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Information filtering by synchronous spikes in a neural population

JOURNAL OF COMPUTATIONAL NEUROSCIENCE 2013年第2期34卷 285-301页

作者： Sharafi, Nahal Benda, Jan Lindner, Benjamin Max Planck Inst Phys Komplexer Syst D-01187 Dresden Germany Bernstein Ctr Biozentrum Munchen Munich Germany Univ Tubingen Inst Neurobiol Tubingen Germany Humboldt Univ Inst Phys D-10099 Berlin Germany

Information about time-dependent sensory stimuli is encoded by the spike trains of neurons. Here we consider a population of uncoupled but noisy neurons (each subject to some intrinsic noise) that are driven by a common broadband signal. We ask specifically how much information is encoded in the synchronous activity of the population and how this information transfer is distributed with respect to frequency bands. In order to obtain some insight into the mechanism of information filtering effects found previously in the literature, we develop a mathematical framework to calculate the coherence of the synchronous output with the common stimulus for populations of simple neuron models. Within this frame, the synchronous activity is treated as the product of filtered versions of the spike trains of a subset of neurons. We compare our results for the simple cases of (1) a Poisson neuron with a rate modulation and (2) an LIF neuron with intrinsic white current noise and a current stimulus. For the Poisson neuron, formulas are particularly simple but show only a low-pass behavior of the coherence of synchronous activity. For the LIF model, in contrast, the coherence function of the synchronous activity shows a clear peak at high frequencies, comparable to recent experimental findings. We uncover the mechanism for this shift in the maximum of the coherence and discuss some biological implications of our findings.

关键词： Synchrony neural coding Stochastic integrate-and-fire neuron Noise

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PERIPHERAL MECHANISMS OF OLFACTORY DISCRIMINATION OF COMPLEX-MIXTURES BY THE SPINY LOBSTER - NO CELL-TYPES FOR MIXTURES BUT DIFFERENT CONTRIBUTIONS OF THE CELLS TO THE ACROSS NEURON PATTERNS

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BRAIN RESEARCH 1990年第2期513卷 225-236页

作者： GIRARDOT, MN DERBY, CD GEORGIA STATE UNIV DEPT BIOL ATLANTA GA 30303 USA

Toward understanding mechanisms of olfactory discrimination, we have examined the existence of cell types and the role of cells in the coding of odorant quality in the olfactory organ of the spiny lobster. The results consisted of responses of 30 antennular chemoreceptor cells to 8 behaviorally discriminable complex ***.4 natural extracts and 4 artificial mixtures, each at 3 concentrations. Multidimensional scaling and cluster analysis failed to identify unequivocal cell types, but rather suggested a continuum of cellular response profiles. The lack of cell types suggests that the code for the quality of natural odorants in this system is a population code. The distribution of cells along the response continuum was based on any of many features of their response profiles. The most effective stimulus (= best stimulus) and the least effective stimulus (= least stimulus), two features of the response profiles, could only partially explain the differences in response profiles of cells. Nonetheless, cells with different response profiles were shown to have different functions in odorant coding. Most cells contribute to some degree to the discrimination of any two stimuli, but a cell''s contribution to the discrimination of two stimuli is usually disproportionally robust when those two stimuli produce very different responses in that cell.

关键词： Chemoreception Olfaction Discrimination Lobster neural coding Cell type Mixture

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Rational thoughts in neural codes

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PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 2020年第47期117卷 29311-29320页

作者： Wu, Zhengwei Kwon, Minhae Daptardar, Saurabh Schrater, Paul Pitkow, Xaq Baylor Coll Med Dept Neurosci Houston TX 77030 USA Rice Univ Dept Elect & Comp Engn Houston TX 77030 USA Baylor Coll Med Ctr Neurosci & Artificial Intelligence Houston TX 77030 USA Google Atom Maps Geo Core Data Mountain View CA 94043 USA Univ Minnesota Dept Psychol Minneapolis MN 55455 USA Univ Minnesota Dept Comp Sci Minneapolis MN 55455 USA

Complex behaviors are often driven by an internal model, which integrates sensory information over time and facilitates long-term planning to reach subjective goals. A fundamental challenge in neuroscience is, How can we use behavior and neural activity to understand this internal model and its dynamic latent variables? Here we interpret behavioral data by assuming an agent behaves rationally-that is, it takes actions that optimize its subjective reward according to its understanding of the task and its relevant causal variables. We apply a method, inverse rational control (IRC), to learn an agent's internal model and reward function by maximizing the likelihood of its measured sensory observations and actions. This thereby extracts rational and interpretable thoughts of the agent from its behavior. We also provide a framework for interpreting encoding, recoding, and decoding of neural data in light of this rational model for behavior. When applied to behavioral and neural data from simulated agents performing suboptimally on a naturalistic foraging task, this method successfully recovers their internal model and reward function, as well as the Markovian computational dynamics within the neural manifold that represent the task. This work lays a foundation for discovering how the brain represents and computes with dynamic latent variables.

关键词： cognition neuroscience computation rational neural coding

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A neural model of retrospective attention in visual working memory

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COGNITIVE PSYCHOLOGY 2018年 100卷 43-52页

作者： Bays, Paul M. Taylor, Robert Univ Cambridge Dept Psychol Cambridge CB2 3EB England

An informative cue that directs attention to one of several items in working memory improves subsequent recall of that item. Here we examine the mechanism of this retro-cue effect using a model of short-term memory based on neural population coding. Our model describes recalled feature values as the output of an optimal decoding of spikes generated by a tuned population of neurons. This neural model provides a better account of human recall data than an influential model that assumes errors can be described as a mixture of normally distributed noise and random guesses. The retro-cue benefit is revealed to be consistent with a higher firing rate of the population encoding the cued versus uncued items, with no difference in tuning specificity. Additionally, a retro-cued item is less likely to be swapped with another item in memory, an effect that can also be explained by greater activity of the underlying population. These results provide a parsimonious account of the effects of retrospective attention on recall and demonstrate a principled method for investigating neural representations with behavioral tasks.

关键词： Working memory Retrospective cueing Attention neural coding Resource model

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Silences, spikes and bursts: Three-part knot of the neural code

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JOURNAL OF PHYSIOLOGY-LONDON 2023年第23期601卷 5165-5193页

作者： Friedenberger, Zachary Harkin, Emerson Toth, Katalin Naud, Richard Univ Ottawa Dept Cellular & Mol Med Brain & Mind Inst Ottawa ON Canada Univ Ottawa Ctr Neural Dynam & Artifical Intelligence Dept Phys Ottawa ON Canada Univ Ottawa 451 Smyth Rd Ottawa ON K1H 8M5 Canada

When a neuron breaks silence, it can emit action potentials in a number of patterns. Some responses are so sudden and intense that electrophysiologists felt the need to single them out, labelling action potentials emitted at a particularly high frequency with a metonym - bursts. Is there more to bursts than a figure of speech? After all, sudden bouts of high-frequency firing are expected to occur whenever inputs surge. The burst coding hypothesis advances that the neural code has three syllables: silences, spikes and bursts. We review evidence supporting this ternary code in terms of devoted mechanisms for burst generation, synaptic transmission and synaptic plasticity. We also review the learning and attention theories for which such a triad is *** Abstract figure legend The widely observed phenomenon of bursting is reviewed in terms of generation mechanisms, transmission mechanisms and function particularly in terms of plasticity and attention within the central nervous ***

关键词： attention learning long-term plasticity neural coding short-term plasticity

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Visual saliency and spike timing in the ventral visual pathway

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JOURNAL OF PHYSIOLOGY-PARIS 2003年第2-3期97卷 365-377页

作者： VanRullen, R CALTECH CNS Program Div Biol Pasadena CA 91125 USA

Visual saliency is a fundamental yet hard to define property of objects or locations in the visual world. In a context where objects and their representations compete to dominate our perception, saliency can be thought of as the "juice" that makes objects win the race. It is often assumed that saliency is extracted and represented in an explicit saliency map, which serves to determine the location of spatial attention at any given time. It is then by drawing attention to a salient object that it can be recognized or categorized. I argue against this classical view that Visual "bottom-up" saliency automatically recruits the attentional system prior to object recognition. A number Of Visual processing tasks are clearly performed too fast for such a costly strategy to be employed. Rather, visual attention could simply act by biasing a saliency-based object recognition system. Under natural conditions of stimulation, saliency can be represented implicitly throughout the ventral visual pathway, independent of any explicit saliency map. At any given level. the most activated cells of the neural population simply represent the most salient locations. The notion of saliency itself grows increasingly complex throughout the system, mostly based on luminance contrast until information reaches visual cortex, gradually incorporating information about features such as orientation or color in primary visual cortex and early extrastriate areas, and finally the identity and behavioral relevance of objects in temporal cortex and beyond. Under these conditions the object that dominates perception. i.e. the object yielding the strongest (or the first) selective neural response, is by definition the one whose features are most "salient"-without the need for any external saliency map. In addition, I Suggest that such an implicit representation of saliency can be best encoded in the relative times of the first spikes fired in a given neuronal population. In accordance with our subjective

关键词： visual saliency attention object recognition spike timing neural coding

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A NEW THEORY OF CEREBELLAR FUNCTION - MOVEMENT CONTROL THROUGH PHASE-INDEPENDENT RECOGNITION OF IDENTITIES BETWEEN TIME-BASED neural INFORMATIONAL SYMBOLS

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SYNAPSE 1990年第1期5卷 1-32页

作者： STREHLER, BL Molecular Biology University of Southern California Los Angles California 90089

A new theory designed to explain the functions of the cerebellum in th control of movement and the unique anatomy of that structures is presented. The heart of this proposed explanation is that the cerebellum generates increased numbers of outputs from particular Purkinje cells whenever the same pattern of pulses in time is presented both to its mossy fiber and its climbing fiber input systems. The postulated function of the unusual anatomy of the cerebellum is to permit it instantly to recognize and respond to identical patterns presented through these two channels regardless of the phase differences between these two signal sources, where phase differences are defined as differences in time of arrival of patterns of inputs from these two sources. The first means putatively used involves the summation of pulses comprising a given pattern of inputs simultaneously at many different Purkinje cells by virtue of the different speeds of conduction of the parallel fiber axons of granules cells. The second means is the addition of an input from the climbing fiber system that, together with the simultaneous parallel fiber inputs, leads to a discharge of particular Purkinje cells, which discharge temporarily increases the size of EPSP''s generated by the parallel fiber synapses involved in the cell''s discharge. This specific synaptic potentiation, in turn, makes it possible for the cell to respond by generating closely consecutive additional discharges provided that the same patterns of discharge are presented both to the climbing fiber system and the mossy fiber system. This happens because later pulses in identical patterns will arrive simultaneously at previously facilitated synapses via parallel fibers and at synapses of the climbing fibers, thereby causing additional spatial summations and discharges to occur. According to this explanation the patterns that are compared in the above manner are symbols (patterns of pulses) produced by sensors of current positions and sy

关键词： cerebellum neural coding pulse patterns time vectors dentate rubrum recticular nuclei feedback Parkinsoinsm Purkinje cells evolution of cerebellum

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Integrative activity of neural networks may code virtual spaces with internal representations

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NEUROSCIENCE LETTERS 2014年 581卷 80-84页

作者： Strelnikov, Kuzma CNRS CERCO Fac Med Rangueil UMR 5549 F-31052 Toulouse France

It was shown recently in neuroimaging that spatial differentiation of brain activity provides novel information about brain function. This confirms the integrative organisation of brain activity, but given present technical limitations of neuroimaging approaches, the exact role of integrative activity remains unclear. We trained a neural network to integrate information using random numbers' so as to imitate the "centre-periphery" pattern of brain activity in neuroimaging. Only the hierarchical organisation of the network permitted the learning of fast and reliable integration. We presented images to the trained network and, by spatial differentiation of the network activity, obtained virtual spaces with the presented images. Thus, our study established the necessity of the hierarchical organisation of neural networks for integration and demonstrated that the role of neural integration in the brain may be to create virtual spaces with internal representations of the objects. (C) 2014 Elsevier Ireland Ltd. All rights reserved.

关键词： Integrative neural coding Internal representations Brain activity

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Motor cortical control of movement speed with implications for brain-machine interface control

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JOURNAL OF NEUROPHYSIOLOGY 2014年第2期112卷 411-429页

作者： Golub, Matthew D. Yu, Byron M. Schwartz, Andrew B. Chase, Steven M. Carnegie Mellon Univ Dept Elect & Comp Engn Pittsburgh PA 15213 USA Carnegie Mellon Univ Ctr Neural Basis Cognit Pittsburgh PA 15213 USA Carnegie Mellon Univ Dept Biomed Engn Pittsburgh PA 15213 USA Univ Pittsburgh Dept Neurobiol Pittsburgh PA USA

Motor cortex plays a substantial role in driving movement, yet the details underlying this control remain unresolved. We analyzed the extent to which movement-related information could be extracted from single-trial motor cortical activity recorded while monkeys performed center-out reaching. Using information theoretic techniques, we found that single units carry relatively little speed-related information compared with direction-related information. This result is not mitigated at the population level: simultaneously recorded population activity predicted speed with significantly lower accuracy relative to direction predictions. Furthermore, a unit-dropping analysis revealed that speed accuracy would likely remain lower than direction accuracy, even given larger populations. These results suggest that the instantaneous details of single-trial movement speed are difficult to extract using commonly assumed coding schemes. This apparent paucity of speed information takes particular importance in the context of brain-machine interfaces (BMIs), which rely on extracting kinematic information from motor cortex. Previous studies have highlighted subjects' difficulties in holding a BMI cursor stable at targets. These studies, along with our finding of relatively little speed information in motor cortex, inspired a speed-dampening Kalman filter (SDKF) that automatically slows the cursor upon detecting changes in decoded movement direction. Effectively, SDKF enhances speed control by using prevalent directional signals, rather than requiring speed to be directly decoded from neural activity. SDKF improved success rates by a factor of 1.7 relative to a standard Kalman filter in a closed-loop BMI task requiring stable stops at targets. BMI systems enabling stable stops will be more effective and user-friendly when translated into clinical applications.

关键词： motor control neural coding brain-machine interface

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Circuit mechanisms revealed by spike-timing correlations in macaque area MT

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JOURNAL OF NEUROPHYSIOLOGY 2013年第3期109卷 851-866页

作者： Huang, Xin Lisberger, Stephen G. Univ Wisconsin Dept Neurosci Madison WI 53706 USA Duke Univ Dept Neurobiol Howard Hughes Med Inst Durham NC USA Univ Calif San Francisco Dept Physiol San Francisco CA USA

Huang X, Lisberger SG. Circuit mechanisms revealed by spike-timing correlations in macaque area MT. J Neurophysiol 109: 851-866, 2013. First published November 14, 2012;doi:10.1152/jn.00775.2012.-We recorded simultaneously from pairs of motion-sensitive neurons in the middle temporal cortex (MT) of macaque monkeys and used cross-correlations in the timing of spikes between neurons to gain insights into cortical circuitry. We characterized the time course and stimulus dependency of the cross-correlogram (CCG) for each pair of neurons and of the auto-correlogram (ACG) of the individual neurons. For some neuron pairs, the CCG showed negative flanks that emerged next to the central peak during stimulus-driven responses. Similar negative flanks appeared in the ACG of many neurons. Negative flanks were most prevalent and deepest when the neurons were driven to high rates by visual stimuli that moved in the neurons' preferred directions. The temporal development of the negative flanks in the CCG coincided with a parallel, modest reduction of the noise correlation between the spike counts of the neurons. Computational analysis of a model cortical circuit suggested that negative flanks in the CCG arise from the excitation-triggered mutual cross-inhibition between pairs of excitatory neurons. Intracortical recurrent inhibition and afterhyperpolarization caused by intrinsic outward currents, such as the calcium-activated potassium current of small conductance, can both contribute to the negative flanks in the ACG. In the model circuit, stronger intracortical inhibition helped to maintain the temporal precision between the spike trains of pairs of neurons and led to weaker noise correlations. Our results suggest a neural circuit architecture that can leverage activity-dependent intracortical inhibition to adaptively modulate both the synchrony of spike timing and the correlations in response variability.

关键词： neuron-neuron correlations synchrony neural coding visual cortex visual motion processing response variation Fano factor afterhyperpolarization

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