1. Computational and Systems Biology
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Speech encoding by coupled cortical theta and gamma oscillations

  1. Alexandre Hyafil  Is a corresponding author
  2. Lorenzo Fontolan
  3. Claire Kabdebon
  4. Boris Gutkin
  5. Anne-Lise Giraud
  1. Ecole Normale Supérieure, France
  2. University of Geneva, Switzerland
Research Article
  • Cited 65
  • Views 3,013
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Cite this article as: eLife 2015;4:e06213 doi: 10.7554/eLife.06213

Abstract

Many environmental stimuli present a quasi-rhythmic structure at different timescales that the brain needs to decompose and integrate. Cortical oscillations have been proposed as instruments of sensory de-multiplexing, i.e., the parallel processing of different frequency streams in sensory signals. Yet their causal role in such a process has never been demonstrated. Here we used a neural microcircuit model to address whether coupled theta-gamma oscillations, as observed in human auditory cortex, could underpin the multiscale sensory analysis of speech. We show that, in continuous speech, theta oscillations can flexibly track the syllabic rhythm and temporally organize the phoneme-level response of gamma neurons into a code that enables syllable identification. The tracking of slow speech fluctuations by theta oscillations, and its coupling to gamma-spiking activity both appeared as critical features for accurate speech encoding. These results demonstrate that cortical oscillations can be a key instrument of speech de-multiplexing, parsing, and encoding.

Article and author information

Author details

  1. Alexandre Hyafil

    INSERM U960, Group for Neural Theory, Département d'Etudes Cognitives, Ecole Normale Supérieure, Paris, France
    For correspondence
    alexandre.hyafil@gmail.com
    Competing interests
    The authors declare that no competing interests exist.
  2. Lorenzo Fontolan

    INSERM U960, Group for Neural Theory, Département d'Etudes Cognitives, Ecole Normale Supérieure, Paris, France
    Competing interests
    The authors declare that no competing interests exist.
  3. Claire Kabdebon

    INSERM U960, Group for Neural Theory, Département d'Etudes Cognitives, Ecole Normale Supérieure, Paris, France
    Competing interests
    The authors declare that no competing interests exist.
  4. Boris Gutkin

    INSERM U960, Group for Neural Theory, Département d'Etudes Cognitives, Ecole Normale Supérieure, Paris, France
    Competing interests
    The authors declare that no competing interests exist.
  5. Anne-Lise Giraud

    Department of Neuroscience, University of Geneva, Geneva, Switzerland
    Competing interests
    The authors declare that no competing interests exist.

Reviewing Editor

  1. Hiram Brownell, Boston College, United States

Publication history

  1. Received: December 23, 2014
  2. Accepted: May 28, 2015
  3. Accepted Manuscript published: May 29, 2015 (version 1)
  4. Accepted Manuscript updated: June 5, 2015 (version 2)
  5. Version of Record published: June 25, 2015 (version 3)

Copyright

© 2015, Hyafil et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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