1
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Wu FC, Chen CY, Wang YW, You CB, Wang LY, Ruan J, Chou WY, Lai WC, Cheng HL. Modulating Neuromorphic Behavior of Organic Synaptic Electrolyte-Gated Transistors Through Microstructure Engineering and Potential Applications. ACS APPLIED MATERIALS & INTERFACES 2024; 16:41211-41222. [PMID: 39054697 PMCID: PMC11310909 DOI: 10.1021/acsami.4c05966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Revised: 06/03/2024] [Accepted: 07/17/2024] [Indexed: 07/27/2024]
Abstract
Organic synaptic transistors are a promising technology for advanced electronic devices with simultaneous computing and memory functions and for the application of artificial neural networks. In this study, the neuromorphic electrical characteristics of organic synaptic electrolyte-gated transistors are correlated with the microstructural and interfacial properties of the active layers. This is accomplished by utilizing a semiconducting/insulating polyblend-based pseudobilayer with embedded source and drain electrodes, referred to as PB-ESD architecture. Three variations of poly(3-hexylthiophene) (P3HT)/poly(methyl methacrylate) (PMMA) PB-ESD-based organic synaptic transistors are fabricated, each exhibiting distinct microstructures and electrical characteristics, thus serving excellent samples for exploring the critical factors influencing neuro-electrical properties. Poor microstructures of P3HT within the active layer and a flat active layer/ion-gel interface correspond to typical neuromorphic behaviors such as potentiated excitatory postsynaptic current (EPSC), paired-pulse facilitation (PPF), and short-term potentiation (STP). Conversely, superior microstructures of P3HT and a rough active layer/ion-gel interface correspond to significantly higher channel conductance and enhanced EPSC and PPF characteristics as well as long-term potentiation behavior. Such devices were further applied to the simulation of neural networks, which produced a good recognition accuracy. However, excessive PMMA penetration into the P3HT conducting channel leads to features of a depressed EPSC and paired-pulse depression, which are uncommon in organic synaptic transistors. The inclusion of a second gate electrode enables the as-prepared organic synaptic transistors to function as two-input synaptic logic gates, performing various logical operations and effectively mimicking neural modulation functions. Microstructure and interface engineering is an effective method to modulate the neuromorphic behavior of organic synaptic transistors and advance the development of bionic artificial neural networks.
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Affiliation(s)
- Fu-Chiao Wu
- Department
of Photonics, Meta-nanoPhotonics Center, National Cheng Kung University, Tainan 701, Taiwan
| | - Chun-Yu Chen
- Department
of Photonics, Meta-nanoPhotonics Center, National Cheng Kung University, Tainan 701, Taiwan
| | - Yu-Wu Wang
- Institute
of Photonics, National Changhua University
of Education, Changhua 500, Taiwan
| | - Chun-Bin You
- Department
of Photonics, Meta-nanoPhotonics Center, National Cheng Kung University, Tainan 701, Taiwan
| | - Li-Yun Wang
- Department
of Photonics, Meta-nanoPhotonics Center, National Cheng Kung University, Tainan 701, Taiwan
| | - Jrjeng Ruan
- Department
of Materials Science and Engineering, National
Cheng Kung University, Tainan 701, Taiwan
| | - Wei-Yang Chou
- Department
of Photonics, Meta-nanoPhotonics Center, National Cheng Kung University, Tainan 701, Taiwan
| | - Wei-Chih Lai
- Department
of Photonics, Meta-nanoPhotonics Center, National Cheng Kung University, Tainan 701, Taiwan
| | - Horng-Long Cheng
- Department
of Photonics, Meta-nanoPhotonics Center, National Cheng Kung University, Tainan 701, Taiwan
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2
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Beninger J, Rossbroich J, Tóth K, Naud R. Functional subtypes of synaptic dynamics in mouse and human. Cell Rep 2024; 43:113785. [PMID: 38363673 DOI: 10.1016/j.celrep.2024.113785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 12/08/2023] [Accepted: 01/27/2024] [Indexed: 02/18/2024] Open
Abstract
Synapses preferentially respond to particular temporal patterns of activity with a large degree of heterogeneity that is informally or tacitly separated into classes. Yet, the precise number and properties of such classes are unclear. Do they exist on a continuum and, if so, when is it appropriate to divide that continuum into functional regions? In a large dataset of glutamatergic cortical connections, we perform model-based characterization to infer the number and characteristics of functionally distinct subtypes of synaptic dynamics. In rodent data, we find five clusters that partially converge with transgenic-associated subtypes. Strikingly, the application of the same clustering method in human data infers a highly similar number of clusters, supportive of stable clustering. This nuanced dictionary of functional subtypes shapes the heterogeneity of cortical synaptic dynamics and provides a lens into the basic motifs of information transmission in the brain.
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Affiliation(s)
- John Beninger
- Center for Neural Dynamics and Artificial Intelligence, University of Ottawa, Ottawa, ON K1H 8M5, Canada; uOttawa Brain and Mind Research Institute, University of Ottawa, Ottawa, ON K1H 8M5, Canada; Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Julian Rossbroich
- Friedrich Miescher Institute for Biomedical Research, Basel, Switzerland; Faculty of Science, University of Basel, Basel, Switzerland
| | - Katalin Tóth
- Center for Neural Dynamics and Artificial Intelligence, University of Ottawa, Ottawa, ON K1H 8M5, Canada; uOttawa Brain and Mind Research Institute, University of Ottawa, Ottawa, ON K1H 8M5, Canada; Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada
| | - Richard Naud
- Center for Neural Dynamics and Artificial Intelligence, University of Ottawa, Ottawa, ON K1H 8M5, Canada; uOttawa Brain and Mind Research Institute, University of Ottawa, Ottawa, ON K1H 8M5, Canada; Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada; Department of Physics, University of Ottawa, Ottawa, ON K1H 8M5, Canada.
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3
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Bednarkiewicz A, Szalkowski M, Majak M, Korczak Z, Misiak M, Maćkowski S. All-Optical Data Processing with Photon-Avalanching Nanocrystalline Photonic Synapse. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023; 35:e2304390. [PMID: 37572370 DOI: 10.1002/adma.202304390] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 08/01/2023] [Indexed: 08/14/2023]
Abstract
Data processing and storage in electronic devices are typically performed as a sequence of elementary binary operations. Alternative approaches, such as neuromorphic or reservoir computing, are rapidly gaining interest where data processing is relatively slow, but can be performed in a more comprehensive way or massively in parallel, like in neuronal circuits. Here, time-domain all-optical information processing capabilities of photon-avalanching (PA) nanoparticles at room temperature are discovered. Demonstrated functionality resembles properties found in neuronal synapses, such as: paired-pulse facilitation and short-term internal memory, in situ plasticity, multiple inputs processing, and all-or-nothing threshold response. The PA-memory-like behavior shows capability of machine-learning-algorithm-free feature extraction and further recognition of 2D patterns with simple 2 input artificial neural network. Additionally, high nonlinearity of luminescence intensity in response to photoexcitation mimics and enhances spike-timing-dependent plasticity that is coherent in nature with the way a sound source is localized in animal neuronal circuits. Not only are yet unexplored fundamental properties of photon-avalanche luminescence kinetics studied, but this approach, combined with recent achievements in photonics, light confinement and guiding, promises all-optical data processing, control, adaptive responsivity, and storage on photonic chips.
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Affiliation(s)
- Artur Bednarkiewicz
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, ul. Okólna 2, Wroclaw, 50-422, Poland
| | - Marcin Szalkowski
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, ul. Okólna 2, Wroclaw, 50-422, Poland
- Nanophotonics Group, Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, 87-100, Toruń, ul. Grudziądzka 5, Poland
| | - Martyna Majak
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, ul. Okólna 2, Wroclaw, 50-422, Poland
| | - Zuzanna Korczak
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, ul. Okólna 2, Wroclaw, 50-422, Poland
| | - Małgorzata Misiak
- Institute of Low Temperature and Structure Research, Polish Academy of Sciences, ul. Okólna 2, Wroclaw, 50-422, Poland
| | - Sebastian Maćkowski
- Nanophotonics Group, Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Toruń, 87-100, Toruń, ul. Grudziądzka 5, Poland
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4
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Li C, Zhang X, Chen P, Zhou K, Yu J, Wu G, Xiang D, Jiang H, Wang M, Liu Q. Short-term synaptic plasticity in emerging devices for neuromorphic computing. iScience 2023; 26:106315. [PMID: 36950108 PMCID: PMC10025973 DOI: 10.1016/j.isci.2023.106315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023] Open
Abstract
Neuromorphic computing is a promising computing paradigm toward building next-generation artificial intelligence machines, in which diverse types of synaptic plasticity play an active role in information processing. Compared to long-term plasticity (LTP) forming the foundation of learning and memory, short-term plasticity (STP) is essential for critical computational functions. So far, the practical applications of LTP have been widely investigated, whereas the implementation of STP in hardware is still elusive. Here, we review the development of STP by bridging the physics in emerging devices and biological behaviors. We explore the computational functions of various STP in biology and review their recent progress. Finally, we discuss the main challenges of introducing STP into synaptic devices and offer the potential approaches to utilize STP to enrich systems' capabilities. This review is expected to provide prospective ideas for implementing STP in emerging devices and may promote the construction of high-level neuromorphic machines.
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Affiliation(s)
- Chao Li
- State Key Laboratory of Integrated Chip and System, Frontier Institute of Chip and System, Fudan University, Shanghai 200433, China
- Key Laboratory of Microelectronics Device & Integrated Technology, Institute of Microelectronics of Chinese Academy of Sciences, Beijing 100029, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xumeng Zhang
- State Key Laboratory of Integrated Chip and System, Frontier Institute of Chip and System, Fudan University, Shanghai 200433, China
- Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, Shanghai 200232, China
| | - Pei Chen
- State Key Laboratory of Integrated Chip and System, Frontier Institute of Chip and System, Fudan University, Shanghai 200433, China
| | - Keji Zhou
- State Key Laboratory of Integrated Chip and System, Frontier Institute of Chip and System, Fudan University, Shanghai 200433, China
- Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, Shanghai 200232, China
| | - Jie Yu
- State Key Laboratory of Integrated Chip and System, Frontier Institute of Chip and System, Fudan University, Shanghai 200433, China
- Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai 200433, China
| | - Guangjian Wu
- State Key Laboratory of Integrated Chip and System, Frontier Institute of Chip and System, Fudan University, Shanghai 200433, China
- Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, Shanghai 200232, China
| | - Du Xiang
- State Key Laboratory of Integrated Chip and System, Frontier Institute of Chip and System, Fudan University, Shanghai 200433, China
- Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, Shanghai 200232, China
| | - Hao Jiang
- State Key Laboratory of Integrated Chip and System, Frontier Institute of Chip and System, Fudan University, Shanghai 200433, China
- Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, Shanghai 200232, China
| | - Ming Wang
- State Key Laboratory of Integrated Chip and System, Frontier Institute of Chip and System, Fudan University, Shanghai 200433, China
- Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, Shanghai 200232, China
| | - Qi Liu
- State Key Laboratory of Integrated Chip and System, Frontier Institute of Chip and System, Fudan University, Shanghai 200433, China
- Zhangjiang Fudan International Innovation Center, Fudan University, Shanghai 200433, China
- Shanghai Qi Zhi Institute, Shanghai 200232, China
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5
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MacLeod KM, Pandya S. Expression and Neurotransmitter Association of the Synaptic Calcium Sensor Synaptotagmin in the Avian Auditory Brain Stem. J Assoc Res Otolaryngol 2022; 23:701-720. [PMID: 35999323 PMCID: PMC9789253 DOI: 10.1007/s10162-022-00863-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Accepted: 07/12/2022] [Indexed: 01/31/2023] Open
Abstract
In the avian auditory brain stem, acoustic timing and intensity cues are processed in separate, parallel pathways via the two divisions of the cochlear nucleus, nucleus angularis (NA) and nucleus magnocellularis (NM). Differences in excitatory and inhibitory synaptic properties, such as release probability and short-term plasticity, contribute to differential processing of the auditory nerve inputs. We investigated the distribution of synaptotagmin, a putative calcium sensor for exocytosis, via immunohistochemistry and double immunofluorescence in the embryonic and hatchling chick brain stem (Gallus gallus). We found that the two major isoforms, synaptotagmin 1 (Syt1) and synaptotagmin 2 (Syt2), showed differential expression. In the NM, anti-Syt2 label was strong and resembled the endbulb terminals of the auditory nerve inputs, while anti-Syt1 label was weaker and more punctate. In NA, both isoforms were intensely expressed throughout the neuropil. A third isoform, synaptotagmin 7 (Syt7), was largely absent from the cochlear nuclei. In nucleus laminaris (NL, the target nucleus of NM), anti-Syt2 and anti-Syt7 strongly labeled the dendritic lamina. These patterns were established by embryonic day 18 and persisted to postnatal day 7. Double-labeling immunofluorescence showed that Syt1 and Syt2 were associated with vesicular glutamate transporter 2 (VGluT2), but not vesicular GABA transporter (VGAT), suggesting that these Syt isoforms were localized to excitatory, but not inhibitory, terminals. These results suggest that Syt2 is the major calcium binding protein underlying excitatory neurotransmission in the timing pathway comprising NM and NL, while Syt2 and Syt1 regulate excitatory transmission in the parallel intensity pathway via cochlear nucleus NA.
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Affiliation(s)
- Katrina M MacLeod
- Department of Biology, University of Maryland, College Park, MD, 20742, USA.
| | - Sangeeta Pandya
- Department of Biology, University of Maryland, College Park, MD, 20742, USA
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6
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Wang J, Xu J, Wu J, Xu Q. Geometric characterization of dynamical structure for neural firing activities induced by inhibitory pulse. Cogn Neurodyn 2022; 16:1505-1524. [PMID: 36408077 PMCID: PMC9666638 DOI: 10.1007/s11571-022-09799-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 02/28/2022] [Accepted: 03/08/2022] [Indexed: 11/25/2022] Open
Abstract
In general, inhibitory stimuli are thought to inhibit neuronal firing, but they may actually enhance firing sometimes, such as post-inhibitory rebound spike (PIR spike) and post-inhibitory facilitation (PIF) phenomena, which play an important role in human neuronal activities. We study responses to inhibitory pulse in a classical neuron model (Quartic adaptive Integrate-and-fire model) well known to reproduce a number of biologically realistic behaviors. The three phenomena that we study are PIR, in which a neuron fires after an inhibitory pulse, and PIF, in which a subthreshold excitatory input can induce a spike if it is applied with proper timing after an inhibitory pulse, as well as period firing after inhibitory pulse. When the system features focus and saddle two equilibriums, the three phenomena will be occurred under the inhibitory pulse, while all three phenomena will not be induced when the system features node and saddle two equilibriums. Using dynamical systems theory, we explain the threshold mechanism of enhancement of neural firing response induced by inhibitory pulse and analyze the origin of these phenomena from several factors. We also describe the geometric characterization of dynamical structures of these three phenomena. This study therefore enrich the paradoxical phenomena that induced by inhibitory input and advance our understanding of its role.
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Affiliation(s)
- Junjie Wang
- School of Mathematics and Information Science, Guangxi University, Nanning, 530004 China
| | - Jieqiong Xu
- School of Mathematics and Information Science, Guangxi University, Nanning, 530004 China
- Scientific Research Center of Engineering Mechanics, Guangxi University, Nanning, 530004 China
| | - Jianmei Wu
- School of Mathematics and Information Science, Guangxi University, Nanning, 530004 China
| | - Qixiang Xu
- School of Mathematics and Information Science, Guangxi University, Nanning, 530004 China
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7
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Pietras B, Schmutz V, Schwalger T. Mesoscopic description of hippocampal replay and metastability in spiking neural networks with short-term plasticity. PLoS Comput Biol 2022; 18:e1010809. [PMID: 36548392 PMCID: PMC9822116 DOI: 10.1371/journal.pcbi.1010809] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 01/06/2023] [Accepted: 12/11/2022] [Indexed: 12/24/2022] Open
Abstract
Bottom-up models of functionally relevant patterns of neural activity provide an explicit link between neuronal dynamics and computation. A prime example of functional activity patterns are propagating bursts of place-cell activities called hippocampal replay, which is critical for memory consolidation. The sudden and repeated occurrences of these burst states during ongoing neural activity suggest metastable neural circuit dynamics. As metastability has been attributed to noise and/or slow fatigue mechanisms, we propose a concise mesoscopic model which accounts for both. Crucially, our model is bottom-up: it is analytically derived from the dynamics of finite-size networks of Linear-Nonlinear Poisson neurons with short-term synaptic depression. As such, noise is explicitly linked to stochastic spiking and network size, and fatigue is explicitly linked to synaptic dynamics. To derive the mesoscopic model, we first consider a homogeneous spiking neural network and follow the temporal coarse-graining approach of Gillespie to obtain a "chemical Langevin equation", which can be naturally interpreted as a stochastic neural mass model. The Langevin equation is computationally inexpensive to simulate and enables a thorough study of metastable dynamics in classical setups (population spikes and Up-Down-states dynamics) by means of phase-plane analysis. An extension of the Langevin equation for small network sizes is also presented. The stochastic neural mass model constitutes the basic component of our mesoscopic model for replay. We show that the mesoscopic model faithfully captures the statistical structure of individual replayed trajectories in microscopic simulations and in previously reported experimental data. Moreover, compared to the deterministic Romani-Tsodyks model of place-cell dynamics, it exhibits a higher level of variability regarding order, direction and timing of replayed trajectories, which seems biologically more plausible and could be functionally desirable. This variability is the product of a new dynamical regime where metastability emerges from a complex interplay between finite-size fluctuations and local fatigue.
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Affiliation(s)
- Bastian Pietras
- Institute for Mathematics, Technische Universität Berlin, Berlin, Germany
- Bernstein Center for Computational Neuroscience, Berlin, Germany
- Department of Information and Communication Technologies, Universitat Pompeu Fabra, Barcelona, Spain
| | - Valentin Schmutz
- Brain Mind Institute, School of Computer and Communication Sciences and School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland
| | - Tilo Schwalger
- Institute for Mathematics, Technische Universität Berlin, Berlin, Germany
- Bernstein Center for Computational Neuroscience, Berlin, Germany
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8
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Gao F, Ma J, Yu YQ, Gao XF, Bai Y, Sun Y, Liu J, Liu X, Barry DM, Wilhelm S, Piccinni-Ash T, Wang N, Liu D, Ross RA, Hao Y, Huang X, Jia JJ, Yang Q, Zheng H, van Nispen J, Chen J, Li H, Zhang J, Li YQ, Chen ZF. A non-canonical retina-ipRGCs-SCN-PVT visual pathway for mediating contagious itch behavior. Cell Rep 2022; 41:111444. [PMID: 36198265 PMCID: PMC9595067 DOI: 10.1016/j.celrep.2022.111444] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 08/10/2022] [Accepted: 09/12/2022] [Indexed: 11/23/2022] Open
Abstract
Contagious itch behavior informs conspecifics of adverse environment and is crucial for the survival of social animals. Gastrin-releasing peptide (GRP) and its receptor (GRPR) in the suprachiasmatic nucleus (SCN) of the hypothalamus mediates contagious itch behavior in mice. Here, we show that intrinsically photosensitive retina ganglion cells (ipRGCs) convey visual itch information, independently of melanopsin, from the retina to GRP neurons via PACAP-PAC1R signaling. Moreover, GRPR neurons relay itch information to the paraventricular nucleus of the thalamus (PVT). Surprisingly, neither the visual cortex nor superior colliculus is involved in contagious itch. In vivo calcium imaging and extracellular recordings reveal contagious itch-specific neural dynamics of GRPR neurons. Thus, we propose that the retina-ipRGC-SCN-PVT pathway constitutes a previously unknown visual pathway that probably evolved for motion vision that encodes salient environmental cues and enables animals to imitate behaviors of conspecifics as an anticipatory mechanism to cope with adverse conditions. It has been shown that GRP-GRPR neuropeptide signaling in the SCN is important for contagious itch behavior in mice. Gao et al. find that SCN-projecting ipRGCs are sufficient to relay itch information from the retina to the SCN by releasing neuropeptide PACAP to activate the GRP-GRPR pathway.
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Affiliation(s)
- Fang Gao
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA,Departments of Anesthesiology, Medicine, Psychiatry and Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jun Ma
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA,Departments of Anesthesiology, Medicine, Psychiatry and Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Yao-Qing Yu
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA,Departments of Anesthesiology, Medicine, Psychiatry and Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA,Institute for Biomedical Sciences of Pain, Tangdu Hospital, Fourth Military Medical University, Xi’an 710038, P. R. China
| | - Xiao-Fei Gao
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA,Departments of Anesthesiology, Medicine, Psychiatry and Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA,Present address: Translational Research Institute of Brain and Brain-like Intelligence, Shanghai Fourth People’s Hospital, School of Medicine, Tongji University, Shanghai 200434, P. R. China
| | - Yang Bai
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA,Department of Anatomy, Histology and Embryology & K.K. Leung Brain Research Centre, Fourth Military Medical University, Xi’an 710032, P. R. China,Present address: Department of Neurosurgery, General Hospital of Northern Theater Command, Shenyang 110016, P. R. China
| | - Yi Sun
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA,Department of Anatomy, Histology and Embryology & K.K. Leung Brain Research Centre, Fourth Military Medical University, Xi’an 710032, P. R. China,Present address: Binzhou Medical University, Yantai 264003, P. R. China
| | - Juan Liu
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA,Departments of Anesthesiology, Medicine, Psychiatry and Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Xianyu Liu
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA,Departments of Anesthesiology, Medicine, Psychiatry and Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Devin M. Barry
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA,Departments of Anesthesiology, Medicine, Psychiatry and Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Steven Wilhelm
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA,Departments of Anesthesiology, Medicine, Psychiatry and Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Tyler Piccinni-Ash
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA,Departments of Anesthesiology, Medicine, Psychiatry and Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Na Wang
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA,Departments of Anesthesiology, Medicine, Psychiatry and Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA,Present address: Shandong Provincial Hospital for Skin Diseases & Shandong Provincial Institute of Dermatology and Venereology, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, P. R. China
| | - Dongyang Liu
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA,Departments of Anesthesiology, Medicine, Psychiatry and Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA,Department of Pain Management, the State Key Clinical Specialty in Pain Medicine, the Second Affiliated Hospital, Guangzhou Medical University, Guangzhou 510260, P.R. China
| | - Rachel A. Ross
- Department of Neuroscience, Psychiatry and Medicine, Albert Einstein College of Medicine Rose F. Kennedy Center, Bronx, NY, USA
| | - Yan Hao
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA,Departments of Anesthesiology, Medicine, Psychiatry and Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA,Present address: Department of Pediatrics, Tongji Hospital, Tongji Medical College, HuaZhong University of Science and Technology, Wuhan 430030, P. R. China
| | - Xu Huang
- Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science and Institute for Medical and Engineering Innovation, Eye & ENT Hospital, Fudan University, Shanghai 200031, P.R. China
| | - Jin-Jing Jia
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA,Departments of Anesthesiology, Medicine, Psychiatry and Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA,Present address: College of Life Sciences, Xinyang Normal University, Xinyang 464000, P. R. China
| | - Qianyi Yang
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA,Departments of Anesthesiology, Medicine, Psychiatry and Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Hao Zheng
- Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science and Institute for Medical and Engineering Innovation, Eye & ENT Hospital, Fudan University, Shanghai 200031, P.R. China
| | - Johan van Nispen
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA,Departments of Anesthesiology, Medicine, Psychiatry and Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA,Present address: Saint Louis University School of Medicine, St. Louis, MO 63104, USA
| | - Jun Chen
- Institute for Biomedical Sciences of Pain, Tangdu Hospital, Fourth Military Medical University, Xi’an 710038, P. R. China
| | - Hui Li
- Department of Anatomy, Histology and Embryology & K.K. Leung Brain Research Centre, Fourth Military Medical University, Xi’an 710032, P. R. China
| | - Jiayi Zhang
- Institutes of Brain Science, State Key Laboratory of Medical Neurobiology, MOE Frontiers Center for Brain Science and Institute for Medical and Engineering Innovation, Eye & ENT Hospital, Fudan University, Shanghai 200031, P.R. China
| | - Yun-Qing Li
- Department of Anatomy, Histology and Embryology & K.K. Leung Brain Research Centre, Fourth Military Medical University, Xi’an 710032, P. R. China
| | - Zhou-Feng Chen
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, St. Louis, MO 63110, USA,Departments of Anesthesiology, Medicine, Psychiatry and Developmental Biology, Washington University School of Medicine, St. Louis, MO 63110, USA,Lead contact,Correspondence:
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9
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Mondal Y, Pena RFO, Rotstein HG. Temporal filters in response to presynaptic spike trains: interplay of cellular, synaptic and short-term plasticity time scales. J Comput Neurosci 2022; 50:395-429. [DOI: 10.1007/s10827-022-00822-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 05/06/2022] [Accepted: 05/25/2022] [Indexed: 10/16/2022]
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10
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Deng PY, Kumar A, Cavalli V, Klyachko VA. FMRP regulates GABA A receptor channel activity to control signal integration in hippocampal granule cells. Cell Rep 2022; 39:110820. [PMID: 35584668 DOI: 10.1016/j.celrep.2022.110820] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 03/11/2022] [Accepted: 04/21/2022] [Indexed: 11/29/2022] Open
Abstract
Fragile X syndrome, the most common inherited form of intellectual disability, is caused by loss of fragile X mental retardation protein (FMRP). GABAergic system dysfunction is one of the hallmarks of FXS, yet the underlying mechanisms remain poorly understood. Here, we report that FMRP interacts with GABAA receptor (GABAAR) and modulates its single-channel activity. Specifically, FMRP regulates spontaneous GABAAR opening through modulating its single-channel conductance and open probability in dentate granule cells. FMRP loss reduces spontaneous GABAAR activity underlying tonic inhibition, while N-terminal FMRP fragment (aa 1-297) is sufficient to rapidly normalize tonic inhibition in Fmr1 knockout (KO) granule cells. FMRP-GABAAR interaction is supported by co-immunoprecipitation of FMRP with at least one GABAAR subunit, the α5. Functionally, FMRP-GABAAR interaction ensures accuracy of coincidence detection of granule cells, which is markedly reduced in Fmr1 KOs. Our study reveals a mechanism underlying FMRP regulation of the GABAergic system and information processing in the hippocampus.
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Affiliation(s)
- Pan-Yue Deng
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Ajeet Kumar
- Department of Neuroscience, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Valeria Cavalli
- Department of Neuroscience, Washington University School of Medicine, St Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, St Louis, MO 63110, USA; Center of Regenerative Medicine, Washington University School of Medicine, St Louis, MO 63110, USA
| | - Vitaly A Klyachko
- Department of Cell Biology and Physiology, Washington University School of Medicine, St Louis, MO 63110, USA; Hope Center for Neurological Disorders, Washington University School of Medicine, St Louis, MO 63110, USA.
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11
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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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12
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Auditory Brainstem Models: Adapting Cochlear Nuclei Improve Spatial Encoding by the Medial Superior Olive in Reverberation. J Assoc Res Otolaryngol 2021; 22:289-318. [PMID: 33861395 DOI: 10.1007/s10162-021-00797-0] [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: 03/26/2020] [Accepted: 03/22/2021] [Indexed: 10/21/2022] Open
Abstract
Listeners typically perceive a sound as originating from the direction of its source, even as direct sound is followed milliseconds later by reflected sound from multiple different directions. Early-arriving sound is emphasised in the ascending auditory pathway, including the medial superior olive (MSO) where binaural neurons encode the interaural-time-difference (ITD) cue for spatial location. Perceptually, weighting of ITD conveyed during rising sound energy is stronger at 600 Hz than at 200 Hz, consistent with the minimum stimulus rate for binaural adaptation, and with the longer reverberation times at 600 Hz, compared with 200 Hz, in many natural outdoor environments. Here, we computationally explore the combined efficacy of adaptation prior to the binaural encoding of ITD cues, and excitatory binaural coincidence detection within MSO neurons, in emphasising ITDs conveyed in early-arriving sound. With excitatory inputs from adapting, nonlinear model spherical bushy cells (SBCs) of the bilateral cochlear nuclei, a nonlinear model MSO neuron with low-threshold potassium channels reproduces the rate-dependent emphasis of rising vs. peak sound energy in ITD encoding; adaptation is equally effective in the model MSO. Maintaining adaptation in model SBCs, and adjusting membrane speed in model MSO neurons, 'left' and 'right' populations of computationally efficient, linear model SBCs and MSO neurons reproduce this stronger weighting of ITD conveyed during rising sound energy at 600 Hz compared to 200 Hz. This hemispheric population model demonstrates a link between strong weighting of spatial information during rising sound energy, and correct unambiguous lateralisation of a speech source in reverberation.
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13
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Presynaptic endoplasmic reticulum regulates short-term plasticity in hippocampal synapses. Commun Biol 2021; 4:241. [PMID: 33623091 PMCID: PMC7902852 DOI: 10.1038/s42003-021-01761-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 01/25/2021] [Indexed: 01/31/2023] Open
Abstract
Short-term plasticity preserves a brief history of synaptic activity that is communicated to the postsynaptic neuron. This is primarily regulated by a calcium signal initiated by voltage dependent calcium channels in the presynaptic terminal. Imaging studies of CA3-CA1 synapses reveal the presence of another source of calcium, the endoplasmic reticulum (ER) in all presynaptic terminals. However, the precise role of the ER in modifying STP remains unexplored. We performed in-silico experiments in synaptic geometries based on reconstructions of the rat CA3-CA1 synapses to investigate the contribution of ER. Our model predicts that presynaptic ER is critical in generating the observed short-term plasticity profile of CA3-CA1 synapses and allows synapses with low release probability to operate more reliably. Blocking the ER lowers facilitation in a manner similar to what has been previously characterized in animal models of Alzheimer's disease and underscores the important role played by presynaptic stores in normal function.
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14
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Ma H, Jia B, Li Y, Gu H. Excitability and Threshold Mechanism for Enhanced Neuronal Response Induced by Inhibition Preceding Excitation. Neural Plast 2021; 2021:6692411. [PMID: 33531892 PMCID: PMC7837794 DOI: 10.1155/2021/6692411] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Revised: 12/02/2020] [Accepted: 01/06/2021] [Indexed: 11/18/2022] Open
Abstract
Postinhibitory facilitation (PIF) of neural firing presents a paradoxical phenomenon that the inhibitory effect induces enhancement instead of reduction of the firing activity, which plays important roles in sound location of the auditory nervous system, awaited theoretical explanations. In the present paper, excitability and threshold mechanism for the PIF phenomenon is presented in the Morris-Lecar model with type I, II, and III excitabilities. Firstly, compared with the purely excitatory stimulations applied to the steady state, the inhibitory preceding excitatory stimulation to form pairs induces the firing rate increased for type II and III excitabilities instead of type I excitability, when the interval between the inhibitory and excitatory stimulation within each pair is suitable. Secondly, the threshold mechanism for the PIF phenomenon is acquired. For type II and III excitabilities, the inhibitory stimulation induces subthreshold oscillations around the steady state. During the middle and ending phase of the ascending part and the beginning phase of the descending part within a period of the subthreshold oscillations, the threshold to evoke an action potential by an excitatory stimulation becomes weaker, which is the cause for the PIF phenomenon. Last, a theoretical estimation for the range of the interval between the inhibitory and excitatory stimulation for the PIF phenomenon is acquired, which approximates half of the intrinsic period of the subthreshold oscillations for the relatively strong stimulations and becomes narrower for the relatively weak stimulations. The interval for the PIF phenomenon is much shorter for type III excitability, which is closer to the experiment observation, due to the shorter period of the subthreshold oscillations. The results present the excitability and threshold mechanism for the PIF phenomenon, which provide comprehensive and deep explanations to the PIF phenomenon.
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Affiliation(s)
- Hanqing Ma
- School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092, China
| | - Bing Jia
- School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092, China
| | - Yuye Li
- College of Mathematics and Computer Science, Chifeng University, Chifeng 024000, China
| | - Huaguang Gu
- School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092, China
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15
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Schmutz V, Gerstner W, Schwalger T. Mesoscopic population equations for spiking neural networks with synaptic short-term plasticity. JOURNAL OF MATHEMATICAL NEUROSCIENCE 2020; 10:5. [PMID: 32253526 PMCID: PMC7136387 DOI: 10.1186/s13408-020-00082-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 03/25/2020] [Indexed: 06/07/2023]
Abstract
Coarse-graining microscopic models of biological neural networks to obtain mesoscopic models of neural activities is an essential step towards multi-scale models of the brain. Here, we extend a recent theory for mesoscopic population dynamics with static synapses to the case of dynamic synapses exhibiting short-term plasticity (STP). The extended theory offers an approximate mean-field dynamics for the synaptic input currents arising from populations of spiking neurons and synapses undergoing Tsodyks-Markram STP. The approximate mean-field dynamics accounts for both finite number of synapses and correlation between the two synaptic variables of the model (utilization and available resources) and its numerical implementation is simple. Comparisons with Monte Carlo simulations of the microscopic model show that in both feedforward and recurrent networks, the mesoscopic mean-field model accurately reproduces the first- and second-order statistics of the total synaptic input into a postsynaptic neuron and accounts for stochastic switches between Up and Down states and for population spikes. The extended mesoscopic population theory of spiking neural networks with STP may be useful for a systematic reduction of detailed biophysical models of cortical microcircuits to numerically efficient and mathematically tractable mean-field models.
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Affiliation(s)
- Valentin Schmutz
- Brain Mind Institute, École Polytechnique Féderale de Lausanne (EPFL), Lausanne, Switzerland.
| | - Wulfram Gerstner
- Brain Mind Institute, École Polytechnique Féderale de Lausanne (EPFL), Lausanne, Switzerland
| | - Tilo Schwalger
- Brain Mind Institute, École Polytechnique Féderale de Lausanne (EPFL), Lausanne, Switzerland
- Bernstein Center for Computational Neuroscience, Institut für Mathematik, Technische Universität Berlin, Berlin, Germany
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16
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Bridi MS, Shin S, Huang S, Kirkwood A. Dynamic Recovery from Depression Enables Rate Encoding in Inhibitory Synapses. iScience 2020; 23:100940. [PMID: 32163896 PMCID: PMC7066227 DOI: 10.1016/j.isci.2020.100940] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Revised: 07/18/2019] [Accepted: 02/21/2020] [Indexed: 12/25/2022] Open
Abstract
Parvalbumin-expressing fast-spiking interneurons (PV-INs) control network firing and the gain of cortical response to sensory stimulation. Crucial for these functions, PV-INs can sustain high-frequency firing with no accommodation. However, PV-INs also exhibit short-term depression (STD) during sustained activation, largely due to the depletion of synaptic resources (vesicles). In most synapses the rate of replenishment of depleted vesicles is constant, determining an inverse relationship between depression levels and the activation rate, which theoretically, severely limits rate-coding capabilities. We examined STD of the PV-IN to pyramidal cell synapse in the mouse visual cortex and found that in these synapses the recovery from depression is not constant but increases linearly with the frequency of use. By combining modeling, dynamic clamp, and optogenetics, we demonstrated that this recovery enables PV-INs to reduce pyramidal cell firing in a linear manner, which theoretically is crucial for controlling the gain of cortical visual responses. Recovery rate from depression in inhibitory synapses from PV-INs is use dependent Dynamic recovery from depression enables rate coding in inhibitory inputs PV-IN synapses reduce pyramidal firing in a frequency-dependent manner
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Affiliation(s)
- Morgan S Bridi
- Program in Neuroscience, Hussman Institute for Autism, Baltimore, MD 21201, USA
| | - Sangyep Shin
- Program in Neuroscience, Hussman Institute for Autism, Baltimore, MD 21201, USA
| | - Shiyong Huang
- Program in Neuroscience, Hussman Institute for Autism, Baltimore, MD 21201, USA; The Mind/Brain Institute, Johns Hopkins University, Baltimore, MD 21218, USA.
| | - Alfredo Kirkwood
- The Mind/Brain Institute, Johns Hopkins University, Baltimore, MD 21218, USA; Department of Neuroscience, Johns Hopkins University, Baltimore, MD 21205, USA.
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17
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Zhao Z, Li L, Gu H. Different dynamical behaviors induced by slow excitatory feedback for type II and III excitabilities. Sci Rep 2020; 10:3646. [PMID: 32108168 PMCID: PMC7046675 DOI: 10.1038/s41598-020-60627-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2019] [Accepted: 02/14/2020] [Indexed: 11/13/2022] Open
Abstract
Neuronal excitability is classified as type I, II, or III, according to the responses of electronic activities, which play different roles. In the present paper, the effect of an excitatory autapse on type III excitability is investigated and compared to type II excitability in the Morris-Lecar model, based on Hopf bifurcation and characteristics of the nullcline. The autaptic current of a fast-decay autapse produces periodic stimulations, and that of a slow-decay autapse highly resembles sustained stimulations. Thus, both fast- and slow-decay autapses can induce a resting state for type II excitability that changes to repetitive firing. However, for type III excitability, a fast-decay autapse can induce a resting state to change to repetitive firing, while a slow-decay autapse can induce a resting state to change to a resting state following a transient spike instead of repetitive spiking, which shows the abnormal phenomenon that a stronger excitatory effect of a slow-decay autapse just induces weaker responses. Our results uncover a novel paradoxical phenomenon of the excitatory effect, and we present potential functions of fast- and slow-decay autapses that are helpful for the alteration and maintenance of type III excitability in the real nervous system related to neuropathic pain or sound localization.
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Affiliation(s)
- Zhiguo Zhao
- School of Science, Henan Institute of Technology, Xinxiang, 453003, China
| | - Li Li
- Guangdong Key Laboratory of Modern Control Technology, Guangdong Institute of Intelligent Manufacturing, Guangzhou, 510070, China
| | - Huaguang Gu
- School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai, 200092, China.
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18
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Short-term depression shapes information transmission in a constitutively active GABAergic synapse. Sci Rep 2019; 9:18092. [PMID: 31792286 PMCID: PMC6889381 DOI: 10.1038/s41598-019-54607-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 11/18/2019] [Indexed: 01/21/2023] Open
Abstract
Short-term depression is a low-pass filter of synaptic information, reducing synaptic information transfer at high presynaptic firing frequencies. Consequently, during elevated presynaptic firing, little information passes to the postsynaptic neuron. However, many neurons fire at relatively high frequencies all the time. Does depression silence their synapses? We tested this apparent contradiction in the indirect pathway of the basal ganglia. Using numerical modeling and whole-cell recordings from single entopeduncular nucleus (EP) neurons in rat brain slices, we investigated how different firing rates of globus pallidus (GP) neurons affect information transmission to the EP. Whole-cell recordings showed significant variability in steady-state depression, which decreased as stimulation frequency increased. Modeling predicted that this variability would translate into different postsynaptic noise levels during constitutive presynaptic activity. Our simulations further predicted that individual GP-EP synapses mediate gain control. However, when we consider the integration of multiple inputs, the broad range of GP firing rates would enable different modes of information transmission. Finally, we predict that changes in dopamine levels can shift the action of GP neurons from rate coding to gain modulation. Our results thus demonstrate how short-term depression shapes information transmission in the basal ganglia in particular and via GABAergic synapses in general.
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19
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Malinowski ST, Wolf J, Kuenzel T. Intrinsic and Synaptic Dynamics Contribute to Adaptation in the Core of the Avian Central Nucleus of the Inferior Colliculus. Front Neural Circuits 2019; 13:46. [PMID: 31379514 PMCID: PMC6646678 DOI: 10.3389/fncir.2019.00046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Accepted: 07/01/2019] [Indexed: 11/13/2022] Open
Abstract
The reduction of neuronal responses to repeated stimulus presentation occurs in many sensory neurons, also in the inferior colliculus of birds. The cellular mechanisms that cause response adaptation are not well described. Adaptation must be explicable by changes in the activity of input neurons, short-term synaptic plasticity of the incoming connections, excitability changes of the neuron under consideration or influences of inhibitory or modulatory network connections. Using whole-cell recordings in acute brain slices of the embryonic chicken brain we wanted to understand the intrinsic and synaptic contributions to adaptation in the core of the central nucleus of the inferior colliculus (ICCc). We described two neuron types in the chicken ICCc based on their action potential firing patterns: Phasic/onset neurons showed strong intrinsic adaptation but recovered more rapidly. Tonic/sustained firing neurons had weaker adaptation but often had additional slow components of recovery from adaptation. Morphological analysis suggested two neuron classes, but no physiological parameter aligned with this classification. Chicken ICCc neurons received mostly mixed AMPA- and NMDA-type glutamatergic synaptic inputs. In the majority of ICCc neurons the input synapses underwent short-term depression. With a simulation of the putative population output activity of the chicken ICCc we showed that the different adaptation profiles of the neuron classes could shift the emphasize of stimulus encoding from transients at long intervals to ongoing parts at short intervals. Thus, we report here that description of biophysical and synaptic properties can help to explain adaptive phenomena in central auditory neurons.
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Affiliation(s)
- Sebastian T Malinowski
- Auditory Neurophysiology Group, Department of Chemosensation, RWTH Aachen University, Aachen, Germany.,Department of Chemosensation, RWTH Aachen University, Aachen, Germany
| | - Jana Wolf
- Auditory Neurophysiology Group, Department of Chemosensation, RWTH Aachen University, Aachen, Germany
| | - Thomas Kuenzel
- Auditory Neurophysiology Group, Department of Chemosensation, RWTH Aachen University, Aachen, Germany
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20
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Kitagawa M, Sakaba T. Developmental changes in the excitatory short‐term plasticity at input synapses in the rat inferior colliculus. Eur J Neurosci 2019; 50:2830-2846. [DOI: 10.1111/ejn.14422] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 03/28/2019] [Accepted: 04/04/2019] [Indexed: 11/29/2022]
Affiliation(s)
- Mako Kitagawa
- Graduate School of Brain Science Doshisha University Kyoto Japan
| | - Takeshi Sakaba
- Graduate School of Brain Science Doshisha University Kyoto Japan
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21
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McColgan T, Kuokkanen PT, Carr CE, Kempter R. Dynamics of synaptic extracellular field potentials in the nucleus laminaris of the barn owl. J Neurophysiol 2019; 121:1034-1047. [PMID: 30575430 DOI: 10.1152/jn.00648.2017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Synaptic currents are frequently assumed to make a major contribution to the extracellular field potential (EFP). However, in any neuronal population, the explicit separation of synaptic sources from other contributions such as postsynaptic spikes remains a challenge. Here we take advantage of the simple organization of the barn owl nucleus laminaris (NL) in the auditory brain stem to isolate synaptic currents through the iontophoretic application of the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-receptor antagonist 1,2,3,4-tetrahydro-6-nitro-2,3-dioxo-benzo[ f]quinoxaline-7-sulfonamide (NBQX). Responses to auditory stimulation show that the temporal dynamics of the evoked synaptic contributions to the EFP are consistent with synaptic short-term depression (STD). The estimated time constants of an STD model fitted to the data are similar to the fast time constants reported from in vitro experiments in the chick. Overall, the putative synaptic EFPs in the barn owl NL are significant but small (<1% change of the variance by NBQX). This result supports the hypothesis that the EFP in NL is generated mainly by axonal spikes, in contrast to most other neuronal systems. NEW & NOTEWORTHY Synaptic currents are assumed to make a major contribution to the extracellular field potential in the brain, but it is hard to directly isolate these synaptic components. Here we take advantage of the simple organization of the barn owl nucleus laminaris in the auditory brain stem to isolate synaptic currents through the iontophoretic application of a synaptic blocker. We show that the responses are consistent with a simple model of short-term synaptic depression.
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Affiliation(s)
- Thomas McColgan
- Bernstein Center for Computational Neuroscience , Berlin , Germany.,Institute for Theoretical Biology, Department of Biology, Humboldt-Universität zu Berlin, Berlin , Germany
| | - Paula T Kuokkanen
- Bernstein Center for Computational Neuroscience , Berlin , Germany.,Institute for Theoretical Biology, Department of Biology, Humboldt-Universität zu Berlin, Berlin , Germany.,Department of Biology, University of Maryland , College Park, Maryland
| | - Catherine E Carr
- Department of Biology, University of Maryland , College Park, Maryland
| | - Richard Kempter
- Bernstein Center for Computational Neuroscience , Berlin , Germany.,Institute for Theoretical Biology, Department of Biology, Humboldt-Universität zu Berlin, Berlin , Germany.,Einstein Center for Neurosciences , Berlin , Germany
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22
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Motanis H, Seay MJ, Buonomano DV. Short-Term Synaptic Plasticity as a Mechanism for Sensory Timing. Trends Neurosci 2018; 41:701-711. [PMID: 30274605 DOI: 10.1016/j.tins.2018.08.001] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 07/18/2018] [Accepted: 08/01/2018] [Indexed: 11/25/2022]
Abstract
The ability to detect time intervals and temporal patterns is critical to some of the most fundamental computations the brain performs, including the ability to communicate and appraise a dynamically changing environment. Many of these computations take place on the scale of tens to hundreds of milliseconds. Electrophysiological evidence shows that some neurons respond selectively to duration, interval, rate, or order. Because the time constants of many time-varying neural and synaptic properties, including short-term synaptic plasticity (STP), are also in the range of tens to hundreds of milliseconds, they are strong candidates to underlie the formation of temporally selective neurons. Neurophysiological studies indicate that STP is indeed one of the mechanisms that contributes to temporal selectivity, and computational models demonstrate that neurons embedded in local microcircuits exhibit temporal selectivity if their synapses undergo STP. Converging evidence suggests that some forms of temporal selectivity emerge from the dynamic changes in the balance of excitation and inhibition imposed by STP.
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Affiliation(s)
- Helen Motanis
- Integrative Center for Learning & Memory, Departments of Neurobiology and Psychology, UCLA, Los Angeles, CA, 90095, USA; These authors contributed equally to the paper
| | - Michael J Seay
- Integrative Center for Learning & Memory, Departments of Neurobiology and Psychology, UCLA, Los Angeles, CA, 90095, USA; These authors contributed equally to the paper
| | - Dean V Buonomano
- Integrative Center for Learning & Memory, Departments of Neurobiology and Psychology, UCLA, Los Angeles, CA, 90095, USA.
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23
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Castillo AE, Rossoni S, Niven JE. Matched Short-Term Depression and Recovery Encodes Interspike Interval at a Central Synapse. Sci Rep 2018; 8:13629. [PMID: 30206296 PMCID: PMC6134063 DOI: 10.1038/s41598-018-31996-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Accepted: 08/20/2018] [Indexed: 11/20/2022] Open
Abstract
Reversible decreases in synaptic strength, known as short-term depression (STD), are widespread in neural circuits. Various computational roles have been attributed to STD but these tend to focus upon the initial depression rather than the subsequent recovery. We studied the role of STD and recovery at an excitatory synapse between the fast extensor tibiae (FETi) and flexor tibiae (flexor) motor neurons in the desert locust (Schistocerca gregaria) by making paired intracellular recordings in vivo. Over behaviorally relevant pre-synaptic spike frequencies, we found that this synapse undergoes matched frequency-dependent STD and recovery; higher frequency spikes that evoke stronger, faster STD also produce stronger, faster recovery. The precise matching of depression and recovery time constants at this synapse ensures that flexor excitatory post-synaptic potential (EPSP) amplitude encodes the presynaptic FETi interspike interval (ISI). Computational modelling shows that this precise matching enables the FETi-flexor synapse to linearly encode the ISI in the EPSP amplitude, a coding strategy that may be widespread in neural circuits.
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Affiliation(s)
- Armando E Castillo
- School of Life Sciences and Centre for Computational Neuroscience and Robotics, University of Sussex, Falmer, Brighton, BN1 9QG, UK. .,Centro de Neurociencias, Instituto de Investigaciones Científicas y Servicios de Alta Tecnología, Ciudad de Saber, Republic of Panama.
| | - Sergio Rossoni
- School of Life Sciences and Centre for Computational Neuroscience and Robotics, University of Sussex, Falmer, Brighton, BN1 9QG, UK.,Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge, CB2 3EJ, UK
| | - Jeremy E Niven
- School of Life Sciences and Centre for Computational Neuroscience and Robotics, University of Sussex, Falmer, Brighton, BN1 9QG, UK.
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24
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Lu Y, Liu Y, Curry RJ. Activity-dependent synaptic integration and modulation of bilateral excitatory inputs in an auditory coincidence detection circuit. J Physiol 2018; 596:1981-1997. [PMID: 29572827 DOI: 10.1113/jp275735] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Accepted: 03/05/2018] [Indexed: 02/05/2023] Open
Abstract
KEY POINTS Binaural excitatory inputs to coincidence detection neurons in nucleus laminaris (NL) play essential roles in interaural time difference coding for sound localization. Here, we show that the two excitatory inputs are physiologically nearly completely segregated. Synaptic integration shows linear summation of EPSPs, ensuring high efficiency of coincidence detection of the bilateral excitatory inputs. We further show that the two excitatory inputs to single NL neurons are symmetrical in synaptic strength, kinetics and short-term plasticity. Modulation of the EPSCs by metabotropic glutamate receptors (mGluRs) is identical between the two excitatory inputs, maintaining balanced bilateral excitation under neuromodulatory conditions. Unilateral hearing deprivation reduces synaptic excitation and paradoxically strengthens mGluR modulation of EPSCs, suggesting activity-dependent anti-homeostatic regulation, a novel synaptic plasticity in response to sensory manipulations. ABSTRACT Neurons in the avian nucleus laminaris (NL) receive bilateral excitatory inputs from the cochlear nucleus magnocellularis, via morphologically symmetrical dorsal (ipsilateral) and ventral (contralateral) dendrites. Using in vitro whole-cell patch recordings in chicken brainstem slices, we investigated synaptic integration and modulation of the bilateral inputs to NL under normal and hearing deprivation conditions. We found that the two excitatory inputs onto single NL neurons were nearly completely segregated, and integration of the two inputs was linear for EPSPs. The two inputs had similar synaptic strength, kinetics and short-term plasticity. EPSCs in low but not middle and high frequency neurons were suppressed by activation of group I and II metabotropic glutamate receptors (mGluR I and II), with similar modulatory strength between the ipsilateral and contralateral inputs. Unilateral hearing deprivation by cochlea removal reduced the excitatory transmission on the deprived dendritic domain of NL. Interestingly, EPSCs evoked at the deprived domain were modulated more strongly by mGluR II than at the counterpart domain that received intact input in low frequency neurons, suggesting anti-homeostatic regulation. This was supported by a stronger expression of mGluR II protein on the deprived neuropils of NL. Under mGluR II modulation, EPSCs on the deprived input show transient synaptic facilitation, forming a striking contrast with normal hearing conditions under which pure synaptic depression is observed. These results demonstrate physiological symmetry and thus balanced bilateral excitatory inputs to NL neurons. The activity-dependent anti-homeostatic plasticity of mGluR modulation constitutes a novel mechanism regulating synaptic transmission in response to sensory input manipulations.
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Affiliation(s)
- Yong Lu
- Hearing Research Group, Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH, 44272, USA.,School of Biomedical Sciences, Kent State University, Kent, OH, 44240, USA
| | - Yuwei Liu
- Hearing Research Group, Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH, 44272, USA
| | - Rebecca J Curry
- Hearing Research Group, Department of Anatomy and Neurobiology, College of Medicine, Northeast Ohio Medical University, Rootstown, OH, 44272, USA.,School of Biomedical Sciences, Kent State University, Kent, OH, 44240, USA
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Synaptotagmin 7 confers frequency invariance onto specialized depressing synapses. Nature 2017; 551:503-506. [PMID: 29088700 PMCID: PMC5892411 DOI: 10.1038/nature24474] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Accepted: 10/09/2017] [Indexed: 12/22/2022]
Abstract
At most synapses in the brain, short-term plasticity dynamically modulates synaptic strength. Rapid frequency-dependent changes in synaptic strength play critical roles in sensory adaptation, gain control and many other neural computations1,2. However, some auditory, vestibular and cerebellar synapses maintain constant strength over a wide range of firing frequencies3–5, and as a result efficiently encode firing rates. Despite its apparent simplicity, frequency-invariant transmission is difficult to achieve because of inherent synaptic nonlinearities6. Here we study frequency-invariant transmission at Purkinje cell to deep cerebellar nuclear (PC to DCN) synapses and vestibular synapses. Prolonged activation of these synapses leads to initial depression, which is followed by steady-state responses that are frequency invariant for their physiological activity range. We find that Synaptotagmin 7 (Syt7), a recently identified calcium sensor for short-term facilitation7, is present at both synapses. It was unclear why a sensor for facilitation would be present at these and other depressing synapses. We find that at PC and vestibular synapses, Syt7 supports a hidden component of facilitation that can be unmasked in wildtype animals but is absent in Syt7 knockout animals. In wildtype mice, facilitation increases with firing frequency and counteracts depression to produce frequency-invariant transmission. In Syt7 knockout mice, PC and vestibular synapses exhibit conventional use-dependent depression, weakening to a greater extent as the firing frequency is increased. Presynaptic rescue of Syt7 expression restores both facilitation and frequency-invariant transmission. Our results identify a function for Syt7 at synapses that exhibit overall depression, and demonstrate that facilitation plays an unexpected and important role in producing frequency-invariant transmission.
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26
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Silva AJD, Floquet S, Santos DOC. Statistical crossover and nonextensive behavior of neuronal short-term depression. J Biol Phys 2017; 44:37-50. [PMID: 29027614 DOI: 10.1007/s10867-017-9474-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 09/20/2017] [Indexed: 12/27/2022] Open
Abstract
The theoretical basis of neuronal coding, associated with short-term degradation in synaptic transmission, is a matter of debate in the literature. In fact, electrophysiological signals are commonly characterized as inversely proportional to stimulus intensity. Among theoretical descriptions of this phenomenon, models based on 1/f-dependency are employed to investigate the biophysical properties of short-term synaptic depression. In this work, we formulate a model based on a paradigmatic q-differential equation to obtain a generalized formalism useful for investigation of nonextensivity in this specific type of synaptic plasticity. Our analysis reveals nonextensivity in data from electrophysiological recordings and also a statistical crossover in neurotransmission. In particular, statistical transitions provide additional support to the hypothesis of heterogeneous release probability of neurotransmitters. On the other hand, the simple vesicle model agrees with data only at low-frequency stimulations. Thus, the present work presents a method to demonstrate that short-term depression is not only governed by random mechanisms but also by nonextensive behavior. Our findings also conciliate morphological and electrophysiological investigations into a coherent biophysical scenario.
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Affiliation(s)
- A J da Silva
- Centro de Formação em Ciências e Tecnologias Agroflorestais, Universidade Federal do Sul da Bahia, Itabuna, Bahia. CEP 45613-204, Brazil.
| | - S Floquet
- Colegiado de Engenharia Civil, Universidade Federal do Vale do São Francisco, Juazeiro, Bahia. CEP 48902-300, Brazil
| | - D O C Santos
- Centro de Formação em Ciências e Tecnologias Agroflorestais, Universidade Federal do Sul da Bahia, Itabuna, Bahia. CEP 45613-204, Brazil
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27
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McDonnell MD, Graham BP. Phase changes in neuronal postsynaptic spiking due to short term plasticity. PLoS Comput Biol 2017; 13:e1005634. [PMID: 28937977 PMCID: PMC5627952 DOI: 10.1371/journal.pcbi.1005634] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 10/04/2017] [Accepted: 06/08/2017] [Indexed: 02/03/2023] Open
Abstract
In the brain, the postsynaptic response of a neuron to time-varying inputs is determined by the interaction of presynaptic spike times with the short-term dynamics of each synapse. For a neuron driven by stochastic synapses, synaptic depression results in a quite different postsynaptic response to a large population input depending on how correlated in time the spikes across individual synapses are. Here we show using both simulations and mathematical analysis that not only the rate but the phase of the postsynaptic response to a rhythmic population input varies as a function of synaptic dynamics and synaptic configuration. Resultant phase leads may compensate for transmission delays and be predictive of rhythmic changes. This could be particularly important for sensory processing and motor rhythm generation in the nervous system. The synapses that connect neurons in the brain are far from being simple relay points that pass a signal from one neuron to another. There is now much evidence that long term changes in the strength of such connections, which determines the amplitude of the received signal, underpin learning and memory in the brain. However, signal amplitudes also fluctuate on fast time scales of milliseconds to seconds due to a variety of particular presynaptic mechanisms that regulate the release of neurotransmitter from the presynaptic terminal. Understanding the signal filtering properties of this short-term plasticity (STP) is a challenge and requires theoretical models. Aspects such as rate filtering and information transfer have been studied. Here we explore the effects of STP on the phase of a receiving neuron’s response to oscillating input and show that short-term depression can result in a frequency-dependent phase lead. This may be particularly important in the processing of rhythmic visual and auditory signals and producing rhythmic motor outputs.
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Affiliation(s)
- Mark D. McDonnell
- Computational Learning Systems Laboratory, School of Information Technology and Mathematical Sciences, University of South Australia, Mawson Lakes, Australia
- * E-mail: (MDM); (BPG)
| | - Bruce P. Graham
- Computing Science & Mathematics, Faculty of Natural Sciences, University of Stirling, Stirling, United Kingdom
- * E-mail: (MDM); (BPG)
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Santos FP, Maciel CD, Newland PL. Pre-processing and transfer entropy measures in motor neurons controlling limb movements. J Comput Neurosci 2017; 43:159-171. [PMID: 28791522 DOI: 10.1007/s10827-017-0656-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 07/24/2017] [Accepted: 07/25/2017] [Indexed: 10/19/2022]
Abstract
Directed information transfer measures are increasingly being employed in modeling neural system behavior due to their model-free approach, applicability to nonlinear and stochastic signals, and the potential to integrate repetitions of an experiment. Intracellular physiological recordings of graded synaptic potentials provide a number of additional challenges compared to spike signals due to non-stationary behaviour generated through extrinsic processes. We therefore propose a method to overcome this difficulty by using a preprocessing step based on Singular Spectrum Analysis (SSA) to remove nonlinear trends and discontinuities. We apply the method to intracellular recordings of synaptic responses of identified motor neurons evoked by stimulation of a proprioceptor that monitors limb position in leg of the desert locust. We then apply normalized delayed transfer entropy measures to neural responses evoked by displacements of the proprioceptor, the femoral chordotonal organ, that contains sensory neurones that monitor movements about the femoral-tibial joint. We then determine the consistency of responses within an individual recording of an identified motor neuron in a single animal, between repetitions of the same experiment in an identified motor neurons in the same animal and in repetitions of the same experiment from the same identified motor neuron in different animals. We found that delayed transfer entropy measures were consistent for a given identified neuron within and between animals and that they predict neural connectivity for the fast extensor tibiae motor neuron.
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Affiliation(s)
- Fernando P Santos
- Faculty of Electrical Engineering, Federal University of Uberlândia, Av. João Naves de Ávila, 2160, Bloco 3N, Uberlândia, 38408-100, MG, Brazil. .,Signal Processing Laboratory, Department of Electrical Engineering, University of São Paulo, Av. Trabalhador Sãocarlense, 400, São Carlos, 13566-590, SP, Brazil.
| | - Carlos D Maciel
- Faculty of Electrical Engineering, Federal University of Uberlândia, Av. João Naves de Ávila, 2160, Bloco 3N, Uberlândia, 38408-100, MG, Brazil
| | - Philip L Newland
- Biological Sciences, University of Southampton, Highfield Campus, Southampton, S017 1BJ, UK
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Jackman SL, Regehr WG. The Mechanisms and Functions of Synaptic Facilitation. Neuron 2017; 94:447-464. [PMID: 28472650 DOI: 10.1016/j.neuron.2017.02.047] [Citation(s) in RCA: 238] [Impact Index Per Article: 34.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Revised: 02/23/2017] [Accepted: 02/28/2017] [Indexed: 12/22/2022]
Abstract
The ability of the brain to store and process information relies on changing the strength of connections between neurons. Synaptic facilitation is a form of short-term plasticity that enhances synaptic transmission for less than a second. Facilitation is a ubiquitous phenomenon thought to play critical roles in information transfer and neural processing. Yet our understanding of the function of facilitation remains largely theoretical. Here we review proposed roles for facilitation and discuss how recent progress in uncovering the underlying molecular mechanisms could enable experiments that elucidate how facilitation, and short-term plasticity in general, contributes to circuit function and animal behavior.
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Affiliation(s)
- Skyler L Jackman
- Department of Neurobiology, Harvard Medical School, Boston, MA 02118, USA
| | - Wade G Regehr
- Department of Neurobiology, Harvard Medical School, Boston, MA 02118, USA.
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30
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Rudnicki M, Hemmert W. High Entrainment Constrains Synaptic Depression Levels of an In vivo Globular Bushy Cell Model. Front Comput Neurosci 2017; 11:16. [PMID: 28373839 PMCID: PMC5357671 DOI: 10.3389/fncom.2017.00016] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 03/02/2017] [Indexed: 12/15/2022] Open
Abstract
Globular bushy cells (GBCs) located in the ventral cochlear nucleus are an essential part of the sound localization pathway in the mammalian auditory system. They receive inputs directly from the auditory nerve and are particularly sensitive to temporal cues due to their synaptic and membrane specializations. GBCs act as coincidence detectors for incoming spikes through large synapses-endbulbs of Held-which connect to their soma. Since endbulbs of Held are an integral part of the auditory information conveying and processing pathway, they were extensively studied. Virtually all in vitro studies showed large synaptic depression, but on the other hand a few in vivo studies showed relatively small depression. It is also still not well understood how synaptic properties functionally influence firing properties of GBCs. Here we show how different levels of synaptic depression shape firing properties of GBCs in in vivo-like conditions using computer simulations. We analyzed how an interplay of synaptic depression (0-70%) and the number of auditory nerve fiber inputs (10-70) contributes to the variability of the experimental data from previous studies. We predict that the majority of synapses of GBCs with high characteristic frequencies (CF > 500 Hz) have a rate dependent depression of less than 20%. GBCs with lower CF (<500 Hz) work also with strong depressing synapses (up to 50% or more). We also showed that synapses explicitly fitted to in vitro experiments with paired-pulse stimuli did not operate properly in in vivo-like conditions and required further extension to capture the differences between in vitro and in vivo experimental conditions. Overall, this study helps to understand how synaptic properties shape temporal processing in the auditory system. It also integrates, compares, and reconciles results of various experimental studies.
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Affiliation(s)
- Marek Rudnicki
- Bio-Inspired Information Processing, Technische Universität München München, Germany
| | - Werner Hemmert
- Bio-Inspired Information Processing, Technische Universität München München, Germany
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31
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Mukunda CL, Narayanan R. Degeneracy in the regulation of short-term plasticity and synaptic filtering by presynaptic mechanisms. J Physiol 2017; 595:2611-2637. [PMID: 28026868 DOI: 10.1113/jp273482] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 12/13/2016] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS We develop a new biophysically rooted, physiologically constrained conductance-based synaptic model to mechanistically account for short-term facilitation and depression, respectively through residual calcium and transmitter depletion kinetics. We address the specific question of how presynaptic components (including voltage-gated ion channels, pumps, buffers and release-handling mechanisms) and interactions among them define synaptic filtering and short-term plasticity profiles. Employing global sensitivity analyses (GSAs), we show that near-identical synaptic filters and short-term plasticity profiles could emerge from disparate presynaptic parametric combinations with weak pairwise correlations. Using virtual knockout models, a technique to address the question of channel-specific contributions within the GSA framework, we unveil the differential and variable impact of each ion channel on synaptic physiology. Our conclusions strengthen the argument that parametric and interactional complexity in biological systems should not be viewed from the limited curse-of-dimensionality standpoint, but from the evolutionarily advantageous perspective of providing functional robustness through degeneracy. ABSTRACT Information processing in neurons is known to emerge as a gestalt of pre- and post-synaptic filtering. However, the impact of presynaptic mechanisms on synaptic filters has not been quantitatively assessed. Here, we developed a biophysically rooted, conductance-based model synapse that was endowed with six different voltage-gated ion channels, calcium pumps, calcium buffer and neurotransmitter-replenishment mechanisms in the presynaptic terminal. We tuned our model to match the short-term plasticity profile and band-pass structure of Schaffer collateral synapses, and performed sensitivity analyses to demonstrate that presynaptic voltage-gated ion channels regulated synaptic filters through changes in excitability and associated calcium influx. These sensitivity analyses also revealed that calcium- and release-control mechanisms were effective regulators of synaptic filters, but accomplished this without changes in terminal excitability or calcium influx. Next, to perform global sensitivity analysis, we generated 7000 randomized models spanning 15 presynaptic parameters, and computed eight different physiological measurements in each of these models. We validated these models by applying experimentally obtained bounds on their measurements, and found 104 (∼1.5%) models to match the validation criteria for all eight measurements. Analysing these valid models, we demonstrate that analogous synaptic filters emerge from disparate combinations of presynaptic parameters exhibiting weak pairwise correlations. Finally, using virtual knockout models, we establish the variable and differential impact of different presynaptic channels on synaptic filters, underlining the critical importance of interactions among different presynaptic components in defining synaptic physiology. Our results have significant implications for protein-localization strategies required for physiological robustness and for degeneracy in long-term synaptic plasticity profiles.
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Affiliation(s)
- Chinmayee L Mukunda
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
| | - Rishikesh Narayanan
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India
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32
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Anwar H, Li X, Bucher D, Nadim F. Functional roles of short-term synaptic plasticity with an emphasis on inhibition. Curr Opin Neurobiol 2017; 43:71-78. [PMID: 28122326 DOI: 10.1016/j.conb.2017.01.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 01/05/2017] [Accepted: 01/06/2017] [Indexed: 11/16/2022]
Abstract
Almost all synapses show activity-dependent dynamic changes in efficacy. Numerous studies have explored the mechanisms underlying different forms of short-term synaptic plasticity (STP), but the functional role of STP for circuit output and animal behavior is less understood. This is particularly true for inhibitory synapses that can play widely varied roles in circuit activity. We review recent findings on the role of synaptic STP in sensory, pattern generating, thalamocortical, and hippocampal networks, with a focus on synaptic inhibition. These studies show a variety of functions including sensory adaptation and gating, dynamic gain control and rhythm generation. Because experimental manipulations of STP are difficult and nonspecific, a clear demonstration of STP function often requires a combination of experimental and computational techniques.
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Affiliation(s)
- Haroon Anwar
- Federated Department of Biological Sciences, New Jersey Institute of Technology and Rutgers University, 323 Martin Luther King Blvd, Newark, NJ 07102, United States
| | - Xinping Li
- Federated Department of Biological Sciences, New Jersey Institute of Technology and Rutgers University, 323 Martin Luther King Blvd, Newark, NJ 07102, United States
| | - Dirk Bucher
- Federated Department of Biological Sciences, New Jersey Institute of Technology and Rutgers University, 323 Martin Luther King Blvd, Newark, NJ 07102, United States
| | - Farzan Nadim
- Federated Department of Biological Sciences, New Jersey Institute of Technology and Rutgers University, 323 Martin Luther King Blvd, Newark, NJ 07102, United States.
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33
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Turecek J, Jackman SL, Regehr WG. Synaptic Specializations Support Frequency-Independent Purkinje Cell Output from the Cerebellar Cortex. Cell Rep 2016; 17:3256-3268. [PMID: 28009294 PMCID: PMC5870134 DOI: 10.1016/j.celrep.2016.11.081] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 11/14/2016] [Accepted: 11/28/2016] [Indexed: 11/23/2022] Open
Abstract
The output of the cerebellar cortex is conveyed to the deep cerebellar nuclei (DCN) by Purkinje cells (PCs). Here, we characterize the properties of the PC-DCN synapse in juvenile and adult mice and find that prolonged high-frequency stimulation leads to steady-state responses that become increasingly frequency independent within the physiological firing range of PCs in older animals, resulting in a linear relationship between charge transfer and activation frequency. We used a low-affinity antagonist to show that GABAA-receptor saturation occurs at this synapse but does not underlie frequency-invariant transmission. We propose that PC-DCN synapses have two components of release: one prominent early in trains and another specialized to maintain transmission during prolonged activation. Short-term facilitation offsets partial vesicle depletion to produce frequency-independent transmission.
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Affiliation(s)
- Josef Turecek
- Department of Neurobiology, Harvard Medical School, 220 Longwood Ave., Boston, MA 02115, USA
| | - Skyler L Jackman
- Department of Neurobiology, Harvard Medical School, 220 Longwood Ave., Boston, MA 02115, USA
| | - Wade G Regehr
- Department of Neurobiology, Harvard Medical School, 220 Longwood Ave., Boston, MA 02115, USA.
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34
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Hass CA, Glickfeld LL. High-fidelity optical excitation of cortico-cortical projections at physiological frequencies. J Neurophysiol 2016; 116:2056-2066. [PMID: 27489370 DOI: 10.1152/jn.00456.2016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 08/02/2016] [Indexed: 11/22/2022] Open
Abstract
Optogenetic activation of axons is a powerful approach for determining the synaptic properties and impact of long-range projections both in vivo and in vitro. However, because of the difficulty of measuring activity in axons, our knowledge of the reliability of optogenetic axonal stimulation has relied on data from somatic recordings. Yet, there are many reasons why activation of axons may not be comparable to cell bodies. Thus we have developed an approach to more directly assess the fidelity of optogenetic activation of axonal projections. We expressed opsins (ChR2, Chronos, or oChIEF) in the mouse primary visual cortex (V1) and recorded extracellular, pharmacologically isolated presynaptic action potentials in response to axonal activation in the higher visual areas. Repetitive stimulation of axons with ChR2 resulted in a 70% reduction in the fiber volley amplitude and a 60% increase in the latency at all frequencies tested (10-40 Hz). Thus ChR2 cannot reliably recruit axons during repetitive stimulation, even at frequencies that are reliable for somatic stimulation, likely due to pronounced channel inactivation at the high light powers required to evoke action potentials. By comparison, oChIEF and Chronos evoked photocurrents that inactivated minimally and could produce reliable axon stimulation at frequencies up to 60 Hz. Our approach provides a more direct and accurate evaluation of the efficacy of new optogenetic tools and has identified Chronos and oChIEF as viable tools to interrogate the synaptic and circuit function of long-range projections.
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Affiliation(s)
- Charles A Hass
- Department of Neurobiology, Duke University, Durham, North Carolina
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Abstract
UNLABELLED Many neurons fire spontaneously, and the rate of this firing is subject to neuromodulation. How this firing affects functional connectivity within a neural network remains largely unexplored. Here we show that changes in spontaneous firing of cartwheel interneurons in the mouse dorsal cochlear nucleus (DCN) alter the effective convergence ratio of interneurons onto their postsynaptic targets through short-term synaptic plasticity. Spontaneous firing of cartwheel cells led to activity-dependent synaptic depression of individual cartwheel synapses. Depression was rapid and profound at stimulation frequencies between 10 and 200 Hz, suggesting the presence of high release probability (Pr) vesicles at these inhibitory synapses. Weak, transient synaptic facilitation could be induced after synapses were predepressed, indicating that low-Pr vesicles are also recruited, and may thus support steady-state transmission. A two-pool vesicle depletion model with 10-fold differences in Pr could account for the synaptic depression over a wide range of stimulus conditions. As a result of depression during high spontaneous activity, more cartwheel interneurons were required for effective inhibition. Convergence of four interneurons was sufficient to compensate for the effects of depression during physiologically expected rates of activity. By simulating synaptic release during spontaneous firing, we found that recruitment of low-Pr vesicles at the synapse plays a critical role in maintaining effective inhibition within a small population of interneurons. The interplay between spontaneous spiking, short-term synaptic plasticity, and vesicle recruitment thus determines the effective size of a convergent neural network. SIGNIFICANCE STATEMENT We examined the relationship between the structure of a small neural circuit and the properties of its individual synapses. Successful synaptic inhibition of a target cell firing requires a critical inhibitory synaptic strength. Synapses often become depressed during spontaneous presynaptic activity, and this increases the number of presynaptic neurons needed to mediate inhibition. We show that depression is limited by the presence of a pool of vesicles that resist depletion. Thus, the size of this vesicle pool determines the size of the circuit needed to mediate inhibition during different patterns of activity.
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Superpriming of synaptic vesicles as a common basis for intersynapse variability and modulation of synaptic strength. Proc Natl Acad Sci U S A 2016; 113:E4548-57. [PMID: 27432975 DOI: 10.1073/pnas.1606383113] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Glutamatergic synapses show large variations in strength and short-term plasticity (STP). We show here that synapses displaying an increased strength either after posttetanic potentiation (PTP) or through activation of the phospholipase-C-diacylglycerol pathway share characteristic properties with intrinsically strong synapses, such as (i) pronounced short-term depression (STD) during high-frequency stimulation; (ii) a conversion of that STD into a sequence of facilitation followed by STD after a few conditioning stimuli at low frequency; (iii) an equalizing effect of such conditioning stimulation, which reduces differences among synapses and abolishes potentiation; and (iv) a requirement of long periods of rest for reconstitution of the original STP pattern. These phenomena are quantitatively described by assuming that a small fraction of "superprimed" synaptic vesicles are in a state of elevated release probability (p ∼ 0.5). This fraction is variable in size among synapses (typically about 30%), but increases after application of phorbol ester or during PTP. The majority of vesicles, released during repetitive stimulation, have low release probability (p ∼ 0.1), are relatively uniform in number across synapses, and are rapidly recruited. In contrast, superprimed vesicles need several seconds to be regenerated. They mediate enhanced synaptic strength at the onset of burst-like activity, the impact of which is subject to modulation by slow modulatory transmitter systems.
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37
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Sanchez JT, Quinones K, Otto-Meyer S. Factors Influencing Short-term Synaptic Plasticity in the Avian Cochlear Nucleus Magnocellularis. J Exp Neurosci 2015; 9:11-24. [PMID: 26527054 PMCID: PMC4620996 DOI: 10.4137/jen.s25472] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 09/20/2015] [Accepted: 09/21/2015] [Indexed: 11/15/2022] Open
Abstract
Defined as reduced neural responses during high rates of activity, synaptic depression is a form of short-term plasticity important for the temporal filtering of sound. In the avian cochlear nucleus magnocellularis (NM), an auditory brainstem structure, mechanisms regulating short-term synaptic depression include pre-, post-, and extrasynaptic factors. Using varied paired-pulse stimulus intervals, we found that the time course of synaptic depression lasts up to four seconds at late-developing NM synapses. Synaptic depression was largely reliant on exogenous Ca2+-dependent probability of presynaptic neurotransmitter release, and to a lesser extent, on the desensitization of postsynaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid-type glutamate receptor (AMPA-R). Interestingly, although extrasynaptic glutamate clearance did not play a significant role in regulating synaptic depression, blocking glutamate clearance at early-developing synapses altered synaptic dynamics, changing responses from depression to facilitation. These results suggest a developmental shift in the relative reliance on pre-, post-, and extrasynaptic factors in regulating short-term synaptic plasticity in NM.
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Affiliation(s)
- Jason Tait Sanchez
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, The Hugh Knowles Hearing Research Center, School of Communication, Northwestern University, Evanston, IL, USA. ; Department of Neurobiology and Interdepartmental Neuroscience Program, Northwestern University, Evanston, IL, USA
| | - Karla Quinones
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, The Hugh Knowles Hearing Research Center, School of Communication, Northwestern University, Evanston, IL, USA
| | - Sebastian Otto-Meyer
- Weinberg College of Arts and Sciences, Northwestern University, Evanston, IL, USA
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38
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Synaptic plasticity in the auditory system: a review. Cell Tissue Res 2015; 361:177-213. [PMID: 25896885 DOI: 10.1007/s00441-015-2176-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 03/18/2015] [Indexed: 01/19/2023]
Abstract
Synaptic transmission via chemical synapses is dynamic, i.e., the strength of postsynaptic responses may change considerably in response to repeated synaptic activation. Synaptic strength is increased during facilitation, augmentation and potentiation, whereas a decrease in synaptic strength is characteristic for depression and attenuation. This review attempts to discuss the literature on short-term and long-term synaptic plasticity in the auditory brainstem of mammals and birds. One hallmark of the auditory system, particularly the inner ear and lower brainstem stations, is information transfer through neurons that fire action potentials at very high frequency, thereby activating synapses >500 times per second. Some auditory synapses display morphological specializations of the presynaptic terminals, e.g., calyceal extensions, whereas other auditory synapses do not. The review focuses on short-term depression and short-term facilitation, i.e., plastic changes with durations in the millisecond range. Other types of short-term synaptic plasticity, e.g., posttetanic potentiation and depolarization-induced suppression of excitation, will be discussed much more briefly. The same holds true for subtypes of long-term plasticity, like prolonged depolarizations and spike-time-dependent plasticity. We also address forms of plasticity in the auditory brainstem that do not comprise synaptic plasticity in a strict sense, namely short-term suppression, paired tone facilitation, short-term adaptation, synaptic adaptation and neural adaptation. Finally, we perform a meta-analysis of 61 studies in which short-term depression (STD) in the auditory system is opposed to short-term depression at non-auditory synapses in order to compare high-frequency neurons with those that fire action potentials at a lower rate. This meta-analysis reveals considerably less STD in most auditory synapses than in non-auditory ones, enabling reliable, failure-free synaptic transmission even at frequencies >100 Hz. Surprisingly, the calyx of Held, arguably the best-investigated synapse in the central nervous system, depresses most robustly. It will be exciting to reveal the molecular mechanisms that set high-fidelity synapses apart from other synapses that function much less reliably.
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García-Pérez E, Mahfooz K, Covita J, Zandueta A, Wesseling JF. Levetiracetam accelerates the onset of supply rate depression in synaptic vesicle trafficking. Epilepsia 2015; 56:535-45. [PMID: 25684406 DOI: 10.1111/epi.12930] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/31/2014] [Indexed: 11/28/2022]
Abstract
OBJECTIVE To determine if levetiracetam (LEV) enhances the impact in excitatory presynaptic terminals of a rate-limiting mechanism in vesicle trafficking termed supply rate depression that emerges to limit synaptic transmission during heavy, epileptiform use. METHODS The effect of LEV was measured with electrophysiologic assays of monosynaptic connections in ex vivo hippocampal slices from wild-type and synapsin knockout mice, and in primary cell culture neurons from wild-type and synaptic vesicle glycoprotein 2a (SV2a) knockout mice. RESULTS LEV enhanced the impact of supply rate depression at Schaffer collateral synapses by shortening the time course for induction. The LEV effect was selective for supply rate depression because other presynaptic vesicle trafficking mechanisms were not affected. The half maximal effective concentration (EC50 ) was ~50 μm. The maximal effect was ~15% and occurred at 100 μm, which is a clinically relevant concentration. An experimental protocol is established for distinguishing atypical antiepileptic drugs (AEDs) that affect supply rate depression, such as LEV, from typical AEDs, such as carbamazepine, that affect upstream mechanisms. The LEV effect was abolished at synapses from knockout mice lacking SV2a and from synapses lacking synapsin 1 and 2. SIGNIFICANCE The findings are consistent with the new hypothesis that LEV acts to treat epilepsy by accelerating the induction of supply rate depression at excitatory synapses during incipient epileptic activity. The absence of the effect in the knockouts confirms that presynaptic function is the target. More specifically, the absence in SV2a knockouts is consistent with previous binding studies suggesting that SV2a is the target for LEV. The absence in synapsin knockouts indicates that the phenotypic target intersects with the biochemical pathway that is altered in synapsin knockouts. The results from synapsin knockouts additionally suggest that development of functional analogs with increased potency might be possible because induction of supply rate depression is faster in synapsin knockouts compared to wild-type synapses treated with LEV.
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Deng PY, Klyachko VA. The diverse functions of short-term plasticity components in synaptic computations. Commun Integr Biol 2014. [DOI: 10.4161/cib.15870] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Wang Y, Gutfreund Y, Peña JL. Coding space-time stimulus dynamics in auditory brain maps. Front Physiol 2014; 5:135. [PMID: 24782781 PMCID: PMC3986518 DOI: 10.3389/fphys.2014.00135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Accepted: 03/19/2014] [Indexed: 11/21/2022] Open
Abstract
Sensory maps are often distorted representations of the environment, where ethologically-important ranges are magnified. The implication of a biased representation extends beyond increased acuity for having more neurons dedicated to a certain range. Because neurons are functionally interconnected, non-uniform representations influence the processing of high-order features that rely on comparison across areas of the map. Among these features are time-dependent changes of the auditory scene generated by moving objects. How sensory representation affects high order processing can be approached in the map of auditory space of the owl's midbrain, where locations in the front are over-represented. In this map, neurons are selective not only to location but also to location over time. The tuning to space over time leads to direction selectivity, which is also topographically organized. Across the population, neurons tuned to peripheral space are more selective to sounds moving into the front. The distribution of direction selectivity can be explained by spatial and temporal integration on the non-uniform map of space. Thus, the representation of space can induce biased computation of a second-order stimulus feature. This phenomenon is likely observed in other sensory maps and may be relevant for behavior.
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Affiliation(s)
- Yunyan Wang
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine Bronx, NY, USA
| | - Yoram Gutfreund
- The Rappaport Research Institute and Faculty of Medicine The Technion, Haifa, Israel
| | - José L Peña
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine Bronx, NY, USA
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Kramer F, Griesemer D, Bakker D, Brill S, Franke J, Frotscher E, Friauf E. Inhibitory glycinergic neurotransmission in the mammalian auditory brainstem upon prolonged stimulation: short-term plasticity and synaptic reliability. Front Neural Circuits 2014; 8:14. [PMID: 24653676 PMCID: PMC3948056 DOI: 10.3389/fncir.2014.00014] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Accepted: 02/13/2014] [Indexed: 11/13/2022] Open
Abstract
Short-term plasticity plays a key role in synaptic transmission and has been extensively investigated for excitatory synapses. Much less is known about inhibitory synapses. Here we analyze the performance of glycinergic connections between the medial nucleus of the trapezoid body (MNTB) and the lateral superior olive (LSO) in the auditory brainstem, where high spike rates as well as fast and precise neurotransmission are hallmarks. Analysis was performed in acute mouse slices shortly after hearing onset (postnatal day (P)11) and 8 days later (P19). Stimulation was done at 37°C with 1–400 Hz for 40 s. Moreover, in a novel approach named marathon experiments, a very prolonged stimulation protocol was employed, comprising 10 trials of 1-min challenge and 1-min recovery periods at 50 and 1 Hz, respectively, thus lasting up to 20 min and amounting to >30,000 stimulus pulses. IPSC peak amplitudes displayed short-term depression (STD) and synaptic attenuation in a frequency-dependent manner. No facilitation was observed. STD in the MNTB-LSO connections was less pronounced than reported in the upstream calyx of Held-MNTB connections. At P11, the STD level and the failure rate were slightly lower within the ms-to-s range than at P19. During prolonged stimulation periods lasting 40 s, P19 connections sustained virtually failure-free transmission up to frequencies of 100 Hz, whereas P11 connections did so only up to 50 Hz. In marathon experiments, P11 synapses recuperated reproducibly from synaptic attenuation during all recovery periods, demonstrating a robust synaptic machinery at hearing onset. At 26°C, transmission was severely impaired and comprised abnormally high amplitudes after minutes of silence, indicative of imprecisely regulated vesicle pools. Our study takes a fresh look at synaptic plasticity and stability by extending conventional stimulus periods in the ms-to-s range to minutes. It also provides a framework for future analyses of synaptic plasticity.
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Affiliation(s)
- Florian Kramer
- Animal Physiology Group, Department of Biology, University of Kaiserslautern Kaiserslautern, Germany
| | - Désirée Griesemer
- Animal Physiology Group, Department of Biology, University of Kaiserslautern Kaiserslautern, Germany
| | - Dennis Bakker
- Animal Physiology Group, Department of Biology, University of Kaiserslautern Kaiserslautern, Germany
| | - Sina Brill
- Animal Physiology Group, Department of Biology, University of Kaiserslautern Kaiserslautern, Germany
| | - Jürgen Franke
- Chair for Applied Mathematical Statistics, Department of Mathematics, University of Kaiserslautern Kaiserslautern, Germany ; Center for Mathematical and Computational Modeling, University of Kaiserslautern Kaiserslautern, Germany
| | - Erik Frotscher
- Animal Physiology Group, Department of Biology, University of Kaiserslautern Kaiserslautern, Germany
| | - Eckhard Friauf
- Animal Physiology Group, Department of Biology, University of Kaiserslautern Kaiserslautern, Germany ; Center for Mathematical and Computational Modeling, University of Kaiserslautern Kaiserslautern, Germany
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Analysis of Long-Term Depression in the Purkinje Cell Circuit (a Model Study). NEUROPHYSIOLOGY+ 2014. [DOI: 10.1007/s11062-014-9402-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Oline SN, Burger RM. Short-term synaptic depression is topographically distributed in the cochlear nucleus of the chicken. J Neurosci 2014; 34:1314-24. [PMID: 24453322 PMCID: PMC3898291 DOI: 10.1523/jneurosci.3073-13.2014] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Revised: 12/11/2013] [Accepted: 12/13/2013] [Indexed: 11/21/2022] Open
Abstract
In the auditory system, sounds are processed in parallel frequency-tuned circuits, beginning in the cochlea. Activity of auditory nerve fibers reflects this frequency-specific topographic pattern, known as tonotopy, and imparts frequency tuning onto their postsynaptic target neurons in the cochlear nucleus. In birds, cochlear nucleus magnocellularis (NM) neurons encode the temporal properties of acoustic stimuli by "locking" discharges to a particular phase of the input signal. Physiological specializations exist in gradients corresponding to the tonotopic axis in NM that reflect the characteristic frequency (CF) of their auditory nerve fiber inputs. One feature of NM neurons that has not been investigated across the tonotopic axis is short-term synaptic plasticity. NM offers a rather homogeneous population of neurons with a distinct topographical distribution of synaptic properties that is ideal for the investigation of specialized synaptic plasticity. Here we demonstrate for the first time that short-term synaptic depression (STD) is expressed topographically, where unitary high CF synapses are more robust with repeated stimulation. Correspondingly, high CF synapses drive spiking more reliably than their low CF counterparts. We show that postsynaptic AMPA receptor desensitization does not contribute to the observed difference in STD. Further, rate of recovery from depression, a presynaptic property, does not differ tonotopically. Rather, we show that another presynaptic feature, readily releasable pool (RRP) size, is tonotopically distributed and inversely correlated with vesicle release probability. Mathematical model results demonstrate that these properties of vesicle dynamics are sufficient to explain the observed tonotopic distribution of STD.
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Affiliation(s)
- Stefan N. Oline
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015
| | - R. Michael Burger
- Department of Biological Sciences, Lehigh University, Bethlehem, Pennsylvania 18015
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Ashida G, Funabiki K, Carr CE. Theoretical foundations of the sound analog membrane potential that underlies coincidence detection in the barn owl. Front Comput Neurosci 2013; 7:151. [PMID: 24265616 PMCID: PMC3821005 DOI: 10.3389/fncom.2013.00151] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2012] [Accepted: 10/11/2013] [Indexed: 11/15/2022] Open
Abstract
A wide variety of neurons encode temporal information via phase-locked spikes. In the avian auditory brainstem, neurons in the cochlear nucleus magnocellularis (NM) send phase-locked synaptic inputs to coincidence detector neurons in the nucleus laminaris (NL) that mediate sound localization. Previous modeling studies suggested that converging phase-locked synaptic inputs may give rise to a periodic oscillation in the membrane potential of their target neuron. Recent physiological recordings in vivo revealed that owl NL neurons changed their spike rates almost linearly with the amplitude of this oscillatory potential. The oscillatory potential was termed the sound analog potential, because of its resemblance to the waveform of the stimulus tone. The amplitude of the sound analog potential recorded in NL varied systematically with the interaural time difference (ITD), which is one of the most important cues for sound localization. In order to investigate the mechanisms underlying ITD computation in the NM-NL circuit, we provide detailed theoretical descriptions of how phase-locked inputs form oscillating membrane potentials. We derive analytical expressions that relate presynaptic, synaptic, and postsynaptic factors to the signal and noise components of the oscillation in both the synaptic conductance and the membrane potential. Numerical simulations demonstrate the validity of the theoretical formulations for the entire frequency ranges tested (1–8 kHz) and potential effects of higher harmonics on NL neurons with low best frequencies (<2 kHz).
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Affiliation(s)
- Go Ashida
- Department of Biology, University of Maryland College Park, MD, USA
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Bui L, Glavinović MI. Is replenishment of the readily releasable pool associated with vesicular movement? Cogn Neurodyn 2013; 8:99-110. [PMID: 24624230 DOI: 10.1007/s11571-013-9264-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 06/19/2013] [Accepted: 07/23/2013] [Indexed: 12/30/2022] Open
Abstract
At the excitatory synapse of rat hippocampus the short-term synaptic depression observed during long high-frequency stimulation is associated with slower replenishment of the readily-releasable pool. Given that the replenishment rate is also not [Ca(++)]o sensitive this puts into question a widely held notion that the vesicles-constrained by the cytoskeleton and rendered free from such constraints by Ca(++) entry that renders them more mobile-are important in the replenishment of the readily-releasable pool. This raises a question-Is vesicular replenishment of the readily releasable pool associated with significant movement? To answer this question we evaluated how okadaic acid and staurosporine (compounds known to affect vesicular mobility) influence the replenishment rate. We used patterned stimulation on the Schaffer collateral fiber pathway and recorded the excitatory post-synaptic currents (EPSCs) from rat CA1 neurons, in the absence and presence of these drugs. The parameters of a circuit model with two vesicular pools were estimated by minimizing the squared difference between the ESPC amplitudes and simulated model output. [Ca(2+)]o did not influence the progressive decrease of the replenishment rate during long, high frequency stimulation. Okadaic acid did not significantly affect any parameters of the vesicular storage and release system, including the replenishment rate. Staurosporine reduced the replenishment coupling, but not the replenishment rate, and this is owing to the fact that it also reduces the ability of the readily releasable pool to contain quanta. Moreover, these compounds were ineffective in influencing how the replenishment rate decreases during long, high frequency stimulation. In conclusion at the excitatory synapses of rat hippocampus the replenishment of the readily releasable pool does not appear to be associated with a significant vesicular movement, and during long high frequency stimulation [Ca(++)]o does not influence the progressive decrease of vesicular replenishment.
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Affiliation(s)
- Loc Bui
- Department of Physiology, McGill University, 3655 Sir William Osler Promenade, Montreal, H3G 1Y6 Canada
| | - Mladen I Glavinović
- Department of Physiology, McGill University, 3655 Sir William Osler Promenade, Montreal, H3G 1Y6 Canada
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Dynamic Control of Synaptic Vesicle Replenishment and Short-Term Plasticity by Ca2+-Calmodulin-Munc13-1 Signaling. Neuron 2013; 79:82-96. [DOI: 10.1016/j.neuron.2013.05.011] [Citation(s) in RCA: 120] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/13/2013] [Indexed: 02/02/2023]
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Reich S, Rosenbaum R. The impact of short term synaptic depression and stochastic vesicle dynamics on neuronal variability. J Comput Neurosci 2013; 35:39-53. [PMID: 23354693 DOI: 10.1007/s10827-012-0438-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 12/17/2012] [Accepted: 12/26/2012] [Indexed: 11/26/2022]
Abstract
Neuronal variability plays a central role in neural coding and impacts the dynamics of neuronal networks. Unreliability of synaptic transmission is a major source of neural variability: synaptic neurotransmitter vesicles are released probabilistically in response to presynaptic action potentials and are recovered stochastically in time. The dynamics of this process of vesicle release and recovery interacts with variability in the arrival times of presynaptic spikes to shape the variability of the postsynaptic response. We use continuous time Markov chain methods to analyze a model of short term synaptic depression with stochastic vesicle dynamics coupled with three different models of presynaptic spiking: one model in which the timing of presynaptic action potentials are modeled as a Poisson process, one in which action potentials occur more regularly than a Poisson process (sub-Poisson) and one in which action potentials occur more irregularly (super-Poisson). We use this analysis to investigate how variability in a presynaptic spike train is transformed by short term depression and stochastic vesicle dynamics to determine the variability of the postsynaptic response. We find that sub-Poisson presynaptic spiking increases the average rate at which vesicles are released, that the number of vesicles released over a time window is more variable for smaller time windows than larger time windows and that fast presynaptic spiking gives rise to Poisson-like variability of the postsynaptic response even when presynaptic spike times are non-Poisson. Our results complement and extend previously reported theoretical results and provide possible explanations for some trends observed in recorded data.
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Affiliation(s)
- Steven Reich
- Department of Mathematics, University of Pittsburgh, Pittsburgh, PA, USA
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Higgs MH, Kuznetsova MS, Spain WJ. Adaptation of spike timing precision controls the sensitivity to interaural time difference in the avian auditory brainstem. J Neurosci 2012; 32:15489-94. [PMID: 23115186 PMCID: PMC3518488 DOI: 10.1523/jneurosci.1865-12.2012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 08/31/2012] [Accepted: 09/07/2012] [Indexed: 01/01/2023] Open
Abstract
While adaptation is widely thought to facilitate neural coding, the form of adaptation should depend on how the signals are encoded. Monaural neurons early in the interaural time difference (ITD) pathway encode the phase of sound input using spike timing rather than firing rate. Such neurons in chicken nucleus magnocellularis (NM) adapt to ongoing stimuli by increasing firing rate and decreasing spike timing precision. We measured NM neuron responses while adapting them to simulated physiological input, and used these responses to construct inputs to binaural coincidence detector neurons in nucleus laminaris (NL). Adaptation of spike timing in NM reduced ITD sensitivity in NL, demonstrating the dominant role of timing in the short-term plasticity as well as the immediate response of this sound localization circuit.
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Affiliation(s)
- Matthew H. Higgs
- Neurology Section, Department of Veterans Affairs Medical Center, Seattle, Washington 98108, and
- Department of Physiology and Biophysics
| | - Marina S. Kuznetsova
- Department of Physiology and Biophysics
- Interdisciplinary Graduate Program in Neurobiology and Behavior, and
| | - William J. Spain
- Neurology Section, Department of Veterans Affairs Medical Center, Seattle, Washington 98108, and
- Department of Physiology and Biophysics
- Department of Neurology, University of Washington, Seattle, Washington 98195
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Rosenbaum R, Rubin JE, Doiron B. Short-term synaptic depression and stochastic vesicle dynamics reduce and shape neuronal correlations. J Neurophysiol 2012; 109:475-84. [PMID: 23114215 DOI: 10.1152/jn.00733.2012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Correlated neuronal activity is an important feature in many neural codes, a neural correlate of a variety of cognitive states, as well as a signature of several disease states in the nervous system. The cellular and circuit mechanics of neural correlations is a vibrant area of research. Synapses throughout the cortex exhibit a form of short-term depression where increased presynaptic firing rates deplete neurotransmitter vesicles, which transiently reduces synaptic efficacy. The release and recovery of these vesicles are inherently stochastic, and this stochasticity introduces variability into the conductance elicited by depressing synapses. The impact of spiking and subthreshold membrane dynamics on the transfer of neuronal correlations has been studied intensively, but an investigation of the impact of short-term synaptic depression and stochastic vesicle dynamics on correlation transfer is lacking. We find that short-term synaptic depression and stochastic vesicle dynamics can substantially reduce correlations, shape the timescale over which these correlations occur, and alter the dependence of spiking correlations on firing rate. Our results show that short-term depression and stochastic vesicle dynamics need to be taken into account when modeling correlations in neuronal populations.
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Affiliation(s)
- Robert Rosenbaum
- Department of Mathematics, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
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