201
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Labarrera C, Deitcher Y, Dudai A, Weiner B, Kaduri Amichai A, Zylbermann N, London M. Adrenergic Modulation Regulates the Dendritic Excitability of Layer 5 Pyramidal Neurons In Vivo. Cell Rep 2019; 23:1034-1044. [PMID: 29694883 DOI: 10.1016/j.celrep.2018.03.103] [Citation(s) in RCA: 48] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2017] [Revised: 01/22/2018] [Accepted: 03/19/2018] [Indexed: 02/01/2023] Open
Abstract
The excitability of the apical tuft of layer 5 pyramidal neurons is thought to play a crucial role in behavioral performance and synaptic plasticity. We show that the excitability of the apical tuft is sensitive to adrenergic neuromodulation. Using two-photon dendritic Ca2+ imaging and in vivo whole-cell and extracellular recordings in awake mice, we show that application of the α2A-adrenoceptor agonist guanfacine increases the probability of dendritic Ca2+ events in the tuft and lowers the threshold for dendritic Ca2+ spikes. We further show that these effects are likely to be mediated by the dendritic current Ih. Modulation of Ih in a realistic compartmental model controlled both the generation and magnitude of dendritic calcium spikes in the apical tuft. These findings suggest that adrenergic neuromodulation may affect cognitive processes such as sensory integration, attention, and working memory by regulating the sensitivity of layer 5 pyramidal neurons to top-down inputs.
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Affiliation(s)
- Christina Labarrera
- Edmond and Lily Safra Center for Brain Sciences and Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Yair Deitcher
- Edmond and Lily Safra Center for Brain Sciences and Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Amir Dudai
- Edmond and Lily Safra Center for Brain Sciences and Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Benjamin Weiner
- Edmond and Lily Safra Center for Brain Sciences and Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Adi Kaduri Amichai
- Edmond and Lily Safra Center for Brain Sciences and Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Neta Zylbermann
- Edmond and Lily Safra Center for Brain Sciences and Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Michael London
- Edmond and Lily Safra Center for Brain Sciences and Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
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202
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Leyrer‐Jackson JM, Thomas MP. Dopaminergic D1 receptor effects on commissural inputs targeting layer V pyramidal subtypes of the mouse medial prefrontal cortex. Physiol Rep 2019; 7:e14256. [PMID: 31650716 PMCID: PMC6813257 DOI: 10.14814/phy2.14256] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Revised: 09/09/2019] [Accepted: 09/10/2019] [Indexed: 11/28/2022] Open
Abstract
In humans, prefrontal cortical areas are known to support goal-directed behaviors, mediating a variety of functions that render behavior more flexible in the face of changing environmental demands. In mice, these functions are mediated by homologous regions within medial prefrontal cortex (mPFC) and rely heavily on proper dopaminergic tone. Comprised of two major subtypes, pyramidal tract (PT) and intratelencephalic (IT), layer V pyramidal cells serve as the major outputs of the mPFC, targeting brainstem nuclei and the contralateral hemisphere, respectively. However, it remains relatively unknown how cortical inputs targeting these subtypes are integrated. We explored how layer V pyramidal cell subtypes integrate commissural inputs, which integrate information flow between the hemispheres. An optogenetic approach was used to elicit commissural fiber activation onto PT and IT cells and the effects of D1 receptor activation on elicited EPSPs were explored. We showed that commissural inputs into PT and IT cells elicit facilitating and depressing EPSP patterns, respectively. D1 receptor activation increased the initial EPSP amplitude, enhanced EPSP facilitation, and prolonged EPSP decay time constant in PT cells. In IT cells, D1 receptor activation increased commissural-evoked initial EPSP amplitude but did not affect facilitation or EPSP shape. Furthermore, D1 receptor activation elicited burst firing in a subset of PT cells in response to commissural fiber activation. Combined, these results lend insight into the role of dopamine in promoting persistent firing and temporal integration in PT and IT cells, respectively, that in turn may contribute to working memory functions.
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Affiliation(s)
- Jonna M. Leyrer‐Jackson
- School of PsychologyPsychology Department – Behavioral NeuroscienceArizona State UniversityTempeArizona
| | - Mark P. Thomas
- School of Biological SciencesUniversity of Northern ColoradoGreeleyColorado
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203
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Todo Y, Tang Z, Todo H, Ji J, Yamashita K. Neurons with Multiplicative Interactions of Nonlinear Synapses. Int J Neural Syst 2019; 29:1950012. [DOI: 10.1142/s0129065719500126] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Neurons are the fundamental units of the brain and nervous system. Developing a good modeling of human neurons is very important not only to neurobiology but also to computer science and many other fields. The McCulloch and Pitts neuron model is the most widely used neuron model, but has long been criticized as being oversimplified in view of properties of real neuron and the computations they perform. On the other hand, it has become widely accepted that dendrites play a key role in the overall computation performed by a neuron. However, the modeling of the dendritic computations and the assignment of the right synapses to the right dendrite remain open problems in the field. Here, we propose a novel dendritic neural model (DNM) that mimics the essence of known nonlinear interaction among inputs to the dendrites. In the model, each input is connected to branches through a distance-dependent nonlinear synapse, and each branch performs a simple multiplication on the inputs. The soma then sums the weighted products from all branches and produces the neuron’s output signal. We show that the rich nonlinear dendritic response and the powerful nonlinear neural computational capability, as well as many known neurobiological phenomena of neurons and dendrites, may be understood and explained by the DNM. Furthermore, we show that the model is capable of learning and developing an internal structure, such as the location of synapses in the dendritic branch and the type of synapses, that is appropriate for a particular task — for example, the linearly nonseparable problem, a real-world benchmark problem — Glass classification and the directional selectivity problem.
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Affiliation(s)
- Yuki Todo
- Faculty of Electrical and Computer Engineering, Kanazawa University, Kakuma-Machi, Kanazawa 920-1192, Japan
| | - Zheng Tang
- Department of Intelligence Information Systems, University of Toyama, 3190, Gofuku, Toyama 930-8555, Japan
| | - Hiroyoshi Todo
- Department of Pharmaceutical Technology, University of Toyama, 2630, Sugitani, Toyama 930-0194, Japan
| | - Junkai Ji
- Department of Intelligence Information Systems, University of Toyama, 3190, Gofuku, Toyama 930-8555, Japan
| | - Kazuya Yamashita
- Information Technology Center, University of Toyama, 3190, Gofuku, Toyama 930-8555, Japan
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204
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Abstract
Axons functionally link the somato-dendritic compartment to synaptic terminals. Structurally and functionally diverse, they accomplish a central role in determining the delays and reliability with which neuronal ensembles communicate. By combining their active and passive biophysical properties, they ensure a plethora of physiological computations. In this review, we revisit the biophysics of generation and propagation of electrical signals in the axon and their dynamics. We further place the computational abilities of axons in the context of intracellular and intercellular coupling. We discuss how, by means of sophisticated biophysical mechanisms, axons expand the repertoire of axonal computation, and thereby, of neural computation.
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Affiliation(s)
- Pepe Alcami
- Division of Neurobiology, Department of Biology II, Ludwig-Maximilians-Universitaet Muenchen, Martinsried, Germany
- Department of Behavioural Neurobiology, Max Planck Institute for Ornithology, Seewiesen, Germany
| | - Ahmed El Hady
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ, United States
- Howard Hughes Medical Institute, Princeton University, Princeton, NJ, United States
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205
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Aru J, Suzuki M, Rutiku R, Larkum ME, Bachmann T. Coupling the State and Contents of Consciousness. Front Syst Neurosci 2019; 13:43. [PMID: 31543762 PMCID: PMC6729974 DOI: 10.3389/fnsys.2019.00043] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 08/13/2019] [Indexed: 11/13/2022] Open
Abstract
One fundamental feature of consciousness is that the contents of consciousness depend on the state of consciousness. Here, we propose an answer to why this is so: both the state and the contents of consciousness depend on the activity of cortical layer 5 pyramidal (L5p) neurons. These neurons affect both cortical and thalamic processing, hence coupling the cortico-cortical and thalamo-cortical loops with each other. Functionally this coupling corresponds to the coupling between the state and the contents of consciousness. Together the cortico-cortical and thalamo-cortical loops form a thalamo-cortical broadcasting system, where the L5p cells are the central elements. This perspective makes one quite specific prediction: cortical processing that does not include L5p neurons will be unconscious. More generally, the present perspective suggests that L5p neurons have a central role in the mechanisms underlying consciousness.
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Affiliation(s)
- Jaan Aru
- Institute of Biology, Humboldt University of Berlin, Berlin, Germany
- Institute of Computer Science, University of Tartu, Tartu, Estonia
- School of Law, University of Tartu, Tartu, Estonia
| | - Mototaka Suzuki
- Neurocure Center for Excellence, Charité Universitätsmedizin Berlin, Berlin, Germany
| | | | - Matthew E. Larkum
- Institute of Biology, Humboldt University of Berlin, Berlin, Germany
- Neurocure Center for Excellence, Charité Universitätsmedizin Berlin, Berlin, Germany
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206
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Payeur A, Béïque JC, Naud R. Classes of dendritic information processing. Curr Opin Neurobiol 2019; 58:78-85. [PMID: 31419712 DOI: 10.1016/j.conb.2019.07.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 07/14/2019] [Indexed: 11/19/2022]
Abstract
Dendrites are much more than passive neuronal components. Mounting experimental evidence and decades of computational work have decisively shown that dendrites leverage a host of nonlinear biophysical phenomena and actively participate in sophisticated computations, at the level of the single neuron and at the level of the network. However, a coherent view of their processing power is still lacking and dendrites are largely neglected in neural network models. Here, we describe four classes of dendritic information processing and delineate their implications at the algorithmic level. We propose that beyond the well-known spatiotemporal filtering of their inputs, dendrites are capable of selecting, routing and multiplexing information. By separating dendritic processing from axonal outputs, neuron networks gain a degree of freedom with implications for perception and learning.
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Affiliation(s)
- Alexandre Payeur
- Ottawa Brain and Mind Institute, Centre for Neural Dynamics, Department of Cellular and Molecular Neuroscience, University of Ottawa, Canada
| | - Jean-Claude Béïque
- Ottawa Brain and Mind Institute, Centre for Neural Dynamics, Department of Cellular and Molecular Neuroscience, University of Ottawa, Canada
| | - Richard Naud
- Ottawa Brain and Mind Institute, Centre for Neural Dynamics, Department of Cellular and Molecular Neuroscience, University of Ottawa, Canada; Department of Physics, University of Ottawa, 150 Louis Pasteur Pet, Ottawa, ON, K1N 6N5, Canada.
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207
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Ujfalussy BB, Makara JK, Lengyel M, Branco T. Global and Multiplexed Dendritic Computations under In Vivo-like Conditions. Neuron 2019; 100:579-592.e5. [PMID: 30408443 PMCID: PMC6226578 DOI: 10.1016/j.neuron.2018.08.032] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 07/07/2018] [Accepted: 08/21/2018] [Indexed: 10/27/2022]
Abstract
Dendrites integrate inputs nonlinearly, but it is unclear how these nonlinearities contribute to the overall input-output transformation of single neurons. We developed statistically principled methods using a hierarchical cascade of linear-nonlinear subunits (hLN) to model the dynamically evolving somatic response of neurons receiving complex, in vivo-like spatiotemporal synaptic input patterns. We used the hLN to predict the somatic membrane potential of an in vivo-validated detailed biophysical model of a L2/3 pyramidal cell. Linear input integration with a single global dendritic nonlinearity achieved above 90% prediction accuracy. A novel hLN motif, input multiplexing into parallel processing channels, could improve predictions as much as conventionally used additional layers of local nonlinearities. We obtained similar results in two other cell types. This approach provides a data-driven characterization of a key component of cortical circuit computations: the input-output transformation of neurons during in vivo-like conditions.
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Affiliation(s)
- Balázs B Ujfalussy
- MRC Laboratory of Molecular Biology, Cambridge, UK; Laboratory of Neuronal Signaling, Institute of Experimental Medicine, Budapest, Hungary; Computational and Biological Learning Lab, Department of Engineering, University of Cambridge, Cambridge, UK; MTA Wigner Research Center for Physics, Budapest, Hungary.
| | - Judit K Makara
- Laboratory of Neuronal Signaling, Institute of Experimental Medicine, Budapest, Hungary
| | - Máté Lengyel
- Computational and Biological Learning Lab, Department of Engineering, University of Cambridge, Cambridge, UK; Department of Cognitive Science, Central European University, Budapest, Hungary
| | - Tiago Branco
- MRC Laboratory of Molecular Biology, Cambridge, UK; Sainsbury Wellcome Centre, University College London, London, UK
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208
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Abstract
Tactile sensory information from facial whiskers provides nocturnal tunnel-dwelling rodents, including mice and rats, with important spatial and textural information about their immediate surroundings. Whiskers are moved back and forth to scan the environment (whisking), and touch signals from each whisker evoke sparse patterns of neuronal activity in whisker-related primary somatosensory cortex (wS1; barrel cortex). Whisking is accompanied by desynchronized brain states and cell-type-specific changes in spontaneous and evoked neuronal activity. Tactile information, including object texture and location, appears to be computed in wS1 through integration of motor and sensory signals. wS1 also directly controls whisker movements and contributes to learned, whisker-dependent, goal-directed behaviours. The cell-type-specific neuronal circuitry in wS1 that contributes to whisker sensory perception is beginning to be defined.
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209
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The Autism-Associated Gene Scn2a Contributes to Dendritic Excitability and Synaptic Function in the Prefrontal Cortex. Neuron 2019; 103:673-685.e5. [PMID: 31230762 DOI: 10.1016/j.neuron.2019.05.037] [Citation(s) in RCA: 116] [Impact Index Per Article: 23.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 03/23/2019] [Accepted: 05/22/2019] [Indexed: 12/20/2022]
Abstract
Autism spectrum disorder (ASD) is strongly associated with de novo gene mutations. One of the most commonly affected genes is SCN2A. ASD-associated SCN2A mutations impair the encoded protein NaV1.2, a sodium channel important for action potential initiation and propagation in developing excitatory cortical neurons. The link between an axonal sodium channel and ASD, a disorder typically attributed to synaptic or transcriptional dysfunction, is unclear. Here we show that NaV1.2 is unexpectedly critical for dendritic excitability and synaptic function in mature pyramidal neurons in addition to regulating early developmental axonal excitability. NaV1.2 loss reduced action potential backpropagation into dendrites, impairing synaptic plasticity and synaptic strength, even when NaV1.2 expression was disrupted in a cell-autonomous fashion late in development. These results reveal a novel dendritic function for NaV1.2, providing insight into cellular mechanisms probably underlying circuit and behavioral dysfunction in ASD.
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210
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Shin W, Kweon H, Kang R, Kim D, Kim K, Kang M, Kim SY, Hwang SN, Kim JY, Yang E, Kim H, Kim E. Scn2a Haploinsufficiency in Mice Suppresses Hippocampal Neuronal Excitability, Excitatory Synaptic Drive, and Long-Term Potentiation, and Spatial Learning and Memory. Front Mol Neurosci 2019; 12:145. [PMID: 31249508 PMCID: PMC6582764 DOI: 10.3389/fnmol.2019.00145] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 05/17/2019] [Indexed: 01/13/2023] Open
Abstract
Nav1.2, a voltage-gated sodium channel subunit encoded by the Scn2a gene, has been implicated in various brain disorders, including epilepsy, autism spectrum disorder, intellectual disability, and schizophrenia. Nav1.2 is known to regulate the generation of action potentials in the axon initial segment and their propagation along axonal pathways. Nav1.2 also regulates synaptic integration and plasticity by promoting back-propagation of action potentials to dendrites, but whether Nav1.2 deletion in mice affects neuronal excitability, synaptic transmission, synaptic plasticity, and/or disease-related animal behaviors remains largely unclear. Here, we report that mice heterozygous for the Scn2a gene (Scn2a+/- mice) show decreased neuronal excitability and suppressed excitatory synaptic transmission in the presence of network activity in the hippocampus. In addition, Scn2a+/- mice show suppressed hippocampal long-term potentiation (LTP) in association with impaired spatial learning and memory, but show largely normal locomotor activity, anxiety-like behavior, social interaction, repetitive behavior, and whole-brain excitation. These results suggest that Nav1.2 regulates hippocampal neuronal excitability, excitatory synaptic drive, LTP, and spatial learning and memory in mice.
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Affiliation(s)
- Wangyong Shin
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Hanseul Kweon
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Ryeonghwa Kang
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Doyoun Kim
- Center for Synaptic Brain Dysfunctions, Institute for Basic Science, Daejeon, South Korea
| | - Kyungdeok Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Muwon Kang
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Seo Yeong Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea
| | - Sun Nam Hwang
- Center for Synaptic Brain Dysfunctions, Institute for Basic Science, Daejeon, South Korea
| | - Jin Yong Kim
- Department of Anatomy and Division of Brain Korea 21, Biomedical Science, College of Medicine, Korea University, Seoul, South Korea
| | - Esther Yang
- Department of Anatomy and Division of Brain Korea 21, Biomedical Science, College of Medicine, Korea University, Seoul, South Korea
| | - Hyun Kim
- Department of Anatomy and Division of Brain Korea 21, Biomedical Science, College of Medicine, Korea University, Seoul, South Korea
| | - Eunjoon Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea.,Center for Synaptic Brain Dysfunctions, Institute for Basic Science, Daejeon, South Korea
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211
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Deneux T, Harrell ER, Kempf A, Ceballo S, Filipchuk A, Bathellier B. Context-dependent signaling of coincident auditory and visual events in primary visual cortex. eLife 2019; 8:44006. [PMID: 31115334 PMCID: PMC6544434 DOI: 10.7554/elife.44006] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 05/20/2019] [Indexed: 01/10/2023] Open
Abstract
Detecting rapid, coincident changes across sensory modalities is essential for recognition of sudden threats or events. Using two-photon calcium imaging in identified cell types in awake, head-fixed mice, we show that, among the basic features of a sound envelope, loud sound onsets are a dominant feature coded by the auditory cortex neurons projecting to primary visual cortex (V1). In V1, a small number of layer 1 interneurons gates this cross-modal information flow in a context-dependent manner. In dark conditions, auditory cortex inputs lead to suppression of the V1 population. However, when sound input coincides with a visual stimulus, visual responses are boosted in V1, most strongly after loud sound onsets. Thus, a dynamic, asymmetric circuit connecting AC and V1 contributes to the encoding of visual events that are coincident with sounds.
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Affiliation(s)
- Thomas Deneux
- Department for Integrative and Computational Neuroscience (ICN), Paris-Saclay Institute of Neuroscience (NeuroPSI), UMR9197 CNRS, University Paris Sud, Gif-sur-Yvette, France
| | - Evan R Harrell
- Department for Integrative and Computational Neuroscience (ICN), Paris-Saclay Institute of Neuroscience (NeuroPSI), UMR9197 CNRS, University Paris Sud, Gif-sur-Yvette, France
| | - Alexandre Kempf
- Department for Integrative and Computational Neuroscience (ICN), Paris-Saclay Institute of Neuroscience (NeuroPSI), UMR9197 CNRS, University Paris Sud, Gif-sur-Yvette, France
| | - Sebastian Ceballo
- Department for Integrative and Computational Neuroscience (ICN), Paris-Saclay Institute of Neuroscience (NeuroPSI), UMR9197 CNRS, University Paris Sud, Gif-sur-Yvette, France
| | - Anton Filipchuk
- Department for Integrative and Computational Neuroscience (ICN), Paris-Saclay Institute of Neuroscience (NeuroPSI), UMR9197 CNRS, University Paris Sud, Gif-sur-Yvette, France
| | - Brice Bathellier
- Department for Integrative and Computational Neuroscience (ICN), Paris-Saclay Institute of Neuroscience (NeuroPSI), UMR9197 CNRS, University Paris Sud, Gif-sur-Yvette, France
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212
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Burke KJ, Bender KJ. Modulation of Ion Channels in the Axon: Mechanisms and Function. Front Cell Neurosci 2019; 13:221. [PMID: 31156397 PMCID: PMC6533529 DOI: 10.3389/fncel.2019.00221] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Accepted: 05/01/2019] [Indexed: 12/11/2022] Open
Abstract
The axon is responsible for integrating synaptic signals, generating action potentials (APs), propagating those APs to downstream synapses and converting them into patterns of neurotransmitter vesicle release. This process is mediated by a rich assortment of voltage-gated ion channels whose function can be affected on short and long time scales by activity. Moreover, neuromodulators control the activity of these proteins through G-protein coupled receptor signaling cascades. Here, we review cellular mechanisms and signaling pathways involved in axonal ion channel modulation and examine how changes to ion channel function affect AP initiation, AP propagation, and the release of neurotransmitter. We then examine how these mechanisms could modulate synaptic function by focusing on three key features of synaptic information transmission: synaptic strength, synaptic variability, and short-term plasticity. Viewing these cellular mechanisms of neuromodulation from a functional perspective may assist in extending these findings to theories of neural circuit function and its neuromodulation.
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Affiliation(s)
| | - Kevin J. Bender
- Neuroscience Graduate Program and Department of Neurology, Kavli Institute for Fundamental Neuroscience, Weill Institute for Neurosciences, University of California, San Francisco, San Francisco, CA, United States
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213
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Hertäg L, Sprekeler H. Amplifying the redistribution of somato-dendritic inhibition by the interplay of three interneuron types. PLoS Comput Biol 2019; 15:e1006999. [PMID: 31095556 PMCID: PMC6541306 DOI: 10.1371/journal.pcbi.1006999] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 05/29/2019] [Accepted: 04/01/2019] [Indexed: 01/24/2023] Open
Abstract
GABAergic interneurons play an important role in shaping the activity of excitatory pyramidal cells (PCs). How the various inhibitory cell types contribute to neuronal information processing, however, is not resolved. Here, we propose a functional role for a widespread network motif consisting of parvalbumin- (PV), somatostatin- (SOM) and vasoactive intestinal peptide (VIP)-expressing interneurons. Following the idea that PV and SOM interneurons control the distribution of somatic and dendritic inhibition onto PCs, we suggest that mutual inhibition between VIP and SOM cells translates weak inputs to VIP interneurons into large changes of somato-dendritic inhibition of PCs. Using a computational model, we show that the neuronal and synaptic properties of the circuit support this hypothesis. Moreover, we demonstrate that the SOM-VIP motif allows transient inputs to persistently switch the circuit between two processing modes, in which top-down inputs onto apical dendrites of PCs are either integrated or cancelled. Neurons in the brain can be classified as excitatory or inhibitory based on whether they activate or deactivate the cells to whom they send signals. Compared to their excitatory counterpart, inhibitory neurons present themselves as a wild diversity of cell classes. It is broadly believed that these classes serve different purposes, but as of now, those are poorly understood. In this article, we suggest how an intricate interplay of three inhibitory cell classes can control whether internal signals—such as predictions, memory signals or motor commands—are taken into account when sensory signals are interpreted. Using a mathematical model and computer simulations, we show that such internal signals can be shut down by regulating which inhibitory cell types are active, and that the interaction of different cell classes allows weak control signals to do so.
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Affiliation(s)
- Loreen Hertäg
- Modelling of Cognitive Processes, Berlin Institute of Technology, Berlin, Germany.,Bernstein Center for Computational Neuroscience, Berlin, Germany
| | - Henning Sprekeler
- Modelling of Cognitive Processes, Berlin Institute of Technology, Berlin, Germany.,Bernstein Center for Computational Neuroscience, Berlin, Germany
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214
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Wu X, Mel GC, Strouse DJ, Mel BW. How Dendrites Affect Online Recognition Memory. PLoS Comput Biol 2019; 15:e1006892. [PMID: 31050662 PMCID: PMC6527246 DOI: 10.1371/journal.pcbi.1006892] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 05/20/2019] [Accepted: 02/18/2019] [Indexed: 11/18/2022] Open
Abstract
In order to record the stream of autobiographical information that defines our unique personal history, our brains must form durable memories from single brief exposures to the patterned stimuli that impinge on them continuously throughout life. However, little is known about the computational strategies or neural mechanisms that underlie the brain's ability to perform this type of "online" learning. Based on increasing evidence that dendrites act as both signaling and learning units in the brain, we developed an analytical model that relates online recognition memory capacity to roughly a dozen dendritic, network, pattern, and task-related parameters. We used the model to determine what dendrite size maximizes storage capacity under varying assumptions about pattern density and noise level. We show that over a several-fold range of both of these parameters, and over multiple orders-of-magnitude of memory size, capacity is maximized when dendrites contain a few hundred synapses-roughly the natural number found in memory-related areas of the brain. Thus, in comparison to entire neurons, dendrites increase storage capacity by providing a larger number of better-sized learning units. Our model provides the first normative theory that explains how dendrites increase the brain's capacity for online learning; predicts which combinations of parameter settings we should expect to find in the brain under normal operating conditions; leads to novel interpretations of an array of existing experimental results; and provides a tool for understanding which changes associated with neurological disorders, aging, or stress are most likely to produce memory deficits-knowledge that could eventually help in the design of improved clinical treatments for memory loss.
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Affiliation(s)
- Xundong Wu
- School of Computer Science and Technology, Hangzhou Dianzi University, Hangzhou, China
| | - Gabriel C. Mel
- Computer Science Department, University of Southern California, Los Angeles, CA, United States
| | - D. J. Strouse
- Physics Department, Princeton University, Princeton, NJ, United States
| | - Bartlett W. Mel
- Biomedical Engineering Department and Neuroscience Graduate Program, University of Southern California, Los Angeles, CA, United States
- * E-mail:
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215
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Diverse synaptic and dendritic mechanisms of complex spike burst generation in hippocampal CA3 pyramidal cells. Nat Commun 2019; 10:1859. [PMID: 31015414 PMCID: PMC6478939 DOI: 10.1038/s41467-019-09767-w] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 03/27/2019] [Indexed: 01/21/2023] Open
Abstract
Complex spike bursts (CSBs) represent a characteristic firing pattern of hippocampal pyramidal cells (PCs). In CA1PCs, CSBs are driven by regenerative dendritic plateau potentials, produced by correlated entorhinal cortical and CA3 inputs that simultaneously depolarize distal and proximal dendritic domains. However, in CA3PCs neither the generation mechanisms nor the computational role of CSBs are well elucidated. We show that CSBs are induced by dendritic Ca2+ spikes in CA3PCs. Surprisingly, the ability of CA3PCs to produce CSBs is heterogeneous, with non-uniform synaptic input-output transformation rules triggering CSBs. The heterogeneity is partly related to the topographic position of CA3PCs; we identify two ion channel types, HCN and Kv2 channels, whose proximodistal activity gradients contribute to subregion-specific modulation of CSB propensity. Our results suggest that heterogeneous dendritic integrative properties, along with previously reported synaptic connectivity gradients, define functional subpopulations of CA3PCs that may support CA3 network computations underlying associative memory processes.
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216
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Zhou JF, Yuan WJ, Chen D, Wang BH, Zhou Z, Boccaletti S, Wang Z. Synaptic modifications driven by spike-timing-dependent plasticity in weakly coupled bursting neurons. Phys Rev E 2019; 99:032419. [PMID: 30999534 DOI: 10.1103/physreve.99.032419] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Indexed: 12/25/2022]
Abstract
In the course of development, sleep, or mental disorders, certain neurons in the brain display spontaneous spike-burst activity. The synaptic plasticity evoked by such activity is here studied in the presence of spike-timing-dependent plasticity (STDP). In two chemically coupled bursting model neurons, the spike-burst activity can translate the STDP related to pre- and postsynaptic spike activity into burst-timing-dependent plasticity (BTDP), based on the timing of bursts of pre- and postsynaptic neurons. The resulting BTDP exhibits exponential decays with the same time scales as those of STDP. In weakly coupled bursting neuron networks, the synaptic modification driven by the spike-burst activity obeys a power-law distribution. The model can also produce a power-law distribution of synaptic weights. Here, the considered bursting behavior is made of stereotypical groups of spikes, and bursting is evenly spaced by long intervals.
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Affiliation(s)
- Jian-Fang Zhou
- College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000, China
| | - Wu-Jie Yuan
- College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000, China
| | - Debao Chen
- College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000, China
| | - Bing-Hong Wang
- Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
| | - Zhao Zhou
- College of Physics and Electronic Information, Huaibei Normal University, Huaibei 235000, China
| | - Stefano Boccaletti
- CNR-Institute of Complex Systems, Via Madonna del Piano, 10, 50019 Sesto Fiorentino, Florence, Italy.,Unmanned Systems Research Institute, Northwestern Polytechnical University, Xi'an, 710072 Shanxi, China
| | - Zhen Wang
- Center for OPTical IMagery Analysis and Learning (OPTIMAL), Northwestern Polytechnical University, Xi'an, 710072 Shanxi, China
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217
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Parrish RR, Codadu NK, Mackenzie-Gray Scott C, Trevelyan AJ. Feedforward inhibition ahead of ictal wavefronts is provided by both parvalbumin- and somatostatin-expressing interneurons. J Physiol 2019; 597:2297-2314. [PMID: 30784081 PMCID: PMC6462485 DOI: 10.1113/jp277749] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Accepted: 02/19/2019] [Indexed: 12/29/2022] Open
Abstract
Key points There is a rapid interneuronal response to focal activity in cortex, which restrains laterally propagating activity, including spreading epileptiform activity. The interneuronal response involves intense activation of both parvalbumin‐ and somatostatin‐expressing interneurons. Interneuronal bursting is time‐locked to glutamatergic barrages in the pre‐ictal period. Ca2+ imaging using conditional expression of GCaMP6f provides an accurate readout of the evolving firing patterns in both types of interneuron. The activation profiles of the two interneuronal classes are temporally offset, with the parvalbumin population being activated first, and typically, at higher rates.
Abstract Previous work has described powerful restraints on laterally spreading activity in cortical networks, arising from a rapid feedforward interneuronal response to focal activity. This response is particularly prominent ahead of an ictal wavefront. Parvalbumin‐positive interneurons are considered to be critically involved in this feedforward inhibition, but it is not known what role, if any, is provided by somatostatin‐expressing interneurons, which target the distal dendrites of pyramidal cells. We used a combination of electrophysiology and cell class‐specific Ca2+ imaging in mouse brain slices bathed in 0 Mg2+ medium to characterize the activity profiles of pyramidal cells and parvalbumin‐ and somatostatin‐expressing interneurons during epileptiform activation. The GCaMP6f signal strongly correlates with the level of activity for both interneuronal classes. Both interneuronal classes participate in the feedfoward inhibition. This contrasts starkly with the pattern of pyramidal recruitment, which is greatly delayed. During these barrages, both sets of interneurons show intense bursting, at rates up to 300Hz, which is time‐locked to the glutamatergic barrages. The activity of parvalbumin‐expressing interneurons appears to peak early in the pre‐ictal period, and can display depolarizing block during the ictal event. In contrast, somatostatin‐expressing interneuronal activity peaks significantly later, and firing persists throughout the ictal events. Interictal events appear to be very similar to the pre‐ictal period, albeit with slightly lower firing rates. Thus, the inhibitory restraint arises from a coordinated pattern of activity in the two main classes of cortical interneurons. There is a rapid interneuronal response to focal activity in cortex, which restrains laterally propagating activity, including spreading epileptiform activity. The interneuronal response involves intense activation of both parvalbumin‐ and somatostatin‐expressing interneurons. Interneuronal bursting is time‐locked to glutamatergic barrages in the pre‐ictal period. Ca2+ imaging using conditional expression of GCaMP6f provides an accurate readout of the evolving firing patterns in both types of interneuron. The activation profiles of the two interneuronal classes are temporally offset, with the parvalbumin population being activated first, and typically, at higher rates.
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Affiliation(s)
- R Ryley Parrish
- Institute of Neuroscience, Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | - Neela K Codadu
- Institute of Neuroscience, Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
| | | | - Andrew J Trevelyan
- Institute of Neuroscience, Medical School, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK
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218
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Jia X, Siegle JH, Bennett C, Gale SD, Denman DJ, Koch C, Olsen SR. High-density extracellular probes reveal dendritic backpropagation and facilitate neuron classification. J Neurophysiol 2019; 121:1831-1847. [PMID: 30840526 DOI: 10.1152/jn.00680.2018] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Different neuron types serve distinct roles in neural processing. Extracellular electrical recordings are extensively used to study brain function but are typically blind to cell identity. Morphoelectrical properties of neurons measured on spatially dense electrode arrays have the potential to distinguish neuron types. We used high-density silicon probes to record from cortical and subcortical regions of the mouse brain. Extracellular waveforms of each neuron were detected across many channels and showed distinct spatiotemporal profiles among brain regions. Classification of neurons by brain region was improved with multichannel compared with single-channel waveforms. In visual cortex, unsupervised clustering identified the canonical regular-spiking (RS) and fast-spiking (FS) classes but also indicated a subclass of RS units with unidirectional backpropagating action potentials (BAPs). Moreover, BAPs were observed in many hippocampal RS cells. Overall, waveform analysis of spikes from high-density probes aids neuron identification and can reveal dendritic backpropagation. NEW & NOTEWORTHY It is challenging to identify neuron types with extracellular electrophysiology in vivo. We show that spatiotemporal action potentials measured on high-density electrode arrays can capture cell type-specific morphoelectrical properties, allowing classification of neurons across brain structures and within the cortex. Moreover, backpropagating action potentials are reliably detected in vivo from subpopulations of cortical and hippocampal neurons. Together, these results enhance the utility of dense extracellular electrophysiology for cell-type interrogation of brain network function.
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Affiliation(s)
- Xiaoxuan Jia
- Allen Institute for Brain Science , Seattle, Washington
| | | | | | - Samuel D Gale
- Allen Institute for Brain Science , Seattle, Washington
| | | | - Christof Koch
- Allen Institute for Brain Science , Seattle, Washington
| | - Shawn R Olsen
- Allen Institute for Brain Science , Seattle, Washington
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219
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Eberhardt F, Herz AVM, Häusler S. Tuft dendrites of pyramidal neurons operate as feedback-modulated functional subunits. PLoS Comput Biol 2019; 15:e1006757. [PMID: 30840615 PMCID: PMC6402658 DOI: 10.1371/journal.pcbi.1006757] [Citation(s) in RCA: 5] [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: 05/08/2018] [Accepted: 01/04/2019] [Indexed: 01/23/2023] Open
Abstract
Dendrites of pyramidal cells exhibit complex morphologies and contain a variety of ionic conductances, which generate non-trivial integrative properties. Basal and proximal apical dendrites have been shown to function as independent computational subunits within a two-layer feedforward processing scheme. The outputs of the subunits are linearly summed and passed through a final non-linearity. It is an open question whether this mathematical abstraction can be applied to apical tuft dendrites as well. Using a detailed compartmental model of CA1 pyramidal neurons and a novel theoretical framework based on iso-response methods, we first show that somatic sub-threshold responses to brief synaptic inputs cannot be described by a two-layer feedforward model. Then, we relax the core assumption of subunit independence and introduce non-linear feedback from the output layer to the subunit inputs. We find that additive feedback alone explains the somatic responses to synaptic inputs to most of the branches in the apical tuft. Individual dendritic branches bidirectionally modulate the thresholds of their input-output curves without significantly changing the gains. In contrast to these findings for precisely timed inputs, we show that neuronal computations based on firing rates can be accurately described by purely feedforward two-layer models. Our findings support the view that dendrites of pyramidal neurons possess non-linear analog processing capabilities that critically depend on the location of synaptic inputs. The iso-response framework proposed in this computational study is highly efficient and could be directly applied to biological neurons. Pyramidal neurons are the principal cell type in the cerebral cortex. Revealing how these cells operate is key to understanding the dynamics and computations of cortical circuits. However, it is still a matter of debate how pyramidal neurons transform their synaptic inputs into spike outputs. Recent studies have proposed that individual dendritic branches or subtrees may function as independent computational subunits. Although experimental work consolidated this abstraction for basal and proximal apical dendrites, a rigorous test for tuft dendrites is still missing. By carrying out a computational study we demonstrate that dendritic branches in the tuft do not form independent subunits, however, their integrative properties can be captured by a model that incorporates modulatory feedback between these subunits. This conclusion has been reached using a novel theoretical framework that can be directly integrated into multi-electrode or photo-stimulation paradigms to reveal the dendritic computations of biological neurons.
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Affiliation(s)
- Florian Eberhardt
- Bernstein Center for Computational Neuroscience Munich, Germany
- Faculty of Biology, Ludwig-Maximilians-Universität München, Germany
| | - Andreas V. M. Herz
- Bernstein Center for Computational Neuroscience Munich, Germany
- Faculty of Biology, Ludwig-Maximilians-Universität München, Germany
| | - Stefan Häusler
- Bernstein Center for Computational Neuroscience Munich, Germany
- Faculty of Biology, Ludwig-Maximilians-Universität München, Germany
- * E-mail:
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220
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Goldwyn JH, Remme MWH, Rinzel J. Soma-axon coupling configurations that enhance neuronal coincidence detection. PLoS Comput Biol 2019; 15:e1006476. [PMID: 30830905 PMCID: PMC6417746 DOI: 10.1371/journal.pcbi.1006476] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 03/14/2019] [Accepted: 01/28/2019] [Indexed: 11/17/2022] Open
Abstract
Coincidence detector neurons transmit timing information by responding preferentially to concurrent synaptic inputs. Principal cells of the medial superior olive (MSO) in the mammalian auditory brainstem are superb coincidence detectors. They encode sound source location with high temporal precision, distinguishing submillisecond timing differences among inputs. We investigate computationally how dynamic coupling between the input region (soma and dendrite) and the spike-generating output region (axon and axon initial segment) can enhance coincidence detection in MSO neurons. To do this, we formulate a two-compartment neuron model and characterize extensively coincidence detection sensitivity throughout a parameter space of coupling configurations. We focus on the interaction between coupling configuration and two currents that provide dynamic, voltage-gated, negative feedback in subthreshold voltage range: sodium current with rapid inactivation and low-threshold potassium current, IKLT. These currents reduce synaptic summation and can prevent spike generation unless inputs arrive with near simultaneity. We show that strong soma-to-axon coupling promotes the negative feedback effects of sodium inactivation and is, therefore, advantageous for coincidence detection. Furthermore, the feedforward combination of strong soma-to-axon coupling and weak axon-to-soma coupling enables spikes to be generated efficiently (few sodium channels needed) and with rapid recovery that enhances high-frequency coincidence detection. These observations detail the functional benefit of the strongly feedforward configuration that has been observed in physiological studies of MSO neurons. We find that IKLT further enhances coincidence detection sensitivity, but with effects that depend on coupling configuration. For instance, in models with weak soma-to-axon and weak axon-to-soma coupling, IKLT in the axon enhances coincidence detection more effectively than IKLT in the soma. By using a minimal model of soma-to-axon coupling, we connect structure, dynamics, and computation. Although we consider the particular case of MSO coincidence detectors, our method for creating and exploring a parameter space of two-compartment models can be applied to other neurons. Brain cells (neurons) are spatially extended structures. The locations at which neurons receive inputs and generate outputs are often distinct. We formulate and study a minimal mathematical model that describes the dynamical coupling between the input and output regions of a neuron. We construct our model to reflect known properties of neurons in the auditory brainstem that play an important role in our ability to locate sound sources. These neurons are known as coincidence detectors because they are most likely to respond when they receive simultaneous inputs. We use simulations to explore coincidence detection sensitivity throughout the parameter space of input-output coupling and to identify the coupling configurations that are best for neural coincidence detection. We find that strong forward coupling (from input region to output region), enhances coincidence detection sensitivity in our model and that low-threshold potassium current further improves coincidence detection. Our study is significant in that we detail how cell structure affects neuronal dynamics and, consequently, the ability of neurons to perform as temporally-precise coincidence detectors.
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Affiliation(s)
- Joshua H Goldwyn
- Department of Mathematics and Statistics, Swarthmore College, Swarthmore, Pennsylvania, United States of America
| | - Michiel W H Remme
- Institute for Theoretical Biology, Humboldt University Berlin, Berlin, Germany
| | - John Rinzel
- Center for Neural Science, New York University, New York, New York, United States of America.,Courant Institute of Mathematical Sciences, New York University, New York, New York, United States of America
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221
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Whittington JCR, Bogacz R. Theories of Error Back-Propagation in the Brain. Trends Cogn Sci 2019; 23:235-250. [PMID: 30704969 PMCID: PMC6382460 DOI: 10.1016/j.tics.2018.12.005] [Citation(s) in RCA: 137] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Revised: 12/13/2018] [Accepted: 12/28/2018] [Indexed: 12/14/2022]
Abstract
This review article summarises recently proposed theories on how neural circuits in the brain could approximate the error back-propagation algorithm used by artificial neural networks. Computational models implementing these theories achieve learning as efficient as artificial neural networks, but they use simple synaptic plasticity rules based on activity of presynaptic and postsynaptic neurons. The models have similarities, such as including both feedforward and feedback connections, allowing information about error to propagate throughout the network. Furthermore, they incorporate experimental evidence on neural connectivity, responses, and plasticity. These models provide insights on how brain networks might be organised such that modification of synaptic weights on multiple levels of cortical hierarchy leads to improved performance on tasks.
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Affiliation(s)
- James C R Whittington
- MRC Brain Network Dynamics Unit, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK; Wellcome Centre for Integrative Neuroimaging, Centre for Functional Magnetic Resonance Imaging of the Brain, University of Oxford, Oxford OX3 9DU, UK
| | - Rafal Bogacz
- MRC Brain Network Dynamics Unit, Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford OX3 9DU, UK.
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222
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Ashhad S, Narayanan R. Stores, Channels, Glue, and Trees: Active Glial and Active Dendritic Physiology. Mol Neurobiol 2019; 56:2278-2299. [PMID: 30014322 PMCID: PMC6394607 DOI: 10.1007/s12035-018-1223-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 07/03/2018] [Indexed: 02/07/2023]
Abstract
Glial cells and neuronal dendrites were historically assumed to be passive structures that play only supportive physiological roles, with no active contribution to information processing in the central nervous system. Research spanning the past few decades has clearly established this assumption to be far from physiological realities. Whereas the discovery of active channel conductances and their localized plasticity was the turning point for dendritic structures, the demonstration that glial cells release transmitter molecules and communicate across the neuroglia syncytium through calcium wave propagation constituted path-breaking discoveries for glial cell physiology. An additional commonality between these two structures is the ability of calcium stores within their endoplasmic reticulum (ER) to support active propagation of calcium waves, which play crucial roles in the spatiotemporal integration of information within and across cells. Although there have been several demonstrations of regulatory roles of glial cells and dendritic structures in achieving common physiological goals such as information propagation and adaptability through plasticity, studies assessing physiological interactions between these two active structures have been few and far. This lacuna is especially striking given the strong connectivity that is known to exist between these two structures through several complex and tightly intercoupled mechanisms that also recruit their respective ER structures. In this review, we present brief overviews of the parallel literatures on active dendrites and active glial physiology and make a strong case for future studies to directly assess the strong interactions between these two structures in regulating physiology and pathophysiology of the brain.
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Affiliation(s)
- Sufyan Ashhad
- Department of Neurobiology, University of California at Los Angeles, Los Angeles, CA, 90095, USA
| | - Rishikesh Narayanan
- Cellular Neurophysiology Laboratory, Molecular Biophysics Unit, Indian Institute of Science, Bangalore, 560012, India.
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223
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Senzai Y, Fernandez-Ruiz A, Buzsáki G. Layer-Specific Physiological Features and Interlaminar Interactions in the Primary Visual Cortex of the Mouse. Neuron 2019; 101:500-513.e5. [PMID: 30635232 PMCID: PMC6367010 DOI: 10.1016/j.neuron.2018.12.009] [Citation(s) in RCA: 141] [Impact Index Per Article: 28.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Revised: 11/27/2018] [Accepted: 12/04/2018] [Indexed: 12/01/2022]
Abstract
The relationship between mesoscopic local field potentials (LFPs) and single-neuron firing in the multi-layered neocortex is poorly understood. Simultaneous recordings from all layers in the primary visual cortex (V1) of the behaving mouse revealed functionally defined layers in V1. The depth of maximum spike power and sink-source distributions of LFPs provided consistent laminar landmarks across animals. Coherence of gamma oscillations (30-100 Hz) and spike-LFP coupling identified six physiological layers and further sublayers. Firing rates, burstiness, and other electrophysiological features of neurons displayed unique layer and brain state dependence. Spike transmission strength from layer 2/3 cells to layer 5 pyramidal cells and interneurons was stronger during waking compared with non-REM sleep but stronger during non-REM sleep among deep-layer excitatory neurons. A subset of deep-layer neurons was active exclusively in the DOWN state of non-REM sleep. These results bridge mesoscopic LFPs and single-neuron interactions with laminar structure in V1.
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Affiliation(s)
- Yuta Senzai
- Neuroscience Institute, New York University, Langone Medical Center, New York, NY 10016, USA
| | - Antonio Fernandez-Ruiz
- Neuroscience Institute, New York University, Langone Medical Center, New York, NY 10016, USA
| | - György Buzsáki
- Neuroscience Institute, New York University, Langone Medical Center, New York, NY 10016, USA; Department of Neurology, Langone Medical Center, New York University, New York, NY 10016, USA; Center for Neural Science, New York University, New York, NY 10003, USA.
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224
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A theory of general intelligence. Med Hypotheses 2019; 123:35-46. [PMID: 30696589 DOI: 10.1016/j.mehy.2018.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 12/01/2018] [Indexed: 11/20/2022]
Abstract
This paper proposes a theoretical framework for the biological learning mechanism as a general learning system. The proposal is as follows. The bursting and tonic modes of firing patterns found in many neuron types in the brain correspond to two separate modes of information processing, with one mode resulting in awareness, and another mode being subliminal. In such a coding scheme, a neuron in bursting state codes for the highest level of perceptual abstraction representing a pattern of sensory stimuli, or volitional abstraction representing a pattern of muscle contraction sequences. Within the 50-250 ms minimum integration time of experience, the bursting neurons form synchrony ensembles to allow for binding of related percepts. The degree which different bursting neurons can be merged into the same synchrony ensemble depends on the underlying cortical connections that represent the degree of perceptual similarity. These synchrony ensembles compete for selective attention to remain active. The dominant synchrony ensemble triggers episodic memory recall in the hippocampus, while forming new episodic memory with current sensory stimuli, resulting in a stream of thoughts. Neuromodulation modulates both top-down selection of synchrony ensembles, and memory formation. Episodic memory stored in the hippocampus is transferred to semantic and procedural memory in the cortex during rapid eye movement sleep, by updating cortical neuron synaptic weights with spike timing dependent plasticity. With the update of synaptic weights, new neurons become bursting while previous bursting neurons become tonic, allowing bursting neurons to move up to a higher level of perceptual abstraction. Finally, the proposed learning mechanism is compared with the back-propagation algorithm used in deep neural networks, and a proposal of how the credit assignment problem can be addressed by the current theory is presented.
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225
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Lam YW, Sherman SM. Convergent synaptic inputs to layer 1 cells of mouse cortex. Eur J Neurosci 2019; 49:1388-1399. [PMID: 30585669 DOI: 10.1111/ejn.14324] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Revised: 12/03/2018] [Accepted: 12/18/2018] [Indexed: 11/30/2022]
Abstract
We used whole cell recordings from slice preparations of mouse cortex to identify various inputs to neurons of layer 1. Two sensory cortical areas were targeted: a primary somatosensory area, namely, the barrel cortex of S1, and a higher order visual area, namely, V2M. Results were similar from both areas. By activating local inputs using photostimulation with caged glutamate, we also identified glutamatergic (and possibly GABAergic) inputs from all lower layers plus GABAergic inputs from nearby layer 1 neurons. However, the patterns of such inputs to layer 1 neurons showed great variation among cells. In separate experiments, we found that electrical stimulation of axons running parallel to the cortical surface in layer 1 also evoked a variety of convergent input types to layer 1 neurons, including glutamatergic "drivers" and "modulators" plus classic modulatory inputs, including serotonergic, nicotinic, α- and β-adrenergic, from subcortical sites. Given that these layer 1 cells significantly affect the responses of other cortical neurons, especially via affecting the apical dendrites of pyramidal cells so important to cortical functioning, their role in cortical processing is significant. We believe that the data presented here lead to better understanding of the functioning of layer 1 neurons in their role of influencing cortical processing.
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Affiliation(s)
- Ying-Wan Lam
- Department of Neurobiology, University of Chicago, Chicago, Illinois
| | - S Murray Sherman
- Department of Neurobiology, University of Chicago, Chicago, Illinois
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226
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Layer 3 Dynamically Coordinates Columnar Activity According to Spatial Context. J Neurosci 2019; 39:281-294. [PMID: 30459226 DOI: 10.1523/jneurosci.1568-18.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 10/16/2018] [Accepted: 10/16/2018] [Indexed: 01/03/2023] Open
Abstract
To reduce statistical redundancy of natural inputs and increase the sparseness of coding, neurons in primary visual cortex (V1) show tuning for stimulus size and surround suppression. This integration of spatial information is a fundamental, context-dependent neural operation involving extensive neural circuits that span across all cortical layers of a V1 column, and reflects both feedforward and feedback processing. However, how spatial integration is dynamically coordinated across cortical layers remains poorly understood. We recorded single- and multiunit activity and local field potentials across V1 layers of awake mice (both sexes) while they viewed stimuli of varying size and used dynamic Bayesian model comparisons to identify when laminar activity and interlaminar functional interactions showed surround suppression, the hallmark of spatial integration. We found that surround suppression is strongest in layer 3 (L3) and L4 activity, where suppression is established within ∼10 ms after response onset, and receptive fields dynamically sharpen while suppression strength increases. Importantly, we also found that specific directed functional connections were strongest for intermediate stimulus sizes and suppressed for larger ones, particularly for connections from L3 targeting L5 and L1. Together, the results shed light on the different functional roles of cortical layers in spatial integration and on how L3 dynamically coordinates activity across a cortical column depending on spatial context.SIGNIFICANCE STATEMENT Neurons in primary visual cortex (V1) show tuning for stimulus size, where responses to stimuli exceeding the receptive field can be suppressed (surround suppression). We demonstrate that functional connectivity between V1 layers can also have a surround-suppressed profile. A particularly prominent role seems to have layer 3, the functional connections to layers 5 and 1 of which are strongest for stimuli of optimal size and decreased for large stimuli. Our results therefore point toward a key role of layer 3 in coordinating activity across the cortical column according to spatial context.
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227
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Fletcher LN, Williams SR. Neocortical Topology Governs the Dendritic Integrative Capacity of Layer 5 Pyramidal Neurons. Neuron 2019; 101:76-90.e4. [DOI: 10.1016/j.neuron.2018.10.048] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Revised: 08/03/2018] [Accepted: 10/25/2018] [Indexed: 10/27/2022]
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228
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Williams SR, Fletcher LN. A Dendritic Substrate for the Cholinergic Control of Neocortical Output Neurons. Neuron 2018; 101:486-499.e4. [PMID: 30594427 DOI: 10.1016/j.neuron.2018.11.035] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 10/29/2018] [Accepted: 11/19/2018] [Indexed: 11/17/2022]
Abstract
The ascending cholinergic system dynamically regulates sensory perception and cognitive function, but it remains unclear how this modulation is executed in neocortical circuits. Here, we demonstrate that the cholinergic system controls the integrative operations of neocortical principal neurons by modulating dendritic excitability. Direct dendritic recordings revealed that the optogenetic-evoked release of acetylcholine (ACh) transformed the pattern of dendritic integration in layer 5B pyramidal neurons, leading to the generation of dendritic plateau potentials which powerfully drove repetitive action potential output. In contrast, the synaptic release of ACh did not positively modulate axo-somatic excitability. Mechanistically, the transformation of dendritic integration was mediated by the muscarinic ACh receptor-dependent enhancement of dendritic R-type calcium channel activity, a compartment-dependent modulation which decisively controlled the associative computations executed by layer 5B pyramidal neurons. Our findings therefore reveal a biophysical mechanism by which the cholinergic system controls dendritic computations causally linked to perceptual detection.
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Affiliation(s)
- Stephen R Williams
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
| | - Lee N Fletcher
- Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia
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229
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Górski T, Veltz R, Galtier M, Fragnaud H, Goldman JS, Teleńczuk B, Destexhe A. Dendritic sodium spikes endow neurons with inverse firing rate response to correlated synaptic activity. J Comput Neurosci 2018; 45:223-234. [PMID: 30547292 PMCID: PMC6306432 DOI: 10.1007/s10827-018-0707-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 10/30/2018] [Accepted: 11/06/2018] [Indexed: 11/28/2022]
Abstract
Many neurons possess dendrites enriched with sodium channels and are capable of generating action potentials. However, the role of dendritic sodium spikes remain unclear. Here, we study computational models of neurons to investigate the functional effects of dendritic spikes. In agreement with previous studies, we found that point neurons or neurons with passive dendrites increase their somatic firing rate in response to the correlation of synaptic bombardment for a wide range of input conditions, i.e. input firing rates, synaptic conductances, or refractory periods. However, neurons with active dendrites show the opposite behavior: for a wide range of conditions the firing rate decreases as a function of correlation. We found this property in three types of models of dendritic excitability: a Hodgkin-Huxley model of dendritic spikes, a model with integrate and fire dendrites, and a discrete-state dendritic model. We conclude that fast dendritic spikes confer much broader computational properties to neurons, sometimes opposite to that of point neurons.
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Affiliation(s)
- Tomasz Górski
- Unité de Neurosciences, Information et Complexité, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France. .,European Institute for Theoretical Neuroscience, Paris, France.
| | | | - Mathieu Galtier
- Unité de Neurosciences, Information et Complexité, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
| | - Hélissande Fragnaud
- Unité de Neurosciences, Information et Complexité, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France
| | - Jennifer S Goldman
- Unité de Neurosciences, Information et Complexité, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France.,European Institute for Theoretical Neuroscience, Paris, France
| | - Bartosz Teleńczuk
- Unité de Neurosciences, Information et Complexité, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France.,European Institute for Theoretical Neuroscience, Paris, France
| | - Alain Destexhe
- Unité de Neurosciences, Information et Complexité, Centre National de la Recherche Scientifique, Gif-sur-Yvette, France.,European Institute for Theoretical Neuroscience, Paris, France
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230
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Wang Y, Ye M, Kuang X, Li Y, Hu S. A simplified morphological classification scheme for pyramidal cells in six layers of primary somatosensory cortex of juvenile rats. IBRO Rep 2018; 5:74-90. [PMID: 30450442 PMCID: PMC6222978 DOI: 10.1016/j.ibror.2018.10.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 10/08/2018] [Accepted: 10/09/2018] [Indexed: 01/01/2023] Open
Abstract
The majority of neurons in the neocortex are excitatory pyramidal cells (PCs). Many systematic classification schemes have been proposed based the neuronal morphology, the chemical composition, and the synaptic connectivity, etc. Recently, a cortical column of primary somatosensory cortex (SSC) has been reconstruction and functionally simulated (Markram et al., 2015). Putting forward from this study, here we proposed a simplified classification scheme for PCs in all layers of the SSC by mainly identifying apical dendritic morphology based on a large data set of 3D neuron reconstructions. We used this scheme to classify three types in layer 2, two in layer 3, three in layer 4, four in layer 5, and six types in layer 6. These PC types were visually distinguished and confirmed by quantitative differences in their morphometric properties. The classes yielded using this scheme largely corresponded with PC classes that were defined previously based on other neuronal and synaptic properties such as long-range projects and synaptic innervations, further validating its applicability. Therefore, the morphology information of apical dendrites is sufficient for a simple scheme to classify a spectrum of anatomical types of PCs in the SSC.
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Affiliation(s)
- Yun Wang
- School of Optometry & Ophthalmology, Wenzhou Medical University, Wenzhou, Zhejiang, P. R. China
- Allen Institute for Brain Science, Seattle, WA, USA
| | - Min Ye
- School of Optometry & Ophthalmology, Wenzhou Medical University, Wenzhou, Zhejiang, P. R. China
| | - Xiuli Kuang
- School of Optometry & Ophthalmology, Wenzhou Medical University, Wenzhou, Zhejiang, P. R. China
| | - Yaoyao Li
- School of Optometry & Ophthalmology, Wenzhou Medical University, Wenzhou, Zhejiang, P. R. China
| | - Shisi Hu
- School of Optometry & Ophthalmology, Wenzhou Medical University, Wenzhou, Zhejiang, P. R. China
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231
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Yi G, Wei X, Wang J, Deng B, Che Y. Modulations of dendritic Ca 2+ spike with weak electric fields in layer 5 pyramidal cells. Neural Netw 2018; 110:8-18. [PMID: 30471543 DOI: 10.1016/j.neunet.2018.10.013] [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: 02/27/2018] [Revised: 09/23/2018] [Accepted: 10/26/2018] [Indexed: 01/01/2023]
Abstract
Weak electric fields (EFs) modulate input/output function of pyramidal cells. Dendritic Ca2+ spike is an important cellular mechanism for coupling synaptic inputs from different cortical layers, which plays a critical role in neuronal computation. This study aims to understand the effects of weak EFs on Ca2+ spikes initiated in the distal dendrites. We use a computational model to simulate dendritic Ca2+ spikes and backpropagating action potentials (APs) in layer 5 pyramidal cells. We apply uniform EFs (less than 20 mV/mm) to the model and examine how they affect the threshold for activation of Ca2+ spikes. We show that the effects of weak field on synaptically evoked Ca2+ spikes depend on the timing of synaptic inputs. When distal inputs coincide with the onset of EFs within a time window of several milliseconds, field-induced depolarization facilitates the initiation of Ca2+ spikes, while field-induced hyperpolarization suppresses dendritic APs. Sustained field-induced depolarization leads to the inactivation of Ca2+ channels and increases the threshold of Ca2+ spike. Sustained field-induced hyperpolarization de-inactivates Ca2+ channels and reduces the threshold of Ca2+ spike. By altering the threshold of backpropagation activated Ca2+ firing, field-induced depolarization increases the degree of coupling between inputs of the soma and distal dendrites, while field-induced hyperpolarization results in a decrease of coupling. The modulatory effects of weak EF are governed by the field direction with respect to the cell. Our study explains a fundamental link between field-induced polarization, dendritic Ca2+ spike, and somato-dendritic coupling. The findings are crucial to interpret how weak EFs achieve specific modulation of cellular activity.
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Affiliation(s)
- Guosheng Yi
- School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, China
| | - Xile Wei
- School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, China.
| | - Jiang Wang
- School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, China
| | - Bin Deng
- School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, China
| | - Yanqiu Che
- School of Automation and Electrical Engineering, Tianjin University of Technology and Education, Tianjin 300222, China.
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232
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Takahashi N. Synaptic topography - Converging connections and emerging function. Neurosci Res 2018; 141:29-35. [PMID: 30468748 DOI: 10.1016/j.neures.2018.11.001] [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] [Received: 03/31/2018] [Revised: 10/16/2018] [Accepted: 11/01/2018] [Indexed: 11/25/2022]
Abstract
Brain circuits are constituted of individual neurons that are interconnected with a vast array of synapses. In order to understand how brain function emerges from this complex synaptic network, immense efforts have been made to trace the synaptic topography, i.e. arrangement of synaptic connections, of the network. In addition to anatomically elaborating the synaptic layout at multiple levels across brain regions, recent studies have attempted to elucidate the fundamental wiring principles that govern neural information processing in the brain, establishing a link between anatomy and function. In this review, I will discuss recent discoveries on the topographical organization of synaptic connections at the cell-to-cell and subcellular levels in the cortex and hippocampus. Accumulating evidence leads us to acknowledge the highly structured, non-random synaptic connectivity that emerges together with sensory feature preferences of neurons and synchronous neuronal activity.
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Affiliation(s)
- Naoya Takahashi
- Institute for Biology, Neuronal Plasticity, Humboldt University of Berlin, D-10117, Berlin, Germany.
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233
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Ranganathan GN, Apostolides PF, Harnett MT, Xu NL, Druckmann S, Magee JC. Active dendritic integration and mixed neocortical network representations during an adaptive sensing behavior. Nat Neurosci 2018; 21:1583-1590. [PMID: 30349100 PMCID: PMC6203624 DOI: 10.1038/s41593-018-0254-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Accepted: 09/13/2018] [Indexed: 02/08/2023]
Abstract
Animals strategically scan the environment to form an accurate perception of their surroundings. Here we investigated the neuronal representations that mediate this behavior. Ca2+ imaging and selective optogenetic manipulation during an active sensing task reveals that layer 5 pyramidal neurons in the vibrissae cortex produce a diverse and distributed representation that is required for mice to adapt their whisking motor strategy to changing sensory cues. The optogenetic perturbation degraded single-neuron selectivity and network population encoding through a selective inhibition of active dendritic integration. Together the data indicate that active dendritic integration in pyramidal neurons produces a nonlinearly mixed network representation of joint sensorimotor parameters that is used to transform sensory information into motor commands during adaptive behavior. The prevalence of the layer 5 cortical circuit motif suggests that this is a general circuit computation.
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Affiliation(s)
| | - Pierre F Apostolides
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA, USA.,Kresge Hearing Research Institute Department of Otolaryngology, University of Michigan , Ann Arbor, MI, USA
| | - Mark T Harnett
- McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Ning-Long Xu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, CAS Center for Excellence in Brain Science and Intelligence Technology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai, China
| | - Shaul Druckmann
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA, USA
| | - Jeffrey C Magee
- Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA, USA. .,Howard Hughes Medical Institute, Baylor College of Medicine, Houston, TX, USA.
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234
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Learning-Related Plasticity in Dendrite-Targeting Layer 1 Interneurons. Neuron 2018; 100:684-699.e6. [PMID: 30269988 PMCID: PMC6226614 DOI: 10.1016/j.neuron.2018.09.001] [Citation(s) in RCA: 117] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 08/09/2018] [Accepted: 08/31/2018] [Indexed: 11/23/2022]
Abstract
A wealth of data has elucidated the mechanisms by which sensory inputs are encoded in the neocortex, but how these processes are regulated by the behavioral relevance of sensory information is less understood. Here, we focus on neocortical layer 1 (L1), a key location for processing of such top-down information. Using Neuron-Derived Neurotrophic Factor (NDNF) as a selective marker of L1 interneurons (INs) and in vivo 2-photon calcium imaging, electrophysiology, viral tracing, optogenetics, and associative memory, we find that L1 NDNF-INs mediate a prolonged form of inhibition in distal pyramidal neuron dendrites that correlates with the strength of the memory trace. Conversely, inhibition from Martinotti cells remains unchanged after conditioning but in turn tightly controls sensory responses in NDNF-INs. These results define a genetically addressable form of dendritic inhibition that is highly experience dependent and indicate that in addition to disinhibition, salient stimuli are encoded at elevated levels of distal dendritic inhibition. Video Abstract
NDNF is a selective marker for neocortical layer 1 interneurons NDNF interneurons mediate prolonged inhibition of distal pyramidal neuron dendrites Inhibition from Martinotti cells tightly controls NDNF interneuron responses Dendritic inhibition by NDNF interneurons is highly experience dependent
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235
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Abstract
We summarize evidence that input to the apical tufts of neocortical pyramidal cells modulates their response to basal input. Because this apical amplification and disamplification provide intracortical mechanisms for prioritization, Mather and colleagues' arguments suggest that their effects are enhanced by noradrenergic arousal. Though that is likely, it has not yet been adequately studied. Their article shows that it should be.
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236
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Richards BA, Lillicrap TP. Dendritic solutions to the credit assignment problem. Curr Opin Neurobiol 2018; 54:28-36. [PMID: 30205266 DOI: 10.1016/j.conb.2018.08.003] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Revised: 07/19/2018] [Accepted: 08/07/2018] [Indexed: 11/27/2022]
Abstract
Guaranteeing that synaptic plasticity leads to effective learning requires a means for assigning credit to each neuron for its contribution to behavior. The 'credit assignment problem' refers to the fact that credit assignment is non-trivial in hierarchical networks with multiple stages of processing. One difficulty is that if credit signals are integrated with other inputs, then it is hard for synaptic plasticity rules to distinguish credit-related activity from non-credit-related activity. A potential solution is to use the spatial layout and non-linear properties of dendrites to distinguish credit signals from other inputs. In cortical pyramidal neurons, evidence hints that top-down feedback signals are integrated in the distal apical dendrites and have a distinct impact on spike-firing and synaptic plasticity. This suggests that the distal apical dendrites of pyramidal neurons help the brain to solve the credit assignment problem.
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Affiliation(s)
- Blake A Richards
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada; Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada; Learning in Machines and Brains Program, Canadian Institute for Advanced Research, Toronto, ON, Canada
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237
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Martinolli M, Gerstner W, Gilra A. Multi-Timescale Memory Dynamics Extend Task Repertoire in a Reinforcement Learning Network With Attention-Gated Memory. Front Comput Neurosci 2018; 12:50. [PMID: 30061819 PMCID: PMC6055065 DOI: 10.3389/fncom.2018.00050] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 06/18/2018] [Indexed: 11/13/2022] Open
Abstract
The interplay of reinforcement learning and memory is at the core of several recent neural network models, such as the Attention-Gated MEmory Tagging (AuGMEnT) model. While successful at various animal learning tasks, we find that the AuGMEnT network is unable to cope with some hierarchical tasks, where higher-level stimuli have to be maintained over a long time, while lower-level stimuli need to be remembered and forgotten over a shorter timescale. To overcome this limitation, we introduce a hybrid AuGMEnT, with leaky (or short-timescale) and non-leaky (or long-timescale) memory units, that allows the exchange of low-level information while maintaining high-level one. We test the performance of the hybrid AuGMEnT network on two cognitive reference tasks, sequence prediction and 12AX.
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Affiliation(s)
- Marco Martinolli
- School of Computer and Communication Sciences, School of Life Sciences, Brain-Mind Institute, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Wulfram Gerstner
- School of Computer and Communication Sciences, School of Life Sciences, Brain-Mind Institute, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Aditya Gilra
- School of Computer and Communication Sciences, School of Life Sciences, Brain-Mind Institute, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
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238
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Larkum ME, Petro LS, Sachdev RNS, Muckli L. A Perspective on Cortical Layering and Layer-Spanning Neuronal Elements. Front Neuroanat 2018; 12:56. [PMID: 30065634 PMCID: PMC6056619 DOI: 10.3389/fnana.2018.00056] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 06/19/2018] [Indexed: 02/03/2023] Open
Abstract
This review article addresses the function of the layers of the cerebral cortex. We develop the perspective that cortical layering needs to be understood in terms of its functional anatomy, i.e., the terminations of synaptic inputs on distinct cellular compartments and their effect on cortical activity. The cortex is a hierarchical structure in which feed forward and feedback pathways have a layer-specific termination pattern. We take the view that the influence of synaptic inputs arriving at different cortical layers can only be understood in terms of their complex interaction with cellular biophysics and the subsequent computation that occurs at the cellular level. We use high-resolution fMRI, which can resolve activity across layers, as a case study for implementing this approach by describing how cognitive events arising from the laminar distribution of inputs can be interpreted by taking into account the properties of neurons that span different layers. This perspective is based on recent advances in measuring subcellular activity in distinct feed-forward and feedback axons and in dendrites as they span across layers.
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Affiliation(s)
- Matthew E Larkum
- Neurocure Center for Excellence, Charité Universitätsmedizin Berlin & Humboldt Universität, Berlin, Germany
| | - Lucy S Petro
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom
| | - Robert N S Sachdev
- Neurocure Center for Excellence, Charité Universitätsmedizin Berlin & Humboldt Universität, Berlin, Germany
| | - Lars Muckli
- Centre for Cognitive Neuroimaging, Institute of Neuroscience and Psychology, University of Glasgow, Glasgow, United Kingdom
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239
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Mansvelder HD, Verhoog MB, Goriounova NA. Synaptic plasticity in human cortical circuits: cellular mechanisms of learning and memory in the human brain? Curr Opin Neurobiol 2018; 54:186-193. [PMID: 30017789 DOI: 10.1016/j.conb.2018.06.013] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 06/19/2018] [Accepted: 06/30/2018] [Indexed: 12/18/2022]
Abstract
Synaptic plasticity is the cellular basis of learning and memory, but to what extent this holds for the adult human brain is not known. To study synaptic plasticity in human neuronal circuits poses a huge challenge, since live human neurons and synapses are not readily accessible. Despite this, various lines of research have provided insights in properties of adult human synapses and their plasticity both in vitro and in vivo, with some unexpected surprises. We first discuss the experimental approaches to study activity-dependent plasticity of adult human synapses, and then highlight rules and mechanisms of Hebbian spike timing-dependent plasticity (STDP) found in these synapses. Finally, we conclude with thoughts on how these synaptic principles can underlie human learning and memory.
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Affiliation(s)
- Huibert D Mansvelder
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Neuroscience Amsterdam, VU University Amsterdam, The Netherlands.
| | - Matthijs B Verhoog
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Neuroscience Amsterdam, VU University Amsterdam, The Netherlands; Division of Cell Biology, Department of Human Biology, Neuroscience Institute, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Natalia A Goriounova
- Department of Integrative Neurophysiology, Center for Neurogenomics and Cognitive Research, Neuroscience Amsterdam, VU University Amsterdam, The Netherlands
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240
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Zeldenrust F, Wadman WJ, Englitz B. Neural Coding With Bursts-Current State and Future Perspectives. Front Comput Neurosci 2018; 12:48. [PMID: 30034330 PMCID: PMC6043860 DOI: 10.3389/fncom.2018.00048] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 06/06/2018] [Indexed: 12/11/2022] Open
Abstract
Neuronal action potentials or spikes provide a long-range, noise-resistant means of communication between neurons. As point processes single spikes contain little information in themselves, i.e., outside the context of spikes from other neurons. Moreover, they may fail to cross a synapse. A burst, which consists of a short, high frequency train of spikes, will more reliably cross a synapse, increasing the likelihood of eliciting a postsynaptic spike, depending on the specific short-term plasticity at that synapse. Both the number and the temporal pattern of spikes in a burst provide a coding space that lies within the temporal integration realm of single neurons. Bursts have been observed in many species, including the non-mammalian, and in brain regions that range from subcortical to cortical. Despite their widespread presence and potential relevance, the uncertainties of how to classify bursts seems to have limited the research into the coding possibilities for bursts. The present series of research articles provides new insights into the relevance and interpretation of bursts across different neural circuits, and new methods for their analysis. Here, we provide a succinct introduction to the history of burst coding and an overview of recent work on this topic.
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Affiliation(s)
- Fleur Zeldenrust
- Department of Neurophysiology, Donders Institute for Brain, Cognition, and Behaviour, Radboud University, Nijmegen, Netherlands
| | - Wytse J Wadman
- Cellular and Systems Neurobiology Lab, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands
| | - Bernhard Englitz
- Department of Neurophysiology, Donders Institute for Brain, Cognition, and Behaviour, Radboud University, Nijmegen, Netherlands
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241
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Naud R, Sprekeler H. Sparse bursts optimize information transmission in a multiplexed neural code. Proc Natl Acad Sci U S A 2018; 115:E6329-E6338. [PMID: 29934400 PMCID: PMC6142200 DOI: 10.1073/pnas.1720995115] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Many cortical neurons combine the information ascending and descending the cortical hierarchy. In the classical view, this information is combined nonlinearly to give rise to a single firing-rate output, which collapses all input streams into one. We analyze the extent to which neurons can simultaneously represent multiple input streams by using a code that distinguishes spike timing patterns at the level of a neural ensemble. Using computational simulations constrained by experimental data, we show that cortical neurons are well suited to generate such multiplexing. Interestingly, this neural code maximizes information for short and sparse bursts, a regime consistent with in vivo recordings. Neurons can also demultiplex this information, using specific connectivity patterns. The anatomy of the adult mammalian cortex suggests that these connectivity patterns are used by the nervous system to maintain sparse bursting and optimal multiplexing. Contrary to firing-rate coding, our findings indicate that the physiology and anatomy of the cortex may be interpreted as optimizing the transmission of multiple independent signals to different targets.
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Affiliation(s)
- Richard Naud
- University of Ottawa Brain and Mind Research Institute, Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON K1H 8M5, Canada;
- Department of Physics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Henning Sprekeler
- Bernstein Center for Computational Neuroscience Berlin, 10115 Berlin, Germany
- Modelling of Cognitive Processes, Institute of Software Engineering and Theoretical Computer Science, Technische Universität Berlin, 10587 Berlin, Germany
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242
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Eyal G, Verhoog MB, Testa-Silva G, Deitcher Y, Benavides-Piccione R, DeFelipe J, de Kock CPJ, Mansvelder HD, Segev I. Human Cortical Pyramidal Neurons: From Spines to Spikes via Models. Front Cell Neurosci 2018; 12:181. [PMID: 30008663 PMCID: PMC6034553 DOI: 10.3389/fncel.2018.00181] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 06/08/2018] [Indexed: 12/19/2022] Open
Abstract
We present detailed models of pyramidal cells from human neocortex, including models on their excitatory synapses, dendritic spines, dendritic NMDA- and somatic/axonal Na+ spikes that provided new insights into signal processing and computational capabilities of these principal cells. Six human layer 2 and layer 3 pyramidal cells (HL2/L3 PCs) were modeled, integrating detailed anatomical and physiological data from both fresh and postmortem tissues from human temporal cortex. The models predicted particularly large AMPA- and NMDA-conductances per synaptic contact (0.88 and 1.31 nS, respectively) and a steep dependence of the NMDA-conductance on voltage. These estimates were based on intracellular recordings from synaptically-connected HL2/L3 pairs, combined with extra-cellular current injections and use of synaptic blockers, and the assumption of five contacts per synaptic connection. A large dataset of high-resolution reconstructed HL2/L3 dendritic spines provided estimates for the EPSPs at the spine head (12.7 ± 4.6 mV), spine base (9.7 ± 5.0 mV), and soma (0.3 ± 0.1 mV), and for the spine neck resistance (50–80 MΩ). Matching the shape and firing pattern of experimental somatic Na+-spikes provided estimates for the density of the somatic/axonal excitable membrane ion channels, predicting that 134 ± 28 simultaneously activated HL2/L3-HL2/L3 synapses are required for generating (with 50% probability) a somatic Na+ spike. Dendritic NMDA spikes were triggered in the model when 20 ± 10 excitatory spinous synapses were simultaneously activated on individual dendritic branches. The particularly large number of basal dendrites in HL2/L3 PCs and the distinctive cable elongation of their terminals imply that ~25 NMDA-spikes could be generated independently and simultaneously in these cells, as compared to ~14 in L2/3 PCs from the rat somatosensory cortex. These multi-sites non-linear signals, together with the large (~30,000) excitatory synapses/cell, equip human L2/L3 PCs with enhanced computational capabilities. Our study provides the most comprehensive model of any human neuron to-date demonstrating the biophysical and computational distinctiveness of human cortical neurons.
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Affiliation(s)
- Guy Eyal
- Department of Neurobiology, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Matthijs B Verhoog
- Department of Integrative Neurophysiology, Centre for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam, Amsterdam, Netherlands.,Department of Human Biology, Neuroscience Institute, University of Cape Town, Cape Town, South Africa
| | - Guilherme Testa-Silva
- Department of Integrative Neurophysiology, Centre for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam, Amsterdam, Netherlands
| | - Yair Deitcher
- Edmond and Lily Safra Center for Brain Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
| | - Ruth Benavides-Piccione
- Departamento de Neurobiología Funcional y de Sistemas, Instituto Cajal (CSIC), and Laboratorio Cajal de Circuitos Corticales (CTB), Universidad Politécnica de Madrid, Madrid, Spain
| | - Javier DeFelipe
- Departamento de Neurobiología Funcional y de Sistemas, Instituto Cajal (CSIC), and Laboratorio Cajal de Circuitos Corticales (CTB), Universidad Politécnica de Madrid, Madrid, Spain
| | - Christiaan P J de Kock
- Department of Integrative Neurophysiology, Centre for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam, Amsterdam, Netherlands
| | - Huibert D Mansvelder
- Department of Integrative Neurophysiology, Centre for Neurogenomics and Cognitive Research, Amsterdam Neuroscience, VU University Amsterdam, Amsterdam, Netherlands
| | - Idan Segev
- Department of Neurobiology, Hebrew University of Jerusalem, Jerusalem, Israel.,Edmond and Lily Safra Center for Brain Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
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243
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Doron M, Chindemi G, Muller E, Markram H, Segev I. Timed Synaptic Inhibition Shapes NMDA Spikes, Influencing Local Dendritic Processing and Global I/O Properties of Cortical Neurons. Cell Rep 2018; 21:1550-1561. [PMID: 29117560 DOI: 10.1016/j.celrep.2017.10.035] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2017] [Revised: 08/17/2017] [Accepted: 10/08/2017] [Indexed: 10/18/2022] Open
Abstract
The NMDA spike is a long-lasting nonlinear phenomenon initiated locally in the dendritic branches of a variety of cortical neurons. It plays a key role in synaptic plasticity and in single-neuron computations. Combining dynamic system theory and computational approaches, we now explore how the timing of synaptic inhibition affects the NMDA spike and its associated membrane current. When impinging on its early phase, individual inhibitory synapses strongly, but transiently, dampen the NMDA spike; later inhibition prematurely terminates it. A single inhibitory synapse reduces the NMDA-mediated Ca2+ current, a key player in plasticity, by up to 45%. NMDA spikes in distal dendritic branches/spines are longer-lasting and more resilient to inhibition, enhancing synaptic plasticity at these branches. We conclude that NMDA spikes are highly sensitive to dendritic inhibition; sparse weak inhibition can finely tune synaptic plasticity both locally at the dendritic branch level and globally at the level of the neuron's output.
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Affiliation(s)
- Michael Doron
- Edmond and Lily Safra Center for Brain Sciences, the Hebrew University of Jerusalem, Jerusalem 91904, Israel.
| | - Giuseppe Chindemi
- Blue Brain Project, École polytechnique fédérale de Lausanne (EPFL), Biotech Campus, 1202 Geneva, Switzerland
| | - Eilif Muller
- Blue Brain Project, École polytechnique fédérale de Lausanne (EPFL), Biotech Campus, 1202 Geneva, Switzerland
| | - Henry Markram
- Blue Brain Project, École polytechnique fédérale de Lausanne (EPFL), Biotech Campus, 1202 Geneva, Switzerland
| | - Idan Segev
- Edmond and Lily Safra Center for Brain Sciences, the Hebrew University of Jerusalem, Jerusalem 91904, Israel; Department of Neurobiology, the Hebrew University of Jerusalem, Jerusalem 91904, Israel
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244
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Hsu CL, Zhao X, Milstein AD, Spruston N. Persistent Sodium Current Mediates the Steep Voltage Dependence of Spatial Coding in Hippocampal Pyramidal Neurons. Neuron 2018; 99:147-162.e8. [PMID: 29909995 DOI: 10.1016/j.neuron.2018.05.025] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Revised: 04/13/2018] [Accepted: 05/14/2018] [Indexed: 01/19/2023]
Abstract
The mammalian hippocampus forms a cognitive map using neurons that fire according to an animal's position ("place cells") and many other behavioral and cognitive variables. The responses of these neurons are shaped by their presynaptic inputs and the nature of their postsynaptic integration. In CA1 pyramidal neurons, spatial responses in vivo exhibit a strikingly supralinear dependence on baseline membrane potential. The biophysical mechanisms underlying this nonlinear cellular computation are unknown. Here, through a combination of in vitro, in vivo, and in silico approaches, we show that persistent sodium current mediates the strong membrane potential dependence of place cell activity. This current operates at membrane potentials below the action potential threshold and over seconds-long timescales, mediating a powerful and rapidly reversible amplification of synaptic responses, which drives place cell firing. Thus, we identify a biophysical mechanism that shapes the coding properties of neurons composing the hippocampal cognitive map.
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Affiliation(s)
- Ching-Lung Hsu
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Xinyu Zhao
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA
| | - Aaron D Milstein
- Neurosurgery Department, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Nelson Spruston
- Janelia Research Campus, Howard Hughes Medical Institute, Ashburn, VA 20147, USA.
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245
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Chang JT, Higley MJ. Potassium channels contribute to activity-dependent regulation of dendritic inhibition. Physiol Rep 2018; 6:e13747. [PMID: 29939492 PMCID: PMC6016672 DOI: 10.14814/phy2.13747] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 05/29/2018] [Indexed: 11/24/2022] Open
Abstract
GABAergic inhibition plays a critical role in the regulation of neuronal activity. In the neocortex, inhibitory interneurons that target the dendrites of pyramidal cells influence both electrical and biochemical postsynaptic signaling. Voltage-gated ion channels strongly shape dendritic excitability and the integration of excitatory inputs, but their contribution to GABAergic signaling is less well understood. By combining 2-photon calcium imaging and focal GABA uncaging, we show that voltage-gated potassium channels normally suppress the GABAergic inhibition of calcium signals evoked by back-propagating action potentials in dendritic spines and shafts of cortical pyramidal neurons. Moreover, the voltage-dependent inactivation of these channels leads to enhancement of dendritic calcium inhibition following somatic spiking. Computational modeling reveals that the enhancement of calcium inhibition involves an increase in action potential depolarization coupled with the nonlinear relationship between membrane voltage and calcium channel activation. Overall, our findings highlight the interaction between intrinsic and synaptic properties and reveal a novel mechanism for the activity-dependent regulation of GABAergic inhibition.
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Affiliation(s)
- Jeremy T. Chang
- Department of NeuroscienceProgram in Cellular Neuroscience, Neurodegeneration and RepairKavli InstituteYale School of MedicineNew HavenConnecticut
| | - Michael J. Higley
- Department of NeuroscienceProgram in Cellular Neuroscience, Neurodegeneration and RepairKavli InstituteYale School of MedicineNew HavenConnecticut
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246
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Yang S, Chung J, Jin SH, Bao S, Yang S. A circuit mechanism of time-to-space conversion for perception. Hear Res 2018; 366:32-37. [PMID: 29804722 DOI: 10.1016/j.heares.2018.05.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Revised: 05/08/2018] [Accepted: 05/14/2018] [Indexed: 12/13/2022]
Abstract
Sensory information in a temporal sequence is processed as a collective unit by the nervous system. The cellular mechanisms underlying how sequential inputs are incorporated into the brain has emerged as an important subject in neuroscience. Here, we hypothesize that information-bearing (IB) signals can be entrained and amplified by a clock signal, allowing them to efficiently propagate along in a feedforward circuit. IB signals can remain latent on individual dendrites of the receiving neurons until they are read out by an oscillatory clock signal. In such a way, the IB signals pass through the next neurons along a linear chain. This hypothesis identifies a cellular process of time-to-space and sound-to-map conversion in primary auditory cortex, providing insight into a mechanistic principle underlying the representation and memory of temporal sequences of information.
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Affiliation(s)
- Sunggu Yang
- Department of Nano-bioengineering, Incheon National University, Incheon, 22012, South Korea.
| | - Jaeyong Chung
- Department of Electronics Engineering, Incheon National University, Incheon, 22012, South Korea
| | - Sung Hun Jin
- Department of Electronics Engineering, Incheon National University, Incheon, 22012, South Korea
| | - Shaowen Bao
- Department of Physiology, University of Arizona, Tucson, AZ 85724, USA.
| | - Sungchil Yang
- Department of Biomedical Sciences, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong.
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247
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Miriyala A, Kessler S, Rind FC, Wright GA. Burst Firing in Bee Gustatory Neurons Prevents Adaptation. Curr Biol 2018; 28:1585-1594.e3. [PMID: 29754900 DOI: 10.1016/j.cub.2018.03.070] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Revised: 02/20/2018] [Accepted: 03/29/2018] [Indexed: 10/16/2022]
Abstract
Animals detect changes in the environment using modality-specific, peripheral sensory neurons. The insect gustatory system encodes tastant identity and concentration through the independent firing of gustatory receptor neurons (GRNs) that spike rapidly at stimulus onset and quickly adapt. Here, we show the first evidence that concentrated sugar evokes a temporally structured burst pattern of spiking involving two GRNs within the gustatory sensilla of bumblebees. Bursts of spikes resulted when a sucrose-activated GRN was inhibited by another GRN at a frequency of ∼22 Hz during the first 1 s of stimulation. Pharmacological blockade of gap junctions abolished bursting, indicating that bee GRNs have electrical synapses that produce a temporal pattern of spikes when one GRN is activated by a sugar ligand. Bursting permitted bee GRNs to maintain a high rate of spiking and to exhibit the slowest rate of adaptation of any insect species. Feeding bout duration correlated with coherent bursting; only sugar concentrations that produced bursting evoked the bumblebee's feeding reflex. Volume of solution imbibed was a direct function of time in contact with food. We propose that gap junctions among GRNs enable a sustained rate of GRN spiking that is necessary to drive continuous feeding by the bee proboscis.
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Affiliation(s)
- Ashwin Miriyala
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Sébastien Kessler
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - F Claire Rind
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK
| | - Geraldine A Wright
- Institute of Neuroscience, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
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248
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Felton MA, Yu AB, Boothe DL, Oie KS, Franaszczuk PJ. Resonance Analysis as a Tool for Characterizing Functional Division of Layer 5 Pyramidal Neurons. Front Comput Neurosci 2018; 12:29. [PMID: 29780316 PMCID: PMC5945999 DOI: 10.3389/fncom.2018.00029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 04/16/2018] [Indexed: 11/13/2022] Open
Abstract
Evidence suggests that layer 5 pyramidal neurons can be divided into functional zones with unique afferent connectivity and membrane characteristics that allow for post-synaptic integration of feedforward and feedback inputs. To assess the existence of these zones and their interaction, we characterized the resonance properties of a biophysically-realistic compartmental model of a neocortical layer 5 pyramidal neuron. Consistent with recently published theoretical and empirical findings, our model was configured to have a “hot zone” in distal apical dendrite and apical tuft where both high- and low-threshold Ca2+ ionic conductances had densities 1–2 orders of magnitude higher than anywhere else in the apical dendrite. We simulated injection of broad spectrum sinusoidal currents with linearly increasing frequency to calculate the input impedance of individual compartments, the transfer impedance between the soma and key compartments within the dendritic tree, and a dimensionless term we introduce called resonance quality. We show that input resonance analysis distinguished at least four distinct zones within the model based on properties of their frequency preferences: basal dendrite which displayed little resonance; soma/proximal apical dendrite which displayed resonance at 5–23 Hz, strongest at 5–10 Hz and hyperpolarized/resting membrane potentials; distal apical dendrite which displayed resonance at 8–19 Hz, strongest at 10 Hz and depolarized membrane potentials; and apical tuft which displayed a weak resonance largely between 8 and 10 Hz across a wide range of membrane potentials. Transfer resonance analysis revealed that changes in subthreshold electrical coupling were found to modulate the transfer resonant frequency of signals transmitted from distal apical dendrite and apical tuft to the soma, which would impact the frequencies that individual neurons are expected to respond to and reinforce. Furthermore, eliminating the hot zone was found to reduce amplification of resonance within the model, which contributes to reduced excitability when perisomatic and distal apical regions receive coincident stimulating current injections. These results indicate that the interactions between different functional zones should be considered in a more complete understanding of neuronal integration. Resonance analysis may therefore be a useful tool for assessing the integration of inputs across the entire neuronal membrane.
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Affiliation(s)
- Melvin A Felton
- Computational and Information Sciences Directorate, U. S. Army Research Laboratory, Adelphi, MD, United States
| | - Alfred B Yu
- Human Research and Engineering Directorate, U. S. Army Research Laboratory, Adelphi, MD, United States
| | - David L Boothe
- Human Research and Engineering Directorate, U. S. Army Research Laboratory, Adelphi, MD, United States
| | - Kelvin S Oie
- Human Research and Engineering Directorate, U. S. Army Research Laboratory, Adelphi, MD, United States
| | - Piotr J Franaszczuk
- Human Research and Engineering Directorate, U. S. Army Research Laboratory, Adelphi, MD, United States.,Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, United States
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249
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Antic SD, Hines M, Lytton WW. Embedded ensemble encoding hypothesis: The role of the "Prepared" cell. J Neurosci Res 2018; 96:1543-1559. [PMID: 29633330 DOI: 10.1002/jnr.24240] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Revised: 03/10/2018] [Accepted: 03/12/2018] [Indexed: 01/08/2023]
Abstract
We here reconsider current theories of neural ensembles in the context of recent discoveries about neuronal dendritic physiology. The key physiological observation is that the dendritic plateau potential produces sustained depolarization of the cell body (amplitude 10-20 mV, duration 200-500 ms). Our central hypothesis is that synaptically-evoked dendritic plateau potentials lead to a prepared state of a neuron that favors spike generation. The plateau both depolarizes the cell toward spike threshold, and provides faster response to inputs through a shortened membrane time constant. As a result, the speed of synaptic-to-action potential (AP) transfer is faster during the plateau phase. Our hypothesis relates the changes from "resting" to "depolarized" neuronal state to changes in ensemble dynamics and in network information flow. The plateau provides the Prepared state (sustained depolarization of the cell body) with a time window of 200-500 ms. During this time, a neuron can tune into ongoing network activity and synchronize spiking with other neurons to provide a coordinated Active state (robust firing of somatic APs), which would permit "binding" of signals through coordination of neural activity across a population. The transient Active ensemble of neurons is embedded in the longer-lasting Prepared ensemble of neurons. We hypothesize that "embedded ensemble encoding" may be an important organizing principle in networks of neurons.
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Affiliation(s)
- Srdjan D Antic
- Department of Neuroscience, Institute for Systems Genomics, Stem Cell Institute, UConn Health, Farmington, Connecticut
| | - Michael Hines
- Department of Neuroscience, Yale School of Medicine, New Haven, Connecticut
| | - William W Lytton
- Physiology and Pharmacology, Neurology, Biomedical Engineering, SUNY Downstate Medical Center, Brooklyn, New York.,Department of Neurology, Kings County Hospital, Brooklyn, New York
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250
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Usrey WM, Sherman SM. Corticofugal circuits: Communication lines from the cortex to the rest of the brain. J Comp Neurol 2018. [PMID: 29524229 DOI: 10.1002/cne.24423] [Citation(s) in RCA: 74] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Pyramidal cells in cortical Layers 5 and 6 are the only cells in the cerebral cortex with axons that leave the cortex to influence the thalamus. Layer 6 cells provide modulatory feedback input to all thalamic nuclei. Layer 5 cells provide driving input to higher-order thalamic nuclei and do not innervate first-order nuclei, which get their driving inputs from subcortical sources. Higher-order nuclei innervated by Layer 5 cells thus seem to be involved with cortico-thalamo-cortical communication. The Layer 5 axons branch to also target additional subcortical structures that mediate interactions with the external environment. These corticofugal pathways represent the only means by which the cortex influences the rest of the neuraxis and thus are essential for proper cortical function and species survival. Here we review current understanding of the corticofugal pathways from Layers 5 and 6 and speculate on their functional contributions to neural processing and behavior.
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Affiliation(s)
- W Martin Usrey
- Center for Neuroscience, University of California, Davis, Davis, California
| | - S Murray Sherman
- Department of Neurobiology, University of Chicago, Chicago, Illinois
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