Auditory brain response modified by temporal deviation of language rhythm: an auditory event-related potential study

The effects of the temporal disruption of language rhythm in Japanese on auditory evoked potentials were investigated in normal subjects. Auditory event-related evoked potentials (AERP) were recorded following syllables using a natural and deviated language rhythm by inserting various (0-400 ms) silent intervals between syllables. The language speed was changed to assess the effect of a deviant rhythm relative to the language speed on AERP in another experiment. The prolonging of intervals did not affect the N100-P150 components until the inserted interval became 400 ms, while the negative component (early negativity, EN), peaking at 250-300 ms, was enhanced when the interval was 100 ms or more. The N100-P150 components following deviated language rhythms did not change during the fast speed but did in the standard and slow speed. We considered that the N100-P150 components were changed by the mixed effects of adaptation and prediction related to the reading speed, and that EN was evoked by deviated language rhythm in a different way from that caused N100-P150 changes, possibly via mismatch detection process between deviant rhythm and intrinsic rehearsed rhythm.