Auditory illusion explored with MEG

Abstract

Event Abstract Back to Event Auditory illusion explored with MEG Ken-ichi Ouchi1*, Shinya Kuriki2, Asuka Otsuka3 and Makoto Takahashi1 1 Hokkaido University, Japan 2 Tokyo Denki University, Japan 3 The University of Tokyo, Elekta K.K, Japan Deutsch has shown in her paper (1975) an auditory illusion occurring when dichotic tonal sequences are given to listeners in both ascending and descending forms, in a way that a component of the ascending scale is in one ear, a component of the descending scale is in the other, and vice versa repetitively. Most right handed subjects perceived two streams of “scale illusion” where higher tones in the scale appear exclusively in one ear and other lower tones in the other. Here, we made MEG measurements to examine how the dichotic tones in a scale are represented in the right and left auditory cortices using frequency tagging, in which higher and lower tones were amplitude modulated at distinct frequencies of fH and fL. Steady state MEG responses were separated by FFT into fH and fL components. In some subjects who reported the percept of scale illusion, the amplitudes of fH and fL component of contra- (or ipsi-) and ipsi- (or contra-) lateral responses were altered from the normal relation of contralateral preference. Such increment/decrement of the responses in the auditory cortex to some component-tones in the tonal sequence might be related with the percept of scale illusion.