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Population-wide distributions of neural activity during perceptual decision-making

PROGRESS IN NEUROBIOLOGY 2013年 103卷 156-193页

作者： Wohrer, Adrien Humphries, Mark D. Machens, Christian K. Ecole Normale Super Grp Neural Theory INSERM U960 Dept Etud Cognit F-75005 Paris France Univ Manchester Fac Life Sci Manchester M60 1QD Lancs England Champalimaud Ctr Unknown Champalimaud Neurosci Programme P-1400038 Lisbon Portugal

Cortical activity involves large populations of neurons, even when it is limited to functionally coherent areas. Electrophysiological recordings, on the other hand, involve comparatively small neural ensembles, even when modern-day techniques are used. Here we review results which have started to fill the gap between these two scales of inquiry, by shedding light on the statistical distributions of activity in large populations of cells. We put our main focus on data recorded in awake animals that perform simple decision-making tasks and consider statistical distributions of activity throughout cortex, across sensory, associative, and motor areas. We transversally review the complexity of these distributions, from distributions of firing rates and metrics of spike-train structure, through distributions of tuning to stimuli or actions and of choice signals, and finally the dynamical evolution of neural population activity and the distributions of (pairwise) neural interactions. This approach reveals shared patterns of statistical organization across cortex, including: (i) long-tailed distributions of activity, where quasi-silence seems to be the rule for a majority of neurons;that are barely distinguishable between spontaneous and active states;(ii) distributions of tuning parameters for sensory (and motor) variables, which show an extensive extrapolation and fragmentation of their representations in the periphery;and (iii) population-wide dynamics that reveal rotations of internal representations overtime, whose traces can be found both in stimulus-driven and internally generated activity. We discuss how these insights are leading us away from the notion of discrete classes of cells, and are acting as powerful constraints on theories and models of cortical organization and population coding. (C) 2012 Elsevier Ltd. All rights reserved.

关键词： neural populations Cell-to-cell variability Perceptual decision-making Long-tailed distributions neural coding Population dynamics

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Regulation of information passing by synaptic transmission: A short review

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BRAIN RESEARCH 2008年 1225卷 26-38页

作者： Di Maio, Vito CNR Ist Cibernet E Caianiello I-80078 Pozzuoli NA Italy

The largest part of information passed among neurons in the brain occurs by the means of chemical synapses connecting the axons of presynaptic neurons to the dendritic tree of the postsynaptic ones. In the present paper, the most relevant open problems related to the mechanisms of control of the information passing among neurons by synaptic transmission will be shortly reviewed. The "cross talking" between synapses, their mutual interactions and the control of the information flow between different areas of the dendritic tree will be also considered. The threshold mechanism based on the "reversal potential" will be considered for its role in the control of information transfer among neurons and also for its contribution to the information flow among different areas of the dendritic tree and to the computational ability of the single neuron. The concept of "competition for plasticity" will be proposed as a mechanism of competition based on the synaptic activation time. (C) 2008 Elsevier B.V. All rights reserved.

关键词： synaptic interaction synaptic integration neural coding neuronal modelling neural information processing synaptic competition

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Computational themes of peripheral processing in the auditory pathway of insects

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JOURNAL OF COMPARATIVE PHYSIOLOGY A-NEUROETHOLOGY SENSORY neural AND BEHAVIORAL PHYSIOLOGY 2015年第1期201卷 39-50页

作者： Hildebrandt, K. Jannis Benda, Jan Hennig, R. Matthias Carl von Ossietzky Univ Oldenburg Dept Neurosci Cluster Excellence Hearing4all D-26111 Oldenburg Germany Univ Tubingen Inst Neurobiol D-72076 Tubingen Germany Humboldt Univ Dept Biol D-10115 Berlin Germany

Hearing in insects serves to gain information in the context of mate finding, predator avoidance or host localization. For these goals, the auditory pathways of insects represent the computational substrate for object recognition and localization. Before these higher level computations can be executed in more central parts of the nervous system, the signals need to be preprocessed in the auditory periphery. Here, we review peripheral preprocessing along four computational themes rather than discussing specific physiological mechanisms: (1) control of sensitivity by adaptation, (2) recoding of amplitude modulations of an acoustic signal into a labeled-line code (3) frequency processing and (4) conditioning for binaural processing. Along these lines, we review evidence for canonical computations carried out in the peripheral auditory pathway and show that despite the vast diversity of insect hearing, signal processing is governed by common computational motifs and principles.

关键词： Spike frequency adaptation neural coding Sensory processing

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Fine Spike Timing in Hippocampal-Prefrontal Ensembles Predicts Poor Encoding and Underlies Behavioral Performance in Healthy and Malformed Brains

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CEREBRAL CORTEX 2021年第1期31卷 147-158页

作者： Hernan, Amanda E. Mahoney, J. Matthew Curry, Willie Mawe, Seamus Scott, Rod C. Univ Vermont Dept Neurol Sci Larner Coll Med Burlington VT 05401 USA Univ Vermont Dept Comp Sci Burlington VT 05401 USA UCL Inst Child Hlth Neurosci Unit London WC1N 1EH England

Spatial working memory (SWM) is a central cognitive process during which the hippocampus and prefrontal cortex (PFC) encode and maintain spatial information for subsequent decision-making. This occurs in the context of ongoing computations relating to spatial position, recall of long-term memory, attention, among many others. To establish how intermittently presented information is integrated with ongoing computations we recorded single units, simultaneously in hippocampus and PFC, in control rats and those with a brain malformation during performance of an SWM task. Neurons that encode intermittent task parameters are also well modulated in time and incorporated into a functional network across regions. Neurons from animals with cortical malformation are poorly modulated in time, less likely to encode task parameters, and less likely to be integrated into a functional network. Our results implicate a model in which ongoing oscillatory coordination among neurons in the hippocampal-PFC network describes a functional network that is poised to receive sensory inputs that are then integrated and multiplexed as working memory. The background temporal modulation is systematically altered in disease, but the relationship between these dynamics and behaviorally relevant firing is maintained, thereby providing potential targets for stimulation-based therapies.

关键词： cortical malformations executive function hippocampus neural coding prefrontal cortex

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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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Information filtering by synchronous spikes in a neural population

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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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A neural model of retrospective attention in visual working memory

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COGNITIVE PSYCHOLOGY 2018年第0期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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On words and brains: linking psycholinguistics with neural dynamics in speech production

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LANGUAGE COGNITION AND NEUROSCIENCE 2016年第4期31卷 524-535页

作者： Strijkers, Kristof Costa, Albert Aix Marseille Univ CNRS UMR 7309 Lab Parole & Language Aix En Provence France Pompeu Fabra Univ Dept Technol Ctr Brain & Cognit Barcelona Spain ICREA Barcelona Spain

Obtaining a neurophysiology of language production is a complex endeavour which, at present, is in its "infancy". It will require the integration of long-standing psycholinguistic models and phenomena with the anatomical and dynamical constraints of neural coding. In our target article [Strijkers, K., & Costa, A. (2016). The cortical dynamics of speaking: Present shortcomings and future avenues. Language, Cognition and Neuroscience, 1-20. doi: 10.1080/23273798.2015. 1120878;henceforth S&C], we hypothesized that one promising way of doing so is by perceiving words as cortical assemblies in a proactive brain. Conceptualizing word production as such means that some of the traditional assumptions underlying psycholinguistic models will need to be re-assessed (or at least extended) in light of this novel perspective. However, it does not mean that it is the only conceivable way to integrate language and the brain nor that neuroscience should be prioritized over psycholinguistics. Rather, its importance lies in making the linking hypothesizes between linguistic function and neural code explicit so that we can empirically test the integration of both domains. Likely, some of the linking hypotheses proposed in S&C may be proven wrong, but more importantly, others may prove to be an advance in the right direction towards a mechanistic framework of the cortical dynamics of speaking.

关键词： Speech production psycholinguistics neural coding

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Serotonin selectively enhances perception and sensory neural responses to stimuli generated by same-sex conspecifics

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PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 2013年第48期110卷 19609-19614页

作者： Deemyad, Tara Metzen, Michael G. Pan, Yingzhou Chacron, Maurice J. McGill Univ Dept Physiol Montreal PQ H3G 1Y6 Canada McGill Univ Dept Phys Montreal PQ H3G 1Y6 Canada

Centrifugal serotonergic fibers innervating sensory brain areas are seen ubiquitously across systems and species but their function remains unclear. Here we examined the functional role of serotonergic innervation onto electrosensory neurons in weakly electric fish by eliciting endogenous release through electrical stimulation as well as exogenous focal application of serotonin in the vicinity of the cell being recorded from. Both approaches showed that the function of serotonergic input onto electrosensory pyramidal neurons is to render them more excitable by reducing the spike afterhyperpolarization amplitude and thereby promoting burst firing. Further, serotonergic input selectively improved neuronal responses to stimuli that occur during interactions between same-sex conspecifics but not to stimuli associated with either prey or that occur during interactions between opposite-sex conspecifics. Finally, we tested whether serotonin-mediated enhanced pyramidal neuron responses to stimuli associated with same-sex conspecifics actually increase perception by the animal. Our behavioral experiments show that exogenous injection and endogenous release of serotonin both increase the magnitude of behavioral responses to stimuli associated with same-sex conspecifics as well as simultaneously decrease aggressive behaviors. Thus, our data indicate that the serotonergic system inhibits aggressive behavior toward same-sex conspecifics, while at the same time increasing perception of stimuli associated with these individuals. This function is likely to be conserved across systems and species.

关键词： neuromodulation neuroethology excitability neural coding

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Photoreceptive retinal ganglion cells control the information rate of the optic nerve

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PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 2018年第50期115卷 E11817-E11826页

作者： Milosavljevic, Nina Storchi, Riccardo Eleftheriou, Cyril G. Colins, Andrea Petersen, Rasmus S. Lucas, Robert J. Univ Manchester Fac Biol Med & Hlth Manchester M13 9PT Lancs England Ist Italiano Tecnol Ctr Synapt Neurosci & Technol I-16132 Genoa Italy

Information transfer in the brain relies upon energetically expensive spiking activity of neurons. Rates of information flow should therefore be carefully optimized, but mechanisms to control this parameter are poorly understood. We address this deficit in the visual system, where ambient light (irradiance) is predictive of the amount of information reaching the eye and ask whether a neural measure of irradiance can therefore be used to proactively control information flow along the optic nerve. We first show that firing rates for the retina's output neurons [retinal ganglion cells (RGCs)] scale with irradiance and are positively correlated with rates of information and the gain of visual responses. Irradiance modulates firing in the absence of any other visual signal confirming that this is a genuine response to changing ambient light. Irradiance-driven changes in firing are observed across the population of RGCs (including in both ON and OFF units) but are disrupted in mice lacking melanopsin [the photopigment of irradiance-coding intrinsically photosensitive RGCs (ipRGCs)] and can be induced under steady light exposure by chemogenetic activation of ipRGCs. Artificially elevating firing by chemogenetic excitation of ipRGCs is sufficient to increase information flow by increasing the gain of visual responses, indicating that enhanced firing is a cause of increased information transfer at higher irradiance. Our results establish a retinal circuitry driving changes in RGC firing as an active response to alterations in ambient light to adjust the amount of visual information transmitted to the brain.

关键词： neural coding information melanopsin ipRGC retina

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