複合音の時間特性による聴覚誘発MEG応答の変化

抄録

We investigated effects of the temporal waveform of complex sounds, which were delivered repeatedly to subjects, on the latency and amplitude of N1m and P2m responses of auditory evoked fields. Two components appeared in early and late latencies in P2m response, which led us to analyze these components separately. It was found that the change in the periodic waveform of sounds, while the frequency spectrum was kept nearly constant, affected the amplitude of N1m but not P2m. The latency and adaptation, i.e., how the response amplitude was attenuated by repetition of stimulus sounds, were affected by the phase and periodicity of the waveform, in different manners for the two components of P2m. The results indicated that the N1m response was sensitive mostly to the periodicity, while the two P2m components were dependent both on the phase and periodicity of complex sounds. We discussed possible relation between the processing of sound features and the neural substrates of N1m and P2m responses.