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NEUROCOMPUTING 2001年 38卷 1181-1184页

作者： Del Prete, V Steinberg, O Treves, A Vaadia, E SISSA Cognit Neurosci I-34014 Trieste Italy Hebrew Univ Jerusalem Hadassah Med Sch IL-91010 Jerusalem Israel Hebrew Univ Jerusalem Ctr Neural Computat IL-91010 Jerusalem Israel

A previous study revealed that neuronal activity in primary motor cortex (MI) and supplementary motor area (SMA) of the monkey depends both on which arm(s) moved and on the direction of movement. At the level of single cells, no differences were found between the areas in the information conveyed about each correlate. We constructed pseudosimultaneous response vectors and applied a decoding algorithm to quantify differences at a population level. We found that, on average, samples of 20 MI units carried less information about both movement type and direction than SMA units in a time window of 500 ms across the movement onset;a more detailed temporal analysis has revealed that SMA precedes M1 in motor planning and execution and that along the trial M1 cells carry as much information about direction as SMA cells. (C) 2001 Elsevier Science B.V. All rights reserved.

关键词： neural coding mote cortex information theory

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PERIPHERAL neural BASIS OF TACTILE SENSATIONS IN MAN .2. CHARACTERISTICS OF HUMAN MECHANORECEPTORS IN THE HAIRY SKIN AND CORRELATIONS OF THEIR ACTIVITY WITH TACTILE SENSATIONS

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BRAIN RESEARCH 1981年第1期219卷 13-27页

作者： JARVILEHTO, T HAMALAINEN, H SOININEN, K Department of Psychology Experimental Laboratories Ritarikatu 5 SF-00170 Helsinki 17 Finland

Properties of the human mechanoreceptors in the hairy skin of the back of the hand were studied by microelectrode measurements from the radial nerve. Correlations of unit activity with sensations elicited by tactile pulses (single cycle sinusoids of 20, 60 and 150 Hz) were examined with simultaneous measurements of unit activity and sensation thresholds and magnitude. A total of 264 mechanoreceptive units was identified. Of all units, 66% were classified as slowly adapting (SA) and 34% as rapidly adapting (RA) units. Mechanical thresholds of the units as well as simultaneously measured sensation thresholds decreased with increasing frequency of the pulse. The thresholds of several SA units were identical with the subjective thresholds. The responses of the units to supraliminal pulses consisted maximally of 7 impulses. Most SAI and RA units were able to code to some extent the stimulus amplitude on the basis of number of impulses, but only RA units had stimulus-response functions indicating velocity coding. Comparisons of the estimates of sensation magnitude with the number of impulses in the response indicated that the estimate may be based mainly on activity in a population of RA units. The comparison of the present results with earlier reports on properties of receptors in the glabrous skin of the human hand indicates that there are some differences between the characteristics of receptors in the hairy and glabrous skin. Human receptors in the hairy skin do not seem to differ from the corresponding receptors in the animals.

关键词： skin mechanoreceptors touch man neural coding

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SPECTRAL CHARACTERISTICS OF THE RESPONSES OF PRIMARY AUDITORY-NERVE FIBERS TO AMPLITUDE-MODULATED SIGNALS

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HEARING RESEARCH 1989年第1-2期39卷 143-157页

作者： KHANNA, SM TEICH, MC COLUMBIA UNIV DEPT ENGN NEW YORK NY 10027 USA

The spectral responses of cat single primary auditory nerve fibers to sinusoidal amplitude-modulated (9AM) and dobule-sideband (DSB) acoustic signals applied to the ear were examined. DSB is an amplitude-modulated signal with a suppressed carrier. Period histograms were compiled from the neural spike-train data, and the frequency spectrum was determined by Fourier transforming these histograms. For DSB signals, spectral components were found to be present at the frequencies of the stimulus as well as at certain combinations frequencies. For AM signals, several clusters of spectral components were present. The lowest-frequency cluster consisted of components at DC, at the modulation frequency, and at its harmonics. A higher frequency cluster occurs around a component with the frequency of the carrier. The components of cluster are separated from the carrier by the modulation frequency and its harmonics. Yet higher-frequency clusters appear around multiples of the carrier frequency with components at frequencies separated from these multiples by the modulation frequency and its harmonics. The magnitudes of these spectral components were determined for carrier frequencies located below, at, and above the characteristic frequency of the units, and for different stimulus levels, modulation frequencies, and modulation depths. The low-frequency components present in the neural spike train appear to be the results of demodulation taking place in the inner ear. The demodulated components are strong and are present over a wide range of sound levels, carrier frequencies, modulation frequencies, and nerve-fiber characteristics. This demodulation may be significant for speech recognition.

关键词： Auditory-nerve fiber Frequency modulation neural coding Spectral characteristics

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Comparing the Prefrontal Cortex of Rats and Primates: Insights from Electrophysiology

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NEUROTOXICITY RESEARCH 2008年第2-3期14卷 249-262页

作者： Seamans, Jeremy K. Lapish, Christopher C. Durstewitz, Daniel Univ British Columbia Dept Psychiat Vancouver BC V6T 2B5 Canada Univ British Columbia Brain Res Ctr Vancouver BC V6T 2B5 Canada Univ Plymouth Ctr Theoret & Computat Neurosci Plymouth PL4 8AA Devon England

There is a long-standing debate about whether rats have what could be considered a prefrontal cortex (PFC) and, if they do, what its primate homologue is. Anatomical evidence supports the view that the rat medial PFC is related to both the primate anterior cingulate cortex (ACC) and the dorsolateral PFC. Functionally the primate and human ACC are believed to be involved in the monitoring of actions and outcomes to guide decisions especially in challenging situations where cognitive conflict and errors arise. In contrast, the dorsolateral PFC is responsible for the maintenance and manipulation of goal-related items in memory in the service of planning, problem solving, and predicting forthcoming events. Recent multiple single-unit recording studies in rats have reported strong correlates of motor planning, movement and reward anticipation analogous to what has been observed in the primate ACC. There is also emerging evidence that rats may partly encode information over delays using body posture or variations in running path as embodied strategies, and that these are the aspects tracked by medial PFC neurons. The primate PFC may have elaborated on these rudimentary functions by carrying them over to more abstract levels of mental representation, more independent from somatic or other external mnemonic cues, and allowing manipulation of mental contents outside specific task contexts. Therefore, from an electrophysiological and computational perspective, the rat medial PFC seems to combine elements of the primate ACC and dorsolateral PFC at a rudimentary level. In primates, these functions may have formed the building blocks required for abstract rule encoding during the expansion of the cortex dorsolaterally.

关键词： Decision making Working memory Cell assemblies neural coding Higher cognition

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Modulation of sensory information processing by a neuroglobin in Caenorhabditis elegans

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PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA 2017年第23期114卷 E4658-E4665页

作者： Oda, Shigekazu Toyoshima, Yu de Bono, Mario MRC Mol Biol Lab Div Cell Biol Cambridge CB2 0QH England Univ Tokyo Grad Sch Sci Dept Biol Sci Tokyo 1130033 Japan Natl Inst Nat Sci Okazaki Inst Integrat Biosci Okazaki Aichi 4448787 Japan

Sensory receptor neurons match their dynamic range to ecologically relevant stimulus intensities. How this tuning is achieved is poorly understood in most receptors. The roundworm Caenorhabditis elegans avoids 21% O-2 and hypoxia and prefers intermediate O-2 concentrations. We show how this O-2 preference is sculpted by the antagonistic action of a neuroglobin and an O-2-binding soluble guanylate cyclase. These putative molecular O-2 sensors confer a sigmoidal O-2 response curve in the URX neurons that has highest slope between 15 and 19% O-2 and approaches saturation when O-2 reaches 21%. In the absence of the neuroglobin, the response curve is shifted to lower O-2 values and approaches saturation at 14% O-2. In behavioral terms, neuroglobin signaling broadens the O-2 preference of Caenorhabditis elegans while maintaining avoidance of 21% O-2. A computational model of aerotaxis suggests the relationship between GLB-5-modulated URX responses and reversal behavior is sufficient to broaden O-2 preference. In summary, we show that a neuroglobin can shift neural information coding leading to altered behavior. Antagonistically acting molecular sensors may represent a common mechanism to sharpen tuning of sensory neurons.

关键词： sensory neuron tuning neural coding oxygen sensing neuroglobin computational model

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Information transmission and detection thresholds in the vestibular nuclei: single neurons vs. population encoding

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JOURNAL OF NEUROPHYSIOLOGY 2011年第4期105卷 1798-1814页

作者： Massot, Corentin Chacron, Maurice J. Cullen, Kathleen E. McGill Univ Dept Physiol Aerosp Med Res Unit Montreal PQ Canada McGill Univ Dept Phys Montreal PQ Canada

Massot C, Chacron MJ, Cullen KE. Information transmission and detection thresholds in the vestibular nuclei: single neurons vs. population encoding. J Neurophysiol 105: 1798-1814, 2011. First published February 9, 2011;doi:10.1152/jn.00910.2010.-Understanding how sensory neurons transmit information about relevant stimuli remains a major goal in neuroscience. Of particular relevance are the roles of neural variability and spike timing in neural coding. Peripheral vestibular afferents display differential variability that is correlated with the importance of spike timing;regular afferents display little variability and use a timing code to transmit information about sensory input. Irregular afferents, conversely, display greater variability and instead use a rate code. We studied how central neurons within the vestibular nuclei integrate information from both afferent classes by recording from a group of neurons termed vestibular only (VO) that are known to make contributions to vestibulospinal reflexes and project to higher-order centers. We found that, although individual central neurons had sensitivities that were greater than or equal to those of individual afferents, they transmitted less information. In addition, their velocity detection thresholds were significantly greater than those of individual afferents. This is because VO neurons display greater variability, which is detrimental to information transmission and signal detection. Combining activities from multiple VO neurons increased information transmission. However, the information rates were still much lower than those of equivalent afferent populations. Furthermore, combining responses from multiple VO neurons led to lower velocity detection threshold values approaching those measured from behavior (degrees 2.5 vs. 0.5-1 degrees/s). Our results suggest that the detailed time course of vestibular stimuli encoded by afferents is not transmitted by VO neurons. Instead, they suggest that higher vestibular

关键词： vestibular neurons neural variability information processing neural coding population coding

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Method for stationarity-segmentation of spike train data with application to the Pearson cross-correlation

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JOURNAL OF NEUROPHYSIOLOGY 2013年第2期110卷 562-572页

作者： Quiroga-Lombard, Claudio S. Hass, Joachim Durstewitz, Daniel Heidelberg Univ Med Fac Mannheim Cent Inst Mental Hlth Bernstein Ctr Computat Neurosci D-68159 Mannheim Germany

Correlations among neurons are supposed to play an important role in computation and information coding in the nervous system. Empirically, functional interactions between neurons are most commonly assessed by cross-correlation functions. Recent studies have suggested that pairwise correlations may indeed be sufficient to capture most of the information present in neural interactions. Many applications of correlation functions, however, implicitly tend to assume that the underlying processes are stationary. This assumption will usually fail for real neurons recorded in vivo since their activity during behavioral tasks is heavily influenced by stimulus-, movement-, or cognition-related processes as well as by more general processes like slow oscillations or changes in state of alertness. To address the problem of nonstationarity, we introduce a method for assessing stationarity empirically and then "slicing" spike trains into stationary segments according to the statistical definition of weak-sense stationarity. We examine pairwise Pearson cross-correlations (PCCs) under both stationary and nonstationary conditions and identify another source of covariance that can be differentiated from the covariance of the spike times and emerges as a consequence of residual nonstationarities after the slicing process: the covariance of the firing rates defined on each segment. Based on this, a correction of the PCC is introduced that accounts for the effect of segmentation. We probe these methods both on simulated data sets and on in vivo recordings from the prefrontal cortex of behaving rats. Rather than for removing nonstationarities, the present method may also be used for detecting significant events in spike trains.

关键词： weak-sense stationarity neural coding in vivo electrophysiology neural dynamics information statistics

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A novel test to determine the significance of neural selectivity to single and multiple potentially correlated stimulus features

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JOURNAL OF NEUROSCIENCE METHODS 2012年第1期210卷 49-65页

作者： Ince, Robin A. A. Mazzoni, Alberto Bartels, Andreas Logothetis, Nikos K. Panzeri, Stefano Ist Italiano Tecnol Robot Brain & Cognit Sci Dept I-16163 Genoa Italy Max Planck Inst Biol Cybernet D-72076 Tubingen Germany Bernstein Ctr Computat Neurosci Tubingen Germany Univ Tubingen Ctr Integrat Neurosci Vis & Cognit Lab D-72076 Tubingen Germany Univ Manchester Div Imaging Sci & Biomed Engn Manchester M13 9PT Lancs England Univ Glasgow Inst Neurosci & Psychol Glasgow Lanark Scotland

Mutual information is a principled non-linear measure of dependence between stochastic variables, which is widely used to study the selectivity of neural responses to external stimuli. Here we define and develop a set of novel statistical independence tests based on mutual information, which quantify the significance of neural selectivity to either single features or to multiple, potentially correlated stimulus features like those often present in naturalistic stimuli. If the values of different features are correlated during stimulus presentation, it is difficult to establish if one feature is genuinely encoded by the response, or if it instead appears to be encoded only as a side effect of its correlation with another genuinely represented feature. Our tests provide a way to disambiguate between these two possibilities. We use realistic simulations of neural responses tuned to one or more correlated stimulus features to investigate how limited sampling bias correction procedures affect the statistical power of such independence tests, and we characterize the regimes in which the distribution of information values under the null hypothesis can be approximated by simple distributions (Chi-square or Gaussian). Finally, we apply these tests to experimental data to determine the significance of tuning of the band limited power (BLP) of the gamma [30-100 Hz] frequency range of the primary visual cortical local field potential to multiple correlated features during presentation of naturalistic movies. We show that gamma BLP carries significant, genuine information about orientation, space contrast and time contrast, despite the strong correlations between these features. (C) 2011 Elsevier B.V. All rights reserved.

关键词： Vision LFP neural coding Natural movies Mutual information Oscillations Gamma band

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coding movement direction by burst firing in electrosensory neurons

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JOURNAL OF NEUROPHYSIOLOGY 2011年第4期106卷 1954-1968页

作者： Khosravi-Hashemi, Navid Fortune, Eric S. Chacron, Maurice J. McGill Univ Dept Physiol Montreal PQ Canada McGill Univ Ctr Appl Math Biol & Med Montreal PQ Canada Johns Hopkins Univ Dept Psychol & Brain Sci Baltimore MD USA Johns Hopkins Univ Dept Neurosci Baltimore MD USA

Khosravi-Hashemi N, Fortune ES, Chacron MJ. coding movement direction by burst firing in electrosensory neurons. J Neurophysiol 106: 1954-1968, 2011. First published July 20, 2011;doi: 10.1152/jn. 00116.2011.-Directional selectivity, in which neurons respond strongly to an object moving in a given direction ("preferred") but respond weakly or not at all to an object moving in the opposite direction ("null"), is a critical computation achieved in brain circuits. Previous measures of direction selectivity have compared the numbers of action potentials elicited by each direction of movement, but most sensory neurons display patterning, such as bursting, in their spike trains. To examine the contribution of patterned responses to direction selectivity, we recorded from midbrain neurons in weakly electric fish and found that most neurons responded with a combination of both bursts and isolated spikes to moving object stimuli. In these neurons, we separated bursts and isolated spikes using an interspike interval (ISI) threshold. The directional bias of bursts was significantly higher than that of either the full spike train or the isolated spike train. To examine the encoding and decoding of bursts, we built biologically plausible models that examine 1) the upstream mechanisms that generate these spiking patterns and 2) downstream decoders of bursts. Our model of upstream mechanisms uses an interaction between afferent input and subthreshold calcium channels to give rise to burst firing that occurs preferentially for one direction of movement. We tested this model in vivo by application of calcium antagonists, which reduced burst firing and eliminated the differences in direction selectivity between bursts, isolated spikes, and the full spike train. Our model of downstream decoders used strong synaptic facilitation to achieve qualitatively similar results to those obtained using the ISI threshold criterion. This model shows that direction selective information carried by

关键词： direction selectivity neural coding weakly electric fish action potential patterning

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Prospective contributions of transgenic mouse models to central auditory research

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BRAIN RESEARCH 2006年第1期1091卷 217-223页

作者： Liu, Robert C. Emory Univ Biol Rollins Res Ctr Atlanta GA 30322 USA

Neuroscientists are increasingly embracing mice as a means to address central nervous system questions at a molecular level. Examples abound from sensory systems like olfaction and vision. The use of mice to study central auditory processing, however, has remained relatively limited. In this commentary, I draw on some of the successes from other fields to highlight directions in which mouse models may contribute valuable and other-wise unattainable insights into the neural circuitry and plasticity within central auditory stations. Efforts towards this are beginning and would benefit from increased collaboration to generate useful transgenic mouse models for such studies. (c) 2006 Elsevier B.V. All rights reserved.

关键词： neuroethology experience dependent plasticity neural coding communication maternal behavior auditory cortex hearing

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