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The dependence of the auditory evoked N1m decrement on the bandwidth of preceding notch-filtered noise

Authors

  • H. Okamoto,

    1. Department of Integrative Physiology, National Institute for Physiological Sciences, Myodaiji, Okazaki, 444-8585, Japan
    2. Department of Otorhinolaryngology and Sensory Organ Surgery, Osaka University Graduate School of Medicine, Osaka, Japan
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  • R. Kakigi,

    1. Department of Integrative Physiology, National Institute for Physiological Sciences, Myodaiji, Okazaki, 444-8585, Japan
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  • A. Gunji,

    1. Department of Integrative Physiology, National Institute for Physiological Sciences, Myodaiji, Okazaki, 444-8585, Japan
    2. Department of Developmental Disorders, National Center of Neurology and Psychiatry, Tokyo, Japan
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  • T. Kubo,

    1. Department of Otorhinolaryngology and Sensory Organ Surgery, Osaka University Graduate School of Medicine, Osaka, Japan
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  • C. Pantev

    1. Institute for Biomagnetism and Biosignal Analysis, University of Münster, Münster, Germany
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Dr Hidehiko Okamoto, 1Department of Integrative Physiology, as above.
E-mail: hokamoto@nips.ac.jp

Abstract

The auditory evoked response is known to be changed by a preceding sound. In this study we investigated by means of magnetoencephalography how a preceding notch-filtered noise (NFN) with different bandwidths influences the human auditory evoked response elicited by the following test stimulus. We prepared white noise (WN) and four NFNs which were derived from WN by suppressing frequency regions around 1 kHz with 1/8-, 1/4-, 1/2- and 1-octave bandwidths. Stimulation for 3 s with this set of noises resulted in differences in responsiveness to a 1-kHz test tone presented 500 ms after the offset of the noises. The N1m response to the 1-kHz test tone stimulus was at a minimum when the preceding NFN had 1/4-octave stop-band frequencies as compared with 1/8-, 1/2- and 1-octave NFN and WN. This N1m decrement is explained by the imbalanced neural activities caused by habituation and lateral inhibition in the auditory system. The results contribute to understanding of the inhibitory system in the human auditory cortex.

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