Neural Processing of Octave Illusion in Auditory Cortex Revealed by Frequency Tagging Method

Abstract

We measured the auditory steady state responses (ASSR) in a magnetoenchephalogram to study the mechanism of neural processing in the auditory cortex with octave illusion proposed by Diana Deutsch. Octave illusion is induced using consecutive dichotic sounds, where two tones that are one octave apart, e.g., 400 and 800 Hz, are alternated between the ears at 500-ms intervals. We then applied the frequency tagging method to the ASSRs that were recorded during the octave illusion. We compared the ASSR amplitude between non-illusion and illusion groups. The results showed that there was difference in the ASSR amplitude of the auditory cortex between the illusion and the non-illusion groups. In non-illusion group, the ASSR was showed right hemisphere dominance and contralateral activation. There was no significant difference in the illusion group. These results suggest that right hemisphere dominance and contralateral activation are related to neural processing of the octave illusion.