Modulation of the amplitude of γ-band activity by stimulus phase enhances signal encoding

Authors

  • Thomas Hoch,

    1. Neural Information Processing Group, Berlin University of Technology, Germany
    2. Bernstein Center for Computational Neuroscience, Berlin University of Technology, Germany
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  • Stanislav Volgushev,

    1. Faculty for Mathematics, Ruhr University Bochum, Germany
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  • Aleksey Malyshev,

    1. Department of Neurophysiology, Ruhr University Bochum, Germany
    2. Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
    3. Department of Psychology, University of Connecticut, Storrs, CT 06269, USA
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  • Klaus Obermayer,

    1. Neural Information Processing Group, Berlin University of Technology, Germany
    2. Bernstein Center for Computational Neuroscience, Berlin University of Technology, Germany
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  • Maxim Volgushev

    1. Department of Neurophysiology, Ruhr University Bochum, Germany
    2. Institute of Higher Nervous Activity and Neurophysiology, Russian Academy of Sciences, Moscow, Russia
    3. Department of Psychology, University of Connecticut, Storrs, CT 06269, USA
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Maxim Volgushev, 6Department of Psychology, as above.
E-mail: maxim.volgushev@uconn.edu

Abstract

Visual stimulation often leads to elevated fluctuations of the membrane potential in the γ-frequency range (25–70 Hz) in visual cortex neurons. Recently, we have found that the strength of γ-band fluctuations is coupled to the oscillation of the membrane potential at the temporal frequency of the stimulus, so that the γ-band fluctuations are stronger at depolarization peaks, but weaker at troughs of the stimulus frequency oscillation of the membrane potential. We hypothesized that this coupling may improve stimulus encoding. Here, we tested this hypothesis by using a single-compartment conductance-based neuron model, with parameters of the input adjusted to reproduce typical features of membrane potential and spike responses, recorded in cat visual cortical neurons in vivo during the presentation of moving gratings. We show that modulation of the γ-range membrane potential fluctuations by the amplitude of the slow membrane depolarization greatly improves stimulus encoding. Moreover, changing the degree of modulation of the γ-activity by the low-frequency signal within the range typically observed in visual cortex cells had a stronger effect on both the firing rates and information rates than changing the amplitude of the low-frequency stimulus itself. Thus, modulation of the γ-activity represents an efficient mechanism for regulation of neuronal firing and encoding of the temporal characteristics of visual stimuli.

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