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White noise analysis for the correlation-type elementary motion detectors with half-wave rectifiers

neural NETWORKS 2018年 102卷 96-106页

作者： Ikeda, Hideaki Aonishi, Toru Tokyo Inst Technol Grad Sch Interdisciplinary Sci & Engn Midori Ku Nagatsuda Cho 4259-G5-17 Yokohama Kanagawa 2268502 Japan Tokyo Inst Technol Sch Comp Midori Ku Nagatsuda Cho 4259-G5-17 Yokohama Kanagawa 2268502 Japan

The motion detection mechanism of insects has been attracted attention of many researchers. Several motion-detection models have been proposed on the basis of insect visual system studies. Here, we examine two models, the Hassenstein-Reichardt (HR) model and the two-detector (2D) model. We analytically obtain the mean and variance of the stationary responses of the HR and the 2D models to white noise, and we derive the signal-to-fluctuation-noise ratio (SFNR) to evaluate encoding abilities of the two models. Especially when analyzing the 2D model, we calculate higher-order cumulants of a rectified Gaussian. The results show that the 2D model robustly works almost as well as the HR model in several sets of parameters estimated on the basis of experimental data. (c) 2018 Elsevier Ltd. All rights reserved.

关键词： Motion detection neural coding White-noise analysis Hassenstein-Reichardt model Two-detector model

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How Far can neural Correlations Reduce Uncertainty? Comparison of Information Transmission Rates for Markov and Bernoulli Processes

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INTERNATIONAL JOURNAL OF neural SYSTEMS 2019年第8期29卷 1950003页

作者： Pregowska, Agnieszka Kaplan, Ehud Szczepanski, Janusz Polish Acad Sci Inst Fundamental Technol Res Ul Pawinskiego 5B PL-02106 Warsaw Poland Icahn Sch Med Mt Sinai One Gustave Levy Pl New York NY 10029 USA Charles Univ Prague Fac Sci Dept Philosophy & Hist Sci Albertov 6 Prague 12843 2 Czech Republic Natl Inst Mental Hlth Topolova 748 Klecany 25067 Czech Republic

The nature of neural codes is central to neuroscience. Do neurons encode information through relatively slow changes in the firing rates of individual spikes (rate code) or by the precise timing of every spike (temporal code)? Here we compare the loss of information due to correlations for these two possible neural codes. The essence of Shannon's definition of information is to combine information with uncertainty: the higher the uncertainty of a given event, the more information is conveyed by that event. Correlations can reduce uncertainty or the amount of information, but by how much? In this paper we address this question by a direct comparison of the information per symbol conveyed by the words coming from a binary Markov source (temporal code) with the information per symbol coming from the corresponding Bernoulli source (uncorrelated, rate code). In a previous paper we found that a crucial role in the relation between information transmission rates (ITRs) and firing rates is played by a parameter s, which is the sum of transition probabilities from the no-spike state to the spike state and vice versa. We found that in this case too a crucial role is played by the same parameter s. We calculated the maximal and minimal bounds of the quotient of ITRs for these sources. Next, making use of the entropy grouping axiom, we determined the loss of information in a Markov source compared with the information in the corresponding Bernoulli source for a given word length. Our results show that in the case of correlated signals the loss of information is relatively small, and thus temporal codes, which are more energetically efficient, can replace rate codes effectively. These results were confirmed by experiments.

关键词： Shannon information theory information source information transmission rate firing rate neural coding

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Nonoscillatory Phase coding and Synchronization in the Bat Hippocampal Formation

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CELL 2018年第4期175卷 1119-+页

作者： Eliav, Tamir Geva-Sagiv, Maya Yartsev, Michael M. Finkelstein, Arseny Rubin, Alon Las, Liora Ulanovsky, Nachum Weizmann Inst Sci Dept Neurobiol IL-76100 Rehovot Israel Hebrew Univ Jerusalem ELSC Ctr Brain Sci IL-91904 Jerusalem Israel Univ Calif Los Angeles Dept Neurosurg Los Angeles CA 90095 USA Tel Aviv Univ Sagol Sch Neurosci IL-69978 Tel Aviv Israel Tel Aviv Univ Sackler Sch Med IL-69978 Tel Aviv Israel Univ Calif Berkeley Dept Bioengn Berkeley CA 94720 USA Univ Calif Berkeley Helen Wills Neurosci Inst Berkeley CA 94720 USA Howard Hughes Med Inst Janelia Res Campus Ashburn VA 20147 USA

Hippocampal theta oscillations were proposed to be important for multiple functions, including memory and temporal coding of position. However, previous findings from bats have questioned these proposals by reporting absence of theta rhythmicity in bat hippocampal formation. Does this mean that temporal coding is unique to rodent hippocampus and does not generalize to other species? Here, we report that, surprisingly, bat hippocampal neurons do exhibit temporal coding similar to rodents, albeit without any continuous oscillations at the 1-20 Hz range. Bat neurons exhibited very strong locking to the non-rhythmic fluctuations of the field potential, such that neurons were synchronized together despite the absence of oscillations. Further, some neurons exhibited "phase precession'' and phase coding of the bat's position-with spike phases shifting earlier as the animal moved through the place field. This demonstrates an unexpected type of neural coding in the mammalian brain-nonoscillatory phase coding-and highlights the importance of synchrony and temporal coding for hippocampal function across species.

关键词： hippocampus entorhinal cortex place cells grid cells interneurons theta oscillation phase precession neural coding bats comparative neurobiology

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Slip-Based coding of Local Shape and Texture in Mouse S1

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NEURON 2018年第2期97卷 418-+页

作者： Isett, Brian R. Feasel, Sierra H. Lane, Monet A. Feldman, Daniel E. Univ Calif Berkeley Dept Mol & Cell Biol Berkeley CA 94720 USA Univ Calif Berkeley Helen Wills Neurosci Inst Berkeley CA 94720 USA

Tactile objects have both local geometry (shape) and broader macroscopic texture, but how these different spatial scales are simultaneously encoded during active touch is unknown. In the whisker system, we tested for a shared code based on localized whisker micromotions (stick-slips) and slip-evoked spikes. We trained mice to discriminate smooth from rough surfaces, including ridged gratings and sandpaper. Whisker slips locked to ridges and evoked temporally precise spikes (<10 ms jitter) in somatosensory cortex (S1) that could resolve ridges with similar to 1 mm accuracy. Slip-sensitive neurons also encoded touch and texture. On rough surfaces, both slip-evoked spikes and an additional non-slip signal elevated mean firing rate, allowing accurate rough-smooth texture decoding from population firing rate. Eighteen percent of neurons were selective among rough surfaces. Thus, slips elicit spatially and temporally precise spiking in S1 that simultaneously encodes local shape (ridges) and is integrated into a macroscopic firing rate code for roughness.

关键词： neural coding barrel cortex texture shape spatial tuning active sensation virtual foraging stick-slip multiplexed code S1 cortex

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Dynamic population coding and its relationship to working memory

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JOURNAL OF NEUROPHYSIOLOGY 2018年第5期120卷 2260-2268页

作者： Meyers, Ethan M. MIT Ctr Brains Minds & Machines 77 Massachusetts Ave Cambridge MA 02139 USA Hampshire Coll Sch Cognit Sci Amherst MA 01002 USA

For over 45 years, neuroscientists have conducted experiments aimed at understanding the neural basis of working memory. Early results examining individual neurons highlighted that information is stored in working memory in persistent sustained activity where neurons maintained elevated firing rates over extended periods of time. However, more recent work has emphasized that information is often stored in working memory in dynamic population codes, where different neurons contain information at different periods in time. In this paper, I review findings that show that both sustained activity as well as dynamic codes are present in the prefrontal cortex and other regions during memory delay periods. I also review work showing that dynamic codes are capable of supporting working memory and that such dynamic codes could easily be "readout" by downstream regions. Finally, I discuss why dynamic codes could be useful for enabling animals to solve tasks that involve working memory. Although additional work is still needed to know definitively whether dynamic coding is critical for working memory, the findings reviewed here give insight into how different codes could contribute to working memory, which should be useful for guiding future research.

关键词： dynamic coding neural coding persistent activity population decoding working memory

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Contrast coding in the primary visual cortex depends on temporal contexts

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EUROPEAN JOURNAL OF NEUROSCIENCE 2018年第8期47卷 947-958页

作者： Dai, Ji Wang, Yi Chinese Acad Sci Inst Biophys State Key Lab Brain & Cognit Sci Beijing 100101 Peoples R China Chinese Acad Sci Shenzhen Inst Adv Technol Shenzhen Key Lab Neuropsychiat Modulat Shenzhen 518055 Peoples R China Chinese Acad Sci Shenzhen Inst Adv Technol CAS Ctr Excellence Brain Sci & Intelligence Techn Collaborat Innovat Ctr Brain SciBrain Cognit & B Shenzhen 518055 Peoples R China Univ Chinese Acad Sci Beijing 100101 Peoples R China

Contrast response function in the primary visual cortex (V1) has long been described as following a sigmoid curve. However, this is mainly based on measuring neural responses to drifting contrast grating in a stable stimulation, a model that does not consider the effects of motion or length of stimulus presentation. During natural viewing, the visual system can obtain sufficient information for identifying the shapes defined by contrast from a single glance;acquiring greater knowledge of the neuronal response properties to contrast in such a short timescale is necessary to understand the underlying mechanisms. We investigated responses of cat V1 neurons to contrast presented by static grating for 40ms without pause compared to drifting grating presented continuously for 2000ms. The neuronal response to transiently presented contrast could be well described by a linear function. Further examination of the effects of motion and presentation duration on contrast responses demonstrated that motion increased response sensitivity in the low-contrast range, while brief presentation increased response sensitivity in the high-contrast range. Motion and prolonged presentation (adaptation) together resulted in an asymptotic sigmoid curve with a saturation response in the high-contrast range. These results suggest that motion mainly enhance the neural response sensitivity to low-contrast objects, while short and rapid presentation mainly enhance the neural sensitivity to high-contrast stimulus. Our findings indicate that multiple factors influence the properties of contrast response functions, suggesting that V1 neuron contrast coding is flexible and depends on the temporal contexts.

关键词： contrast response motion neural coding stimulus duration striate cortex

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INFORMATION PROCESSING ACROSS BEHAVIORAL STATES: MODES OF OPERATION AND POPULATION DYNAMICS IN RODENT SENSORY CORTEX

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NEUROSCIENCE 2018年第0期368卷 214-228页

作者： Sabri, Mohammad Mahdi Arabzadeh, Ehsan Australian Natl Univ Eccles Inst Neurosci John Curtin Sch Med Res Canberra ACT Australia Inst Res Fundamental Sci IPM Sch Cognit Sci Tehran Iran Australian Natl Univ Node Ctr Excellence Integrat Brain Funct Australian Res Council Canberra ACT Australia

Animals live in a complex and changing environment with various degrees of behavioral demands. In rodents, the behavioral states can change from sleep and quiet wakefulness to active exploration of the environment which is often manifested by whisking and locomotion. Efficient information processing is more important in some of these behavioral states such as during episodes of sensory decision-making, and specific cortical areas are expected to receive priority of processing depending on the behavioral context. It is therefore not surprising that the behavioral state affects the responsiveness of individual cortical neurons and the dynamics of neuronal population activity. Here, we review the circuit mechanisms that determine the operating mode of the sensory cortex. We explore state modulations across multiple sensory modalities, but maintain a focus on whisker-mediated behaviors, the processing of information in the vibrissal somatosensory cortex and its transfer to higher order areas. Finally, we suggest a rodent sensory prioritization paradigm to further probe the link between behavioral state, neuronal population dynamics and coding efficiency. This article is part of a Special Issue entitled: Barrel Cortex. (C) 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

关键词： behavioral state cortical circuits neural coding barrel cortex attention sensory prioritization

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ORGANIZATION OF ORIENTATION-SPECIFIC WHISKER DEFLECTION RESPONSES IN LAYER 2/3 OF MOUSE SOMATOSENSORY CORTEX

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NEUROSCIENCE 2018年第0期368卷 46-56页

作者： Kwon, Sung Eun Tsytsarev, Vassiliy Erzurumlu, Reha S. O'Connor, Daniel H. Johns Hopkins Univ Kavli Neurosci Discovery Inst Brain Sci Inst Solomon H Snyder Dept NeurosciSch Med Baltimore MD USA Univ Maryland Sch Med Dept Anat & Neurobiol Baltimore MD 21201 USA

The rodent whisker-barrel system is characterized by its patterned somatotopic mapping between the sensory periphery and multiple regions of the brain. While somatotopy in the whisker system is established, we know far less about how preferences for stimulus orientation or other features are organized. Mouse somatosensation is an increasingly popular model for circuit-based dissection of perceptual decision making and learning, yet our understanding of how stimulus feature representations are organized in the cortex is incomplete. Here, we used in vivo two-photon calcium imaging to monitor activity of populations of layer (L) 2/3 neurons in the mouse primary somatosensory cortex during deflections of a single whisker in two orthogonal orientations (azimuthal or elevational). We split the population response to whisker deflections into an orientation-specific component and a non-specific component that reflected overall excitability in response to deflection of a single whisker. Orientation-specific responses were organized in a locally heterogeneous and spatially distributed manner. Correlations in the stimulus-independent trial-to-trial variability of pairs of neurons were higher among neurons that preferred the same orientation. These correlations depended on similarity in both orientation-specific and non-specific components of responses to single-whisker deflections. Our results shed light on L2/3 organization in mouse somatosensory cortex, and lay a foundation for dissecting circuit mechanisms of perceptual learning and decision-making during orientation discrimination tasks. This article is part of a Special Issue entitled: Barrel Cortex. (C) 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

关键词： rodent whisker system neural coding barrel cortex orientation tuning two-photon calcium imaging noise correlation

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Precise Synaptic Balance in the Zebrafish Homolog of Olfactory Cortex

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NEURON 2018年第3期100卷 669-+页

作者： Rupprecht, Peter Friedrich, Rainer W. Friedrich Miescher Inst Biomed Res Maulbeerstr 66 CH-4058 Basel Switzerland Univ Basel Fac Nat Sci CH-4003 Basel Switzerland

Neuronal computations critically depend on the connectivity rules that govern the convergence of excitatory and inhibitory synaptic signals onto individual neurons. To examine the functional synaptic organization of a distributed memory network, we performed voltage clamp recordings in telencephalic area Dp of adult zebrafish, the homolog of olfactory cortex. In neurons of posterior Dp, odor stimulation evoked large, recurrent excitatory and inhibitory inputs that established a transient state of high conductance and synaptic balance. Excitation and inhibition in individual neurons were co-tuned to different odors and correlated on slow and fast time-scales. This precise synaptic balance implies specific connectivity among Dp neurons, despite the absence of an obvious topography. Precise synaptic balance stabilizes activity patterns in different directions of coding space and in time while preserving high bandwidth. The coordinated connectivity of excitatory and inhibitory subnetworks in Dp therefore supports fast recurrent memory operations.

关键词： olfactory cortex zebrafish balanced state voltage clamp neural coding neural computation piriform cortex

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Cortical coding of Auditory Features

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ANNUAL REVIEW OF NEUROSCIENCE, VOL 41 2018年第1期41卷 527-552页

作者： Wang, Xiaoqin Johns Hopkins Univ Dept Biomed Engn Lab Auditory Neurophysiol Baltimore MD 21205 USA Tsinghua Univ Tsinghua Lab Brain & Intelligence THBI Beijing 100084 Peoples R China Tsinghua Univ Dept Biomed Engn Beijing 100084 Peoples R China

How the cerebral cortex encodes auditory features of biologically important sounds, including speech and music, is one of the most important questions in auditory neuroscience. The pursuit to understand related neural coding mechanisms in the mammalian auditory cortex can be traced back several decades to the early exploration of the cerebral cortex. Significant progress in this field has been made in the past two decades with new technical and conceptual advances. This article reviews the progress and challenges in this area of research.

关键词： auditory cortex speech hearing pitch music neural coding

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