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

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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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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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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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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On the use of information theory for the analysis of the relationship between neural and imaging signals

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MAGNETIC RESONANCE IMAGING 2008年第7期26卷 1015-1025页

作者： Panzeri, Stefano Magri, Cesare Logothetis, Nikos K. Italian Inst Technol Robot Brain & Cognit Sci Dept I-16163 Genoa Italy Univ Manchester Fac Life Sci Manchester M60 1QD Lancs England Univ Milan Dipartimento Informat & Comunicaz I-20135 Milan Italy Max Planck Inst Biol Cybernet D-72076 Tubingen Germany Univ Manchester Manchester M13 9PT Lancs England

Functional magnetic resonance imaging (fMRI) is a widely used method for studying the neural basis of cognition and of sensory function. A potential problem in the interpretation of fMRI data is that fMRI measures neural activity only indirectly, as a local change of deoxyhemoglobin concentration due to the metabolic demands of neural function. To build Correct sensory and cognitive maps in the human brain, it is thus crucial to Understand whether fMRI and neural activity convey the same type of information about external correlates. While a substantial experimental effort has been devoted to the simultaneous recordings of hemodynamic and neural signals, so Far, the development of analysis method, that elucidate how neural and hemodynamic signals represent sensory information has received less attention. In this article, we critically review why the analytical framework of information theory, the mathematical theory of communication, is ideally suited to this purpose. We review the principles of information theory and explain how they could be applied to the analysis of fMRI and neural signals. We how that a critical advantage of information theory over more traditional analysis paradigms commonly used in the fMRI literature is that it can elucidate, within a single framework, whether an empirically observed correlation between neural and fMRI signals reflects either a similar stimulus tuning or a common source of variability unrelated to the external stimuli. In addition, information theory determines the extent to which these shared sources of stimulus signal and of variability lead PORI and neural signals to convey similar information about external correlates. We then illustrate the formalism by applying it to the analysis of the information carried by different bands of the local field potential. We conclude by discussing the current methodological challenges that need to be addressed to make the information-theoretic approach more robustly applicable to the si

关键词： BOLD local field potential neural coding

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Conditional modeling and the jitter method of spike resampling

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JOURNAL OF NEUROPHYSIOLOGY 2012年第2期107卷 517-531页

作者： Amarasingham, Asohan Harrison, Matthew T. Hatsopoulos, Nicholas G. Geman, Stuart Brown Univ Div Appl Math Providence RI 02912 USA CUNY Dept Math New York NY 10021 USA CUNY Grad Ctr Program Cognit Neurosci New York NY 10021 USA Univ Chicago Dept Organismal Biol & Anat Comm Computat Neurosci & Neurobiol Chicago IL 60637 USA

Amarasingham A, Harrison MT, Hatsopoulos NG, Geman S. Conditional modeling and the jitter method of spike resampling. J Neurophysiol 107: 517-531, 2012. First published October 26, 2011;doi:10.1152/jn.00633.2011.-The existence and role of fine-temporal structure in the spiking activity of central neurons is the subject of an enduring debate among physiologists. To a large extent, the problem is a statistical one: what inferences can be drawn from neurons monitored in the absence of full control over their presynaptic environments? In principle, properly crafted resampling methods can still produce statistically correct hypothesis tests. We focus on the approach to resampling known as jitter. We review a wide range of jitter techniques, illustrated by both simulation experiments and selected analyses of spike data from motor cortical neurons. We rely on an intuitive and rigorous statistical framework known as conditional modeling to reveal otherwise hidden assumptions and to support precise conclusions. Among other applications, we review statistical tests for exploring any proposed limit on the rate of change of spiking probabilities, exact tests for the significance of repeated fine-temporal patterns of spikes, and the construction of acceptance bands for testing any purported relationship between sensory or motor variables and synchrony or other fine-temporal events.

关键词： spike timing neural coding jitter hypothesis testing conditional inference synchrony

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