Neuromagnetic Responses are Modulated by Endogenous Factors

Abstract

A neuromagnetic response, N1m, is elicited in the auditory cortex at around 100 ms after onset of input sound. The amplitude of the N1m response reflects acoustic properties of sounds such as spectral characteristics, loudness and frequency overlap with the preceding sound. On the other hand, the auditory cortex elicits an N1m-like response when a sound is mentally imagined or expected at a certain timing. We studied effects of such endogenous factors on the modulation of N1m response to chords that are musically unfolded in sequence. We observed that the N1m response was significantly larger when the chord sequence was unfolded to be musically closed as compared to the control chords presented sequentially but not in form of musical progression. We infer that the N1m response was augmented as a result of listeners' expectation for the final chord that closes the sequence musically.