioral Function. Neuron 2016; 92:959-967. [PMID: 27839999 DOI: 10.1016/j.neuron.2016.10.022] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Revised: 07/15/2016] [Accepted: 10/07/2016] [Indexed: 11/25/2022]
Abstract
It is widely assumed that the complexity of neural circuits enables them to implement diverse learning tasks using just a few generic forms of synaptic plasticity. In contrast, we report that synaptic plasticity can itself be precisely tuned to the requirements of a learning task. We found that the rules for induction of long-term and single-trial plasticity at parallel fiber-to-Purkinje cell synapses vary across cerebellar regions. In the flocculus, associative plasticity in vitro and in vivo is narrowly tuned for an interval of ∼120 ms, which compensates for the specific processing delay for error signals to reach the flocculus during oculomotor learning. In the vermis, which supports a range of behavioral functions, plasticity is induced by a range of intervals, with individual cells tuned for different intervals. Thus, plasticity at a single, anatomically defined type of synapse can have properties that vary in a way that is precisely matched to function.
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Affiliation(s)
- Aparna Suvrathan
- Department of Neurobiology, Stanford University, Stanford, CA 94305, USA.
| | - Hannah L Payne
- Department of Neurobiology, Stanford University, Stanford, CA 94305, USA
| | - Jennifer L Raymond
- Department of Neurobiology, Stanford University, Stanford, CA 94305, USA
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21
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Ly R, Bouvier G, Szapiro G, Prosser HM, Randall AD, Kano M, Sakimura K, Isope P, Barbour B, Feltz A. Contribution of postsynaptic T-type calcium channels to parallel fibre-Purkinje cell synaptic responses. J Physiol 2016; 594:915-36. [PMID: 26627919 DOI: 10.1113/jp271623] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 12/01/2015] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS At the parallel fibre-Purkinje cell glutamatergic synapse, little or no Ca(2+) entry takes place through postsynaptic neurotransmitter receptors, although postsynaptic calcium increases are clearly involved in the synaptic plasticity. Postsynaptic voltage-gated Ca(2+) channels therefore constitute the sole rapid postsynaptic Ca(2+) signalling mechanism, making it essential to understand how they contribute to the synaptic signalling. Using a selective T-type calcium channel antagonist, we describe a T-type component of the EPSC that is activated by the AMPA receptor-mediated depolarization of the spine and thus will contribute to the local calcium dynamics. This component can amount up to 20% of the EPSC, and this fraction is maintained even at the high frequencies sometimes encountered in sensory processing. Modelling based on our biophysical characterization of T-type calcium channels in Purkinje cells suggests that the brief spine EPSCs cause the activated T-type channels to deactivate rather than inactivate, enabling repetitive activation. ABSTRACT In the cerebellum, sensory information is conveyed to Purkinje cells (PC) via the granule cell/parallel fibre (PF) pathway. Plasticity at the PF-PC synapse is considered to be a mechanism of information storage in motor learning. The induction of synaptic plasticity in the cerebellum and elsewhere usually involves intracellular Ca(2+) signals. Unusually, postsynaptic Ca(2+) signalling in PF-PC spines does not involve ionotropic glutamatergic receptors because postsynaptic NMDA receptors are absent and the AMPA receptors are Ca(2+) -impermeable; postsynaptic voltage-gated Ca(2+) channels therefore constitute the sole rapid Ca(2+) signalling mechanism. Low-threshold activated T-type calcium channels are present at the synapse, although their contribution to PF-PC synaptic responses is unknown. Taking advantage of 3,5-dichloro-N-[1-(2,2-dimethyl-tetrahydro-pyran-4-ylmethyl)-4-fluoro-piperidin-4-ylmethyl]-benzamide, a selective T-type channel antagonist, we show in the mouse that inhibition of these channels reduces PF-PC excitatory postsynaptic currents and excitatory postsynaptic potentials by 15-20%. This contribution was preserved during sparse input and repetitive activity. We characterized the biophysical properties of native T-type channels in young animals and modelled their activation during simulated dendritic excitatory postsynaptic potential waveforms. The comparison of modelled and observed synaptic responses suggests that T-type channels only activate in spines that are strongly depolarized by their synaptic input, a process requiring a high spine neck resistance. This brief and local activation ensures that T-type channels rapidly deactivate, thereby limiting inactivation during repetitive synaptic activity. T-type channels are therefore ideally situated to provide synaptic Ca(2+) entry at PF-PC spines.
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Affiliation(s)
- Romain Ly
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), CNRS UMR 8197 and INSERM U1024, Paris, France
| | - Guy Bouvier
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), CNRS UMR 8197 and INSERM U1024, Paris, France
| | - German Szapiro
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), CNRS UMR 8197 and INSERM U1024, Paris, France
| | - Haydn M Prosser
- GlaxoSmithKline Pharmaceuticals, New Frontiers Science Park, Third Avenue, Harlow, UK., Wellcome Trust Sanger Institute, Hinxton, Cambridge, UK
| | - Andrew D Randall
- GlaxoSmithKline Pharmaceuticals, New Frontiers Science Park, Third Avenue, Harlow, UK.,School of Physiology and Pharmacology, Medical Sciences Building, University of Bristol, Bristol, UK
| | - Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, University of Tokyo, Tokyo, Japan
| | - Kenji Sakimura
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata, Japan
| | - Philippe Isope
- INCI, CNRS UPR 3212, Centre de Neurochimie, Strasbourg, France
| | - Boris Barbour
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), CNRS UMR 8197 and INSERM U1024, Paris, France
| | - Anne Feltz
- Ecole Normale Supérieure, Institut de Biologie de l'ENS (IBENS), CNRS UMR 8197 and INSERM U1024, Paris, France
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22
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Abstract
Marijuana affects neural functions through the binding of its active component (Δ9-THC) to cannabinoid receptors in the CNS. Recent studies have elucidated that endogenous ligands for cannabinoid receptors, endocannabinoids, serve as retrograde messengers at central synapses. Endocannabinoids are produced on demand in activity-dependent manners and released from postsynaptic neurons. The released endocannabinoids travel backward across the synapse, activate presynaptic CB1 cannabinoid receptors, and modulate presynaptic functions. Retrograde endocannabinoid signaling is crucial for certain forms of short-term and long-term synaptic plasticity at excitatory or inhibitory synapses in many brain regions, and thereby contributes to various aspects of brain function including learning and memory. Molecular identities of the CB1 receptor and enzymes involved in production and degradation of endocannabinoids have been elucidated. Anatomical studies have demonstrated unique distributions of these molecules around synapses, which provide morphological bases for the roles of endocannabinoids as retrograde messengers. CB1-knockout mice exhibit various behavioral abnormalities and multiple defects in synaptic plasticity, supporting the notion that endocannabinoid signaling is involved in various aspects of neural function. In this review article, the authors describe molecular mechanisms of the endocannabinoid-mediated synaptic modulation and its possible physiological significance. NEUROSCIENTIST 13(2):127—137, 2007.
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Affiliation(s)
- Yuki Hashimotodani
- Department of Neurophysiology, Graduate School of Medicine, Osaka University, Suita, Japan
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23
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Cannabinoid Type 2 Receptors Mediate a Cell Type-Specific Plasticity in the Hippocampus. Neuron 2016; 90:795-809. [PMID: 27133464 DOI: 10.1016/j.neuron.2016.03.034] [Citation(s) in RCA: 203] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Revised: 01/20/2016] [Accepted: 03/18/2016] [Indexed: 02/07/2023]
Abstract
Endocannabinoids (eCBs) exert major control over neuronal activity by activating cannabinoid receptors (CBRs). The functionality of the eCB system is primarily ascribed to the well-documented retrograde activation of presynaptic CB1Rs. We find that action potential-driven eCB release leads to a long-lasting membrane potential hyperpolarization in hippocampal principal cells that is independent of CB1Rs. The hyperpolarization, which is specific to CA3 and CA2 pyramidal cells (PCs), depends on the activation of neuronal CB2Rs, as shown by a combined pharmacogenetic and immunohistochemical approach. Upon activation, they modulate the activity of the sodium-bicarbonate co-transporter, leading to a hyperpolarization of the neuron. CB2R activation occurred in a purely self-regulatory manner, robustly altered the input/output function of CA3 PCs, and modulated gamma oscillations in vivo. To conclude, we describe a cell type-specific plasticity mechanism in the hippocampus that provides evidence for the neuronal expression of CB2Rs and emphasizes their importance in basic neuronal transmission.
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24
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Smeets CJLM, Verbeek DS. Climbing fibers in spinocerebellar ataxia: A mechanism for the loss of motor control. Neurobiol Dis 2016; 88:96-106. [PMID: 26792399 DOI: 10.1016/j.nbd.2016.01.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 11/19/2015] [Accepted: 01/09/2016] [Indexed: 11/26/2022] Open
Abstract
The spinocerebellar ataxias (SCAs) form an ever-growing group of neurodegenerative disorders causing dysfunction of the cerebellum and loss of motor control in patients. Currently, 41 different genetic causes have been identified, with each mutation affecting a different gene. Interestingly, these diverse genetic causes all disrupt cerebellar function and produce similar symptoms in patients. In order to understand the disease better, and define possible therapeutic targets for multiple SCAs, the field has been searching for common ground among the SCAs. In this review, we discuss the physiology of climbing fibers and the possibility that climbing fiber dysfunction is a point of convergence for at least a subset of SCAs.
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Affiliation(s)
- C J L M Smeets
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
| | - D S Verbeek
- Department of Genetics, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
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25
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Sachser RM, Crestani AP, Quillfeldt JA, Mello E Souza T, de Oliveira Alvares L. The cannabinoid system in the retrosplenial cortex modulates fear memory consolidation, reconsolidation, and extinction. Learn Mem 2015; 22:584-8. [PMID: 26572648 PMCID: PMC4749733 DOI: 10.1101/lm.039891.115] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Accepted: 09/29/2015] [Indexed: 12/04/2022]
Abstract
Despite the fact that the cannabinoid receptor type 1 (CB1R) plays a pivotal role in emotional memory processing in different regions of the brain, its function in the retrosplenial cortex (RSC) remains unknown. Here, using contextual fear conditioning in rats, we showed that a post-training intra-RSC infusion of the CB1R antagonist AM251 impaired, and the agonist CP55940 improved, long-term memory consolidation. Additionally, a post-reactivation infusion of AM251 enhanced memory reconsolidation, while CP55940 had the opposite effect. Finally, AM251 blocked extinction, whereas CP55940 facilitated it and maintained memory extinguished over time. Altogether, our data strongly suggest that the cannabinoid system of the RSC modulates emotional memory.
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MESH Headings
- Animals
- Cannabinoid Receptor Agonists/pharmacology
- Cannabinoid Receptor Antagonists/pharmacology
- Catheters, Indwelling
- Cerebral Cortex/drug effects
- Cerebral Cortex/metabolism
- Conditioning, Psychological/drug effects
- Conditioning, Psychological/physiology
- Cyclohexanols/pharmacology
- Extinction, Psychological/drug effects
- Extinction, Psychological/physiology
- Fear/drug effects
- Fear/physiology
- Male
- Memory Consolidation/drug effects
- Memory Consolidation/physiology
- Piperidines/pharmacology
- Pyrazoles/pharmacology
- Rats, Wistar
- Receptor, Cannabinoid, CB1/agonists
- Receptor, Cannabinoid, CB1/antagonists & inhibitors
- Receptor, Cannabinoid, CB1/metabolism
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Affiliation(s)
- Ricardo Marcelo Sachser
- Laboratório de Neurobiologia da Memória Departamento de Biofísica, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre 91501-970, Brazil Programa de Pós-Graduação em Neurociências, Universidade Federal do Rio Grande do Sul, Porto Alegre 90046-900, Brazil
| | - Ana Paula Crestani
- Laboratório de Psicobiologia e Neurocomputação, Departamento de Biofísica, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre 91501-970, Brazil Programa de Pós-Graduação em Neurociências, Universidade Federal do Rio Grande do Sul, Porto Alegre 90046-900, Brazil
| | - Jorge Alberto Quillfeldt
- Laboratório de Psicobiologia e Neurocomputação, Departamento de Biofísica, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre 91501-970, Brazil Programa de Pós-Graduação em Neurociências, Universidade Federal do Rio Grande do Sul, Porto Alegre 90046-900, Brazil
| | - Tadeu Mello E Souza
- Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre 90046-900, Brazil Programa de Pós-Graduação em Neurociências, Universidade Federal do Rio Grande do Sul, Porto Alegre 90046-900, Brazil
| | - Lucas de Oliveira Alvares
- Laboratório de Neurobiologia da Memória Departamento de Biofísica, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, Porto Alegre 91501-970, Brazil Programa de Pós-Graduação em Neurociências, Universidade Federal do Rio Grande do Sul, Porto Alegre 90046-900, Brazil
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26
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Zhang W, Schmelzeisen S, Parthier D, Frings S, Möhrlen F. Anoctamin Calcium-Activated Chloride Channels May Modulate Inhibitory Transmission in the Cerebellar Cortex. PLoS One 2015; 10:e0142160. [PMID: 26558388 PMCID: PMC4641602 DOI: 10.1371/journal.pone.0142160] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 10/19/2015] [Indexed: 01/18/2023] Open
Abstract
Calcium-activated chloride channels of the anoctamin (alias TMEM16) protein family fulfill critical functions in epithelial fluid transport, smooth muscle contraction and sensory signal processing. Little is known, however, about their contribution to information processing in the central nervous system. Here we examined the recent finding that a calcium-dependent chloride conductance impacts on GABAergic synaptic inhibition in Purkinje cells of the cerebellum. We asked whether anoctamin channels may underlie this chloride conductance. We identified two anoctamin channel proteins, ANO1 and ANO2, in the cerebellar cortex. ANO1 was expressed in inhibitory interneurons of the molecular layer and the granule cell layer. Both channels were expressed in Purkinje cells but, while ANO1 appeared to be retained in the cell body, ANO2 was targeted to the dendritic tree. Functional studies confirmed that ANO2 was involved in a calcium-dependent mode of ionic plasticity that reduces the efficacy of GABAergic synapses. ANO2 channels attenuated GABAergic transmission by increasing the postsynaptic chloride concentration, hence reducing the driving force for chloride influx. Our data suggest that ANO2 channels are involved in a Ca2+-dependent regulation of synaptic weight in GABAergic inhibition. Thus, in balance with the chloride extrusion mechanism via the co-transporter KCC2, ANO2 appears to regulate ionic plasticity in the cerebellum.
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Affiliation(s)
- Weiping Zhang
- Department of Animal Molecular Physiology, Centre of Organismal Studies, Im Neuenheimer Feld 504, Heidelberg University, Heidelberg, Germany
| | - Steffen Schmelzeisen
- Department of Animal Molecular Physiology, Centre of Organismal Studies, Im Neuenheimer Feld 504, Heidelberg University, Heidelberg, Germany
| | - Daniel Parthier
- Department of Animal Molecular Physiology, Centre of Organismal Studies, Im Neuenheimer Feld 504, Heidelberg University, Heidelberg, Germany
| | - Stephan Frings
- Department of Animal Molecular Physiology, Centre of Organismal Studies, Im Neuenheimer Feld 504, Heidelberg University, Heidelberg, Germany
| | - Frank Möhrlen
- Department of Animal Molecular Physiology, Centre of Organismal Studies, Im Neuenheimer Feld 504, Heidelberg University, Heidelberg, Germany
- * E-mail:
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27
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Suvarna Y, Maity N, Shivamurthy MC. Emerging Trends in Retrograde Signaling. Mol Neurobiol 2015; 53:2572-8. [PMID: 26081150 DOI: 10.1007/s12035-015-9280-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 06/02/2015] [Indexed: 01/09/2023]
Abstract
Retrograde signaling is defined as the signaling events leading from the plastids to the nucleus in plants and across the chemical synapse, from the postsynaptic neuron to the presynaptic neuron in animals. The discovery of various retrograde messengers has opened many avenues and clouds of thoughts as to the role of retrograde signaling. They have been implicated particularly in long-term potentiation (LTP) and synaptic plasticity. But the basic assumptions about retrograde signaling have not been studied upon for many years. This review focuses on established facts and hypothesis put forward in retrograde signaling.
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Affiliation(s)
- Yashasvi Suvarna
- Department of Pharmacology, M. S. Ramaiah Medical College, Bangalore, Karnataka, India.
| | - Nivedita Maity
- Department of Pharmacology, M. S. Ramaiah Medical College, Bangalore, Karnataka, India
| | - M C Shivamurthy
- Department of Pharmacology, M. S. Ramaiah Medical College, Bangalore, Karnataka, India
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Hernangómez M, Carrillo-Salinas FJ, Mecha M, Correa F, Mestre L, Loría F, Feliú A, Docagne F, Guaza C. Brain innate immunity in the regulation of neuroinflammation: therapeutic strategies by modulating CD200-CD200R interaction involve the cannabinoid system. Curr Pharm Des 2015; 20:4707-22. [PMID: 24588829 PMCID: PMC4157566 DOI: 10.2174/1381612820666140130202911] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Accepted: 01/29/2014] [Indexed: 11/24/2022]
Abstract
The central nervous system (CNS) innate immune response includes an arsenal of molecules and receptors expressed by professional phagocytes, glial cells and neurons that is involved in host defence and clearance of toxic and dangerous cell debris. However, any uncontrolled innate immune responses within the CNS are widely recognized as playing a major role in the development of autoimmune disorders and neurodegeneration, with multiple sclerosis (MS) Alzheimer's disease (AD) being primary examples. Hence, it is important to identify the key regulatory mechanisms involved in the control of CNS innate immunity and which could be harnessed to explore novel therapeutic avenues. Neuroimmune regulatory proteins (NIReg) such as CD95L, CD200, CD47, sialic acid, complement regulatory proteins (CD55, CD46, fH, C3a), HMGB1, may control the adverse immune responses in health and diseases. In the absence of these regulators, when neurons die by apoptosis, become infected or damaged, microglia and infiltrating immune cells are free to cause injury as well as an adverse inflammatory response in acute and chronic settings. We will herein provide new emphasis on the role of the pair CD200-CD200R in MS and its experimental models: experimental autoimmune encephalomyelitis (EAE) and Theiler’s virus induced demyelinating disease (TMEV-IDD). The interest of the cannabinoid system as inhibitor of inflammation prompt us to introduce our findings about the role of endocannabinoids (eCBs) in promoting CD200-CD200 receptor (CD200R) interaction and the benefits caused in TMEV-IDD. Finally, we also review the current data on CD200-CD200R interaction in AD, as well as, in the aging brain.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Carmen Guaza
- Neuroimmunology Group, Functional and Systems Neurobiology Department, Instituto Cajal, CSIC, 28002 Madrid, Spain.
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Jaafari N, Vogt KE, Saggau P, Leslie LM, Zecevic D, Canepari M. Combining Membrane Potential Imaging with Other Optical Techniques. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015; 859:103-25. [PMID: 26238050 DOI: 10.1007/978-3-319-17641-3_4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Membrane potential imaging using voltage-sensitive dyes can be combined with other optical techniques for a variety of applications. Combining voltage imaging with Ca2+ imaging allows correlating membrane potential changes with intracellular Ca2+ signals or with Ca2+ currents. Combining voltage imaging with uncaging techniques allows analyzing electrical signals elicited by photorelease of a particular molecule. This approach is also a useful tool to calibrate the change in fluorescence intensity in terms of membrane potential changes from different sites permitting spatial mapping of electrical activity. Finally, combining voltage imaging with optogenetics, in particular with channelrhodopsin stimulation, opens the gate to novel investigations of brain circuitries by allowing measurements of synaptic signals mediated by specific sets of neurons. Here we describe in detail the methods of membrane potential imaging in combination with other optical techniques and discus some important applications.
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Affiliation(s)
- Nadia Jaafari
- Inserm U836, Grenoble Institute of Neuroscience, Team 3, Grenoble Cedex 09, France
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Marcaggi P. Cerebellar Endocannabinoids: Retrograde Signaling from Purkinje Cells. THE CEREBELLUM 2014; 14:341-53. [DOI: 10.1007/s12311-014-0629-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Otsu Y, Marcaggi P, Feltz A, Isope P, Kollo M, Nusser Z, Mathieu B, Kano M, Tsujita M, Sakimura K, Dieudonné S. Activity-dependent gating of calcium spikes by A-type K+ channels controls climbing fiber signaling in Purkinje cell dendrites. Neuron 2014; 84:137-151. [PMID: 25220810 PMCID: PMC4183427 DOI: 10.1016/j.neuron.2014.08.035] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/17/2014] [Indexed: 12/01/2022]
Abstract
In cerebellar Purkinje cell dendrites, heterosynaptic calcium signaling induced by the proximal climbing fiber (CF) input controls plasticity at distal parallel fiber (PF) synapses. The substrate and regulation of this long-range dendritic calcium signaling are poorly understood. Using high-speed calcium imaging, we examine the role of active dendritic conductances. Under basal conditions, CF stimulation evokes T-type calcium signaling displaying sharp proximodistal decrement. Combined mGluR1 receptor activation and depolarization, two activity-dependent signals, unlock P/Q calcium spikes initiation and propagation, mediating efficient CF signaling at distal sites. These spikes are initiated in proximal smooth dendrites, independently from somatic sodium action potentials, and evoke high-frequency bursts of all-or-none fast-rising calcium transients in PF spines. Gradual calcium spike burst unlocking arises from increasing inactivation of mGluR1-modulated low-threshold A-type potassium channels located in distal dendrites. Evidence for graded activity-dependent CF calcium signaling at PF synapses refines current views on cerebellar supervised learning rules.
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Affiliation(s)
- Yo Otsu
- Inhibitory Transmission Team, IBENS, CNRS UMR UMR8197, INSERM U1024, Ecole Normale Supérieure, 75005 Paris, France
| | - Païkan Marcaggi
- Inhibitory Transmission Team, IBENS, CNRS UMR UMR8197, INSERM U1024, Ecole Normale Supérieure, 75005 Paris, France
| | - Anne Feltz
- Cerebellum Group, IBENS, CNRS UMR UMR8197, INSERM U1024, Ecole Normale Supérieure, 75005 Paris, France
| | - Philippe Isope
- Institut des Neurosciences Cellulaires et Intégratives, CNRS UPR 3212, 67000-Strasbourg, France
| | - Mihaly Kollo
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine of the Hungarian Academy of Sciences, 1083 Budapest, Hungary
| | - Zoltan Nusser
- Laboratory of Cellular Neurophysiology, Institute of Experimental Medicine of the Hungarian Academy of Sciences, 1083 Budapest, Hungary
| | - Benjamin Mathieu
- Imaging Facility, IBENS, CNRS UMR 8197, INSERM U1024, Ecole Normale Supérieure, 75005 Paris, France
| | - Masanobu Kano
- Department of Neurophysiology, Graduate School of Medicine, University of Tokyo, Tokyo 113-0033, Japan
| | - Mika Tsujita
- Center for Transdisciplinary Research, Niigata University, Niigata 950-2181, Japan
| | - Kenji Sakimura
- Department of Cellular Neurobiology, Brain Research Institute, Niigata University, Niigata 951-8585, Japan
| | - Stéphane Dieudonné
- Inhibitory Transmission Team, IBENS, CNRS UMR UMR8197, INSERM U1024, Ecole Normale Supérieure, 75005 Paris, France.
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Murataeva N, Straiker A, Mackie K. Parsing the players: 2-arachidonoylglycerol synthesis and degradation in the CNS. Br J Pharmacol 2014; 171:1379-91. [PMID: 24102242 PMCID: PMC3954479 DOI: 10.1111/bph.12411] [Citation(s) in RCA: 160] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 08/29/2013] [Accepted: 09/08/2013] [Indexed: 12/17/2022] Open
Abstract
UNLABELLED The endogenous cannabinoid signalling system, composed of endogenous cannabinoids, cannabinoid receptors and the enzymes that synthesize and degrade the endogenous cannabinoids, is much more complex than initially conceptualized. 2-Arachidonoylglycerol (2-AG) is the most abundant endocannabinoid and plays a major role in CNS development and synaptic plasticity. Over the past decade, many key players in 2-AG synthesis and degradation have been identified and characterized. Most 2-AG is synthesized from membrane phospholipids via sequential activation of a phospholipase Cβ and a diacylglycerol lipase, although other pathways may contribute in specialized settings. 2-AG breakdown is more complicated with at least eight different enzymes participating. These enzymes can either degrade 2-AG into its components, arachidonic acid and glycerol, or transform 2-AG into highly bioactive signal molecules. The implications of the precise temporal and spatial control of the expression and function of these pleiotropic metabolizing enzymes have only recently come to be appreciated. In this review, we will focus on the primary organization of the synthetic and degradative pathways of 2-AG and then discuss more recent findings and their implications, with an eye towards the biological and therapeutic implications of manipulating 2-AG synthesis and metabolism. LINKED ARTICLES This article is part of a themed section on Cannabinoids 2013. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-6.
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Affiliation(s)
- N Murataeva
- Department of Psychological and Brain Sciences, Gill Center for Biomolecular Science, Indiana UniversityBloomington, IN, USA
| | - A Straiker
- Department of Psychological and Brain Sciences, Gill Center for Biomolecular Science, Indiana UniversityBloomington, IN, USA
| | - K Mackie
- Department of Psychological and Brain Sciences, Gill Center for Biomolecular Science, Indiana UniversityBloomington, IN, USA
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KANO M. Control of synaptic function by endocannabinoid-mediated retrograde signaling. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2014; 90:235-250. [PMID: 25169670 PMCID: PMC4237895 DOI: 10.2183/pjab.90.235] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2014] [Accepted: 05/30/2014] [Indexed: 06/03/2023]
Abstract
Since the first reports in 2001, great advances have been made towards the understanding of endocannabinoid-mediated synaptic modulation. Electrophysiological studies have revealed that one of the two major endocannabinoids, 2-arachidonoylglycerol (2-AG), is produced from membrane lipids upon postsynaptic Ca(2+) elevation and/or activation of Gq/11-coupled receptors, and released from postsynaptic neurons. The released 2-AG then acts retrogradely onto presynaptic cannabinoid CB1 receptors and induces suppression of neurotransmitter release either transiently or persistently. These forms of 2-AG-mediated retrograde synaptic modulation are functional throughout the brain. The other major endocannabinoid, anandamide, mediates a certain form of endocannabinoid-mediated long-term depression (LTD). Anandamide also functions as an agonist for transient receptor potential vanilloid receptor type 1 (TRPV1) and mediates endocannabinoid-independent and TRPV1-dependent forms of LTD. It has also been demonstrated that the endocannabinoid system itself is plastic, which can be either up- or down-regulated by experimental or environmental conditions. In this review, I will make an overview of the mechanisms underlying endocannabinoid-mediated synaptic modulation.
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Affiliation(s)
- Masanobu KANO
- Department of Neurophysiology, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
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Yang Y, Lisberger SG. Interaction of plasticity and circuit organization during the acquisition of cerebellum-dependent motor learning. eLife 2013; 2:e01574. [PMID: 24381248 PMCID: PMC3871706 DOI: 10.7554/elife.01574] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Motor learning occurs through interactions between the cerebellar circuit and cellular plasticity at different sites. Previous work has established plasticity in brain slices and suggested plausible sites of behavioral learning. We now reveal what actually happens in the cerebellum during short-term learning. We monitor the expression of plasticity in the simple-spike firing of cerebellar Purkinje cells during trial-over-trial learning in smooth pursuit eye movements of monkeys. Our findings imply that: 1) a single complex-spike response driven by one instruction for learning causes short-term plasticity in a Purkinje cell’s mossy fiber/parallel-fiber input pathways; 2) complex-spike responses and simple-spike firing rate are correlated across the Purkinje cell population; and 3) simple-spike firing rate at the time of an instruction for learning modulates the probability of a complex-spike response, possibly through a disynaptic feedback pathway to the inferior olive. These mechanisms may participate in long-term motor learning. DOI:http://dx.doi.org/10.7554/eLife.01574.001 Practice makes perfect in many areas of life, such as playing sport or even just drinking coffee from a cup without spilling any. Our brains can learn and improve these motor skills through trial, error and learning, with such “motor learning” depending on the cerebellum, a part of the brain that helps to coordinate all kinds of movements. Motor learning is a product of the organization of the cerebellar circuit, which is well understood, and the “plasticity” in the synapses that determine how cerebellar neurons interact with each other. The cerebellum contains cells called Purkinje cells that receive distinctive inputs from two pathways: a pathway involving inputs from many parallel fibers, which convey signals related to sensory events or motor commands; and a pathway involving input from a single climbing-fiber, which conveys signals from a part of the brain called the inferior olive nucleus. Research on slices of brain has revealed many sites and forms of cerebellar plasticity that could participate in motor learning. In one form of plasticity, the strength of the synapses between the parallel fibers and the Purkinje cell can be changed when a signal sent along the climbing fiber arrives the Purkinje cell. Yang and Lisberger have now taken the next step by studying the cerebellum of a monkey as it performs a motor learning task. Remarkably these experiments show that the climbing fiber inputs cause plasticity of Purkinje cell activity, just as happens in the experiments on brain slices. Further, some learning in the cerebellum restricts further learning, so that the cerebellum puts boundaries on its own learning. Overall the results make clear how learning is a property of groups of neurons working together in a circuit, rather than simply of changes in the strength of specific synapses. By shedding light on what happens in the cerebellum during short-term motor learning, the work of Yang and Lisberger will benefit efforts to understand how the cerebellum is involved in motor learning on all time scales. DOI:http://dx.doi.org/10.7554/eLife.01574.002
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Affiliation(s)
- Yan Yang
- Department of Neurobiology, Duke University School of Medicine, Durham, United States
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Basu J, Srinivas KV, Cheung SK, Taniguchi H, Huang ZJ, Siegelbaum SA. A cortico-hippocampal learning rule shapes inhibitory microcircuit activity to enhance hippocampal information flow. Neuron 2013; 79:1208-21. [PMID: 24050406 PMCID: PMC3836574 DOI: 10.1016/j.neuron.2013.07.001] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/25/2013] [Indexed: 10/26/2022]
Abstract
How does coordinated activity between distinct brain regions implement a set of learning rules to sculpt information processing in a given neural circuit? Using interneuron cell-type-specific optical activation and pharmacogenetic silencing in vitro, we show that temporally precise pairing of direct entorhinal perforant path (PP) and hippocampal Schaffer collateral (SC) inputs to CA1 pyramidal cells selectively suppresses SC-associated perisomatic inhibition from cholecystokinin (CCK)-expressing interneurons. The CCK interneurons provide a surprisingly strong feedforward inhibitory drive to effectively control the coincident excitation of CA1 pyramidal neurons by convergent inputs. Thus, in-phase cortico-hippocampal activity provides a powerful heterosynaptic learning rule for long-term gating of information flow through the hippocampal excitatory macrocircuit by the silencing of the CCK inhibitory microcircuit.
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Affiliation(s)
- Jayeeta Basu
- Department of Neuroscience, Columbia University, 1051 Riverside Drive, New York, NY 10032, USA
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Quantification of the density of cooperative neighboring synapses required to evoke endocannabinoid signaling. Neuroscience 2013; 256:412-25. [PMID: 24183961 PMCID: PMC3928998 DOI: 10.1016/j.neuroscience.2013.10.041] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 10/07/2013] [Accepted: 10/22/2013] [Indexed: 11/23/2022]
Abstract
The spatial pattern of synapse activation may impact on synaptic plasticity. This applies to the synaptically-evoked endocannabinoid-mediated short-term depression at the parallel fiber (PF) to Purkinje cell synapse, the occurrence of which requires close proximity between the activated synapses. Here, we determine quantitatively this required proximity, helped by the geometrical organization of the cerebellar molecular layer. Transgenic mice expressing a calcium indicator selectively in granule cells enabled the imaging of action potential-evoked presynaptic calcium rise in isolated, single PFs. This measurement was used to derive the number of PFs activated within a beam of PFs stimulated in the molecular layer, from which the density of activated PFs (input density) was calculated. This density was on average 2.8 μm(-2) in sagittal slices and twice more in transverse slices. The synaptically-evoked endocannabinoid-mediated suppression of excitation (SSE) evoked by ten stimuli at 200 Hz was determined from the monitoring of either postsynaptic responses or presynaptic calcium rise. The SSE was significantly larger when recorded in transverse slices, where the input density is larger. The exponential description of the SSE plotted as a function of the input density suggests that the SSE is half reduced when the input density decreases from 6 to 2 μm(-2). We conclude that, although all PFs are truncated in an acute sagittal slice, half of them remain respondent to stimulation, and activated synapses need to be closer than 1.5 μm to synergize in endocannabinoid signaling.
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Muscarinic acetylcholine receptor activation blocks long-term potentiation at cerebellar parallel fiber-Purkinje cell synapses via cannabinoid signaling. Proc Natl Acad Sci U S A 2013; 110:11181-6. [PMID: 23776234 DOI: 10.1073/pnas.1221803110] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Muscarinic acetylcholine receptors (mAChRs) are known to modulate synaptic plasticity in various brain areas. A signaling pathway triggered by mAChR activation is the production and release of endocannabinoids that bind to type 1 cannabinoid receptors (CB1R) located on synaptic terminals. Using whole-cell patch-clamp recordings from rat cerebellar slices, we have demonstrated that the muscarinic agonist oxotremorine-m (oxo-m) blocks the induction of presynaptic long-term potentiation (LTP) at parallel fiber (PF)-Purkinje cell synapses in a CB1R-dependent manner. Under control conditions, LTP was induced by delivering 120 PF stimuli at 8 Hz. In contrast, no LTP was observed when oxo-m was present during tetanization. PF-LTP was restored when the CB1R antagonist N-1-(2,4-dichlorophenyl)-5-(4-iodophenyl)-4-methyl-N-1-piperidinyl-1H-pyrazole-3-carboxamide (AM251) was coapplied with oxo-m. Furthermore, the suppressive effect of oxo-m on PF-LTP was abrogated by the GDP analog GDP-β-S (applied intracellularly), the phospholipase C inhibitor U-73122, and the diacylglycerol lipase inhibitor tetrahydrolipstatin (THL), suggesting that cannabinoid synthesis results from the activation of Gq-coupled mAChRs present on Purkinje cells. The oxo-m-mediated suppression of LTP was also prevented in the presence of the M3 receptor antagonist DAU 5884, and was absent in M1/M3 receptor double-KO mice, identifying M3 receptors as primary oxo-m targets. Our findings allow for the possibility that cholinergic signaling in the cerebellum--which may result from long-term depression (LTD)-related disinhibition of cholinergic neurons in the vestibular nuclei--suppresses presynaptic LTP to prevent an up-regulation of transmitter release that opposes the reduction of postsynaptic responsiveness. This modulatory capacity of mAChR signaling could promote the functional penetrance of LTD.
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Hennig MH. Theoretical models of synaptic short term plasticity. Front Comput Neurosci 2013; 7:45. [PMID: 23626536 PMCID: PMC3630333 DOI: 10.3389/fncom.2013.00045] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 04/04/2013] [Indexed: 11/13/2022] Open
Abstract
Short term plasticity is a highly abundant form of rapid, activity-dependent modulation of synaptic efficacy. A shared set of mechanisms can cause both depression and enhancement of the postsynaptic response at different synapses, with important consequences for information processing. Mathematical models have been extensively used to study the mechanisms and roles of short term plasticity. This review provides an overview of existing models and their biological basis, and of their main properties. Special attention will be given to slow processes such as calcium channel inactivation and the effect of activation of presynaptic autoreceptors.
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Affiliation(s)
- Matthias H Hennig
- School of Informatics, Institute for Adaptive and Neural Computation, University of Edinburgh Edinburgh, UK
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39
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Abstract
Cerebellar long-term depression (LTD) is a form of long-term synaptic plasticity that is triggered by calcium(Ca2+) signals in the postsynaptic Purkinje cell. This Ca2+comes both from IP3-mediated release from intracellular Ca2+ stores, as well as from Ca2+ influx through voltage-gated Ca2+ channels. The Ca2+ signal that triggers LTD occurs locally within dendritic spines and is due to supralinear summation of signals coming from these two Ca2+ sources. The properties of this postsynaptic Ca2+signal can explain several features of LTD, such as its associativity, synapse specificity, and dependence on thetiming of synaptic activity, and can account for the slow kinetics of LTD expression. Thus, from a Ca2+ signaling perspective, LTD is one of the best understood forms of synaptic plasticity.
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Castillo PE, Younts TJ, Chávez AE, Hashimotodani Y. Endocannabinoid signaling and synaptic function. Neuron 2012; 76:70-81. [PMID: 23040807 DOI: 10.1016/j.neuron.2012.09.020] [Citation(s) in RCA: 721] [Impact Index Per Article: 60.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/14/2012] [Indexed: 12/17/2022]
Abstract
Endocannabinoids are key modulators of synaptic function. By activating cannabinoid receptors expressed in the central nervous system, these lipid messengers can regulate several neural functions and behaviors. As experimental tools advance, the repertoire of known endocannabinoid-mediated effects at the synapse, and their underlying mechanism, continues to expand. Retrograde signaling is the principal mode by which endocannabinoids mediate short- and long-term forms of plasticity at both excitatory and inhibitory synapses. However, growing evidence suggests that endocannabinoids can also signal in a nonretrograde manner. In addition to mediating synaptic plasticity, the endocannabinoid system is itself subject to plastic changes. Multiple points of interaction with other neuromodulatory and signaling systems have now been identified. In this Review, we focus on new advances in synaptic endocannabinoid signaling in the mammalian brain. The emerging picture not only reinforces endocannabinoids as potent regulators of synaptic function but also reveals that endocannabinoid signaling is mechanistically more complex and diverse than originally thought.
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Affiliation(s)
- Pablo E Castillo
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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Min R, Santello M, Nevian T. The computational power of astrocyte mediated synaptic plasticity. Front Comput Neurosci 2012; 6:93. [PMID: 23125832 PMCID: PMC3485583 DOI: 10.3389/fncom.2012.00093] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Accepted: 10/15/2012] [Indexed: 12/05/2022] Open
Abstract
Research in the last two decades has made clear that astrocytes play a crucial role in the brain beyond their functions in energy metabolism and homeostasis. Many studies have shown that astrocytes can dynamically modulate neuronal excitability and synaptic plasticity, and might participate in higher brain functions like learning and memory. With the plethora of astrocyte mediated signaling processes described in the literature today, the current challenge is to identify, which of these processes happen under what physiological condition, and how this shapes information processing and, ultimately, behavior. To answer these questions will require a combination of advanced physiological, genetical, and behavioral experiments. Additionally, mathematical modeling will prove crucial for testing predictions on the possible functions of astrocytes in neuronal networks, and to generate novel ideas as to how astrocytes can contribute to the complexity of the brain. Here, we aim to provide an outline of how astrocytes can interact with neurons. We do this by reviewing recent experimental literature on astrocyte-neuron interactions, discussing the dynamic effects of astrocytes on neuronal excitability and short- and long-term synaptic plasticity. Finally, we will outline the potential computational functions that astrocyte-neuron interactions can serve in the brain. We will discuss how astrocytes could govern metaplasticity in the brain, how they might organize the clustering of synaptic inputs, and how they could function as memory elements for neuronal activity. We conclude that astrocytes can enhance the computational power of neuronal networks in previously unexpected ways.
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Affiliation(s)
- Rogier Min
- Department of Physiology, University of Berne Berne, Switzerland
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Wang DJ, Yang D, Su LD, Xie YJ, Zhou L, Sun CL, Wang Y, Wang XX, Zhou L, Shen Y. Cytosolic phospholipase A2 alpha/arachidonic acid signaling mediates depolarization-induced suppression of excitation in the cerebellum. PLoS One 2012; 7:e41499. [PMID: 22927908 PMCID: PMC3425552 DOI: 10.1371/journal.pone.0041499] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2012] [Accepted: 06/21/2012] [Indexed: 12/22/2022] Open
Abstract
Background Depolarization-induced suppression of excitation (DSE) at parallel fiber-Purkinje cell synapse is an endocannabinoid-mediated short-term retrograde plasticity. Intracellular Ca2+ elevation is critical for the endocannabinoid production and DSE. Nevertheless, how elevated Ca2+ leads to DSE is unclear. Methodology/Principal Findings We utilized cytosolic phospholipase A2 alpha (cPLA2α) knock-out mice and whole-cell patch clamp in cerebellar slices to observed the action of cPLA2α/arachidonic acid signaling on DSE at parallel fiber-Purkinje cell synapse. Our data showed that DSE was significantly inhibited in cPLA2α knock-out mice, which was rescued by arachidonic acid. The degradation enzyme of 2-arachidonoylglycerol (2-AG), monoacylglycerol lipase (MAGL), blocked DSE, while another catabolism enzyme for N-arachidonoylethanolamine (AEA), fatty acid amide hydrolase (FAAH), did not affect DSE. These results suggested that 2-AG is responsible for DSE in Purkinje cells. Co-application of paxilline reversed the blockade of DSE by internal K+, indicating that large conductance Ca2+-activated potassium channel (BK) is sufficient to inhibit cPLA2α/arachidonic acid-mediated DSE. In addition, we showed that the release of 2-AG was independent of soluble NSF attachment protein receptor (SNARE), protein kinase C and protein kinase A. Conclusions/Significance Our data first showed that cPLA2α/arachidonic acid/2-AG signaling pathway mediates DSE at parallel fiber-Purkinje cell synapse.
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Affiliation(s)
- De-Juan Wang
- Key Laboratory of Medical Neurobiology of the Ministry of Health, Zhejiang Province Key Laboratory of Neurobiology, Department of Neurobiology, Zhejiang University School of Medicine, Hangzhou, People's Republic of China
| | - Dong Yang
- Key Laboratory of Medical Neurobiology of the Ministry of Health, Zhejiang Province Key Laboratory of Neurobiology, Department of Neurobiology, Zhejiang University School of Medicine, Hangzhou, People's Republic of China
| | - Li-Da Su
- Neuroscience Care Unit, The Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou, People's Republic of China
| | - Ya-jun Xie
- Key Laboratory of Medical Neurobiology of the Ministry of Health, Zhejiang Province Key Laboratory of Neurobiology, Department of Neurobiology, Zhejiang University School of Medicine, Hangzhou, People's Republic of China
| | - Lin Zhou
- Key Laboratory of Medical Neurobiology of the Ministry of Health, Zhejiang Province Key Laboratory of Neurobiology, Department of Neurobiology, Zhejiang University School of Medicine, Hangzhou, People's Republic of China
| | - Cheng-Long Sun
- Key Laboratory of Medical Neurobiology of the Ministry of Health, Zhejiang Province Key Laboratory of Neurobiology, Department of Neurobiology, Zhejiang University School of Medicine, Hangzhou, People's Republic of China
| | - Yin Wang
- Department of Neurobiology, Center of Scientific Technology, Cranial Cerebral Disease Lab, Ningxia Medical University, Yinchuan, People's Republic of China
| | - Xin-Xin Wang
- Key Laboratory of Medical Neurobiology of the Ministry of Health, Zhejiang Province Key Laboratory of Neurobiology, Department of Neurobiology, Zhejiang University School of Medicine, Hangzhou, People's Republic of China
| | - Liang Zhou
- Key Laboratory of Medical Neurobiology of the Ministry of Health, Zhejiang Province Key Laboratory of Neurobiology, Department of Neurobiology, Zhejiang University School of Medicine, Hangzhou, People's Republic of China
| | - Ying Shen
- Key Laboratory of Medical Neurobiology of the Ministry of Health, Zhejiang Province Key Laboratory of Neurobiology, Department of Neurobiology, Zhejiang University School of Medicine, Hangzhou, People's Republic of China
- * E-mail:
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43
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Chang W, Park JM, Kim J, Kim SJ. TRPC-Mediated Current Is Not Involved in Endocannabinoid-Induced Short-Term Depression in Cerebellum. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2012; 16:139-44. [PMID: 22563260 PMCID: PMC3339290 DOI: 10.4196/kjpp.2012.16.2.139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 03/25/2012] [Accepted: 03/25/2012] [Indexed: 02/04/2023]
Abstract
It has been reported that activation of metabotropic glutamate receptor 1 (mGluR1) can mediate endocannabinoid-induced short-term depression of synaptic transmission in cerebellar parallel fiber (PF)-Purkinje cell (PC) synapse. mGluR1 has signaling pathways involved in intracellular calcium increase which may contribute to endocannabinoid release. Two major mGluR1-evoked calcium signaling pathways are known: (1) slow-kinetic inward current carried by transient receptor potential canonical (TRPC) channel which is permeable to Ca(2+); (2) IP(3)-induced calcium release from intracellular calcium store. However, it is unclear how much each calcium source contributes to endocannabinoid signaling. Here, we investigated whether calcium influx through mGluR1-evoked TRPC channel contributes to endocannabinoid signaling in cerebellar Purkinje cells. At first, we applied SKF96365 to inhibit TRPC, which blocked endocannabinoid-induced short-term depression completely. However, an alternative TRP channel inhibitor, BTP2 did not affect endocannabinoid-induced short-term depression although it blocked mGluR1-evoked TRPC currents. Endocannabinoid signaling occurred normally even though the TRPC current was mostly blocked by BTP2. Our data imply that TRPC current does not play an important role in endocannabinoid signaling. We also suggest precaution in applying SKF96365 to inhibit TRP channels and propose BTP2 as an alternative TRPC inhibitor.
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Affiliation(s)
- Wonseok Chang
- Department of Physiology, Seoul National University College of Medicine, Seoul 110-799, Korea
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Mathur BN, Lovinger DM. Endocannabinoid-dopamine interactions in striatal synaptic plasticity. Front Pharmacol 2012; 3:66. [PMID: 22529814 PMCID: PMC3329863 DOI: 10.3389/fphar.2012.00066] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 04/02/2012] [Indexed: 11/13/2022] Open
Abstract
The nigrostriatal dopaminergic system is implicated in action control and learning. A large body of work has focused on the contribution of this system to modulation of the corticostriatal synapse, the predominant synapse type in the striatum. Signaling through the D2 dopamine receptor is necessary for endocannabinoid-mediated depression of corticostriatal glutamate release. Here we review the known details of this mechanism and discuss newly discovered signaling pathways interacting with this system that ultimately exert dynamic control of cortical input to the striatum and striatal output. This topic is timely with respect to Parkinson's disease given recent data indicating changes in the striatal endocannabinoid system in patients with this disorder.
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Affiliation(s)
- Brian N Mathur
- Section on Synaptic Pharmacology, Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, U.S. National Institutes of Health Rockville, MD, USA
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45
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Alger BE. Endocannabinoids at the synapse a decade after the dies mirabilis (29 March 2001): what we still do not know. J Physiol 2012; 590:2203-12. [PMID: 22289914 DOI: 10.1113/jphysiol.2011.220855] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Endogenous cannabinoids (endocannabinoids, eCBs) are ubiquitous regulators of synaptic transmission in the brain, mediating numerous forms of short- and long-term plasticity, and having strong influences on synapse formation and neurogenesis. Their roles as retrograde messengers that suppress both excitatory and inhibitory transmission are well-established. Yet, despite intensive investigation, many basic aspects of the eCB system are not understood. This brief review highlights recent advances, problems that remain unresolved, and avenues for future exploration. While 2-arachidonoylglycerol (2-AG) is probably the major eCB for intercellular CB1R-dependent signalling, anandamide (AEA) has come to the forefront in several novel contexts, both as a dual endovanilloid/endocannabinoid that regulates synaptic transmission acutely and as the source of a steady eCB tone in hippocampus. Complexities in the cellular processing of 2-AG are receiving renewed attention, as they are increasingly recognized as major determinants of how 2-AG affects cells. Long-standing fundamental issues such as the synthesis pathway for AEA and the molecular mechanism(s) underlying cellular uptake and release of eCBs remain problematical.
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Affiliation(s)
- Bradley E Alger
- Department of Physiology, University of Maryland School of Medicine, 655 W. Baltimore Street, Rm 5-025, Baltimore, MD 21201, USA.
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Sustained firing of cartwheel cells in the dorsal cochlear nucleus evokes endocannabinoid release and retrograde suppression of parallel fiber synapses. J Neurosci 2011; 31:15807-17. [PMID: 22049424 DOI: 10.1523/jneurosci.4088-11.2011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Neurons in many brain regions release endocannabinoids from their dendrites that act as retrograde signals to transiently suppress neurotransmitter release from presynaptic terminals. Little is known, however, about the physiological mechanisms of short-term endocannabinoid-mediated plasticity under physiological conditions. Here we investigate calcium-dependent endocannabinoid release from cartwheel cells (CWCs) of the mouse dorsal cochlear nucleus (DCN) in the auditory brainstem that provide feedforward inhibition onto DCN principal neurons. We report that sustained action potential firing by CWCs evokes endocannabinoid release in response to submicromolar elevation of dendritic calcium that transiently suppresses their parallel fiber (PF) inputs by >70%. Basal spontaneous CWC firing rates are insufficient to evoke tonic suppression of PF synapses. However, elevating CWC firing rates by stimulating PFs triggers the release of endocannabinoids and heterosynaptic suppression of PF inputs. Spike-evoked suppression by endocannabinoids selectively suppresses excitatory synapses, but glycinergic/GABAergic inputs onto CWCs are not affected. Our findings demonstrate a mechanism of transient plasticity mediated by endocannabinoids that heterosynaptically suppresses subsets of excitatory presynaptic inputs to CWCs that regulates feedforward inhibition of DCN principal neurons and may influence the output of the DCN.
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Post-Tetanic and Depolarization-Induced Suppression of Inhibition in Hippocampal Cell Cultures: Are Similar Mechanisms Involved? NEUROPHYSIOLOGY+ 2011. [DOI: 10.1007/s11062-011-9207-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2022]
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48
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Dendritic calcium signaling triggered by spontaneous and sensory-evoked climbing fiber input to cerebellar Purkinje cells in vivo. J Neurosci 2011; 31:10847-58. [PMID: 21795537 DOI: 10.1523/jneurosci.2525-10.2011] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Cerebellar Purkinje cells have one of the most elaborate dendritic trees in the mammalian CNS, receiving excitatory synaptic input from a single climbing fiber (CF) and from ∼200,000 parallel fibers. The dendritic Ca(2+) signals triggered by activation of these inputs are crucial for the induction of synaptic plasticity at both of these synaptic connections. We have investigated Ca(2+) signaling in Purkinje cell dendrites in vivo by combining targeted somatic or dendritic patch-clamp recording with simultaneous two-photon microscopy. Both spontaneous and sensory-evoked CF inputs triggered widespread Ca(2+) signals throughout the dendritic tree that were detectable even in individual spines of the most distal spiny branchlets receiving parallel fiber input. The amplitude of these Ca(2+) signals depended on dendritic location and could be modulated by membrane potential, reflecting modulation of dendritic spikes triggered by the CF input. Furthermore, the variability of CF-triggered Ca(2+) signals was regulated by GABAergic synaptic input. These results indicate that dendritic Ca(2+) signals triggered by sensory-evoked CF input can act as associative signals for synaptic plasticity in Purkinje cells in vivo and may differentially modulate plasticity at parallel fiber synapses depending on the location of synapses, firing state of the Purkinje cell, and ongoing GABAergic synaptic input.
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Abstract
Inhibitory neurons in the thalamic reticular nucleus (TRN) play a critical role in controlling information transfer between thalamus and neocortex. GABAergic synapses formed by TRN neurons contact both thalamic relay cells and neurons within TRN. These two types of synapses are thought to have distinct roles for the generation of thalamic network activity, but their selective regulation is poorly understood. In many areas throughout the brain, retrograde signaling mediated by endocannabinoids acts to dynamically regulate synaptic strength over both short and long time scales. However, retrograde signaling has never been demonstrated in the thalamus. Here, we show that depolarization-induced suppression of inhibition (DSI) is prominent at inhibitory synapses interconnecting TRN neurons. DSI is completely abolished in the presence of a cannabinoid receptor 1 (CB1R) antagonist and in mice lacking CB1Rs. DSI is prevented by DAG lipase inhibitors and prolonged by blocking the 2-arachidonoylglycerol (2-AG) degradation enzyme monoacylglycerol lipase, indicating that it is mediated by the release of 2-AG from TRN neurons. By contrast, DSI is not observed at TRN synapses targeting thalamic relay neurons. A combination of pharmacological and immunohistochemical data indicate that the differences in endocannabinoid signaling at the two synapses are mediated by a synapse-specific targeting of CB1Rs, as well as differences in endocannabinoid release between the two target neurons. Together, our results show that endocannabinoids control transmitter release at specific thalamic synapses, and could dynamically regulate sensory information processing and thalamus-mediated synchronous oscillations.
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Molecular and morphological configuration for 2-arachidonoylglycerol-mediated retrograde signaling at mossy cell-granule cell synapses in the dentate gyrus. J Neurosci 2011; 31:7700-14. [PMID: 21613483 DOI: 10.1523/jneurosci.5665-10.2011] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
2-Arachidonoylglycerol (2-AG) is the endocannabinoid that mediates retrograde suppression of neurotransmission in the brain. In the present study, we investigated the 2-AG signaling system at mossy cell (MC)-granule cell (GC) synapses in the mouse dentate gyrus, an excitatory recurrent circuit where endocannabinoids are thought to suppress epileptogenesis. First, we showed by electrophysiology that 2-AG produced by diacylglycerol lipase α (DGLα) mediated both depolarization-induced suppression of excitation and its enhancement by group I metabotropic glutamate receptor activation at MC-GC synapses, as they were abolished in DGLα-knock-out mice. Immunohistochemistry revealed that DGLα was enriched in the neck portion of GC spines forming synapses with MC terminals, whereas cannabinoid CB(1) receptors accumulated in the terminal portion of MC axons. On the other hand, the major 2-AG-degrading enzyme, monoacylglycerol lipase (MGL), was absent at MC-GC synapses but was expressed in astrocytes and some inhibitory terminals. Serial electron microscopy clarified that a given GC spine was innervated by a single MC terminal and also contacted nonsynaptically by other MC terminals making synapses with other GC spines in the neighborhood. MGL-expressing elements, however, poorly covered GC spines, amounting to 17% of the total surface of GC spines by astrocytes and 4% by inhibitory terminals. Our findings provide a basis for 2-AG-mediated retrograde suppression of MC-GC synaptic transmission and also suggest that 2-AG released from activated GC spines is readily accessible to nearby MC-GC synapses by escaping from enzymatic degradation. This molecular-anatomical configuration will contribute to adjust network activity in the dentate gyrus after enhanced excitation.
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