Properties of auditory temporal integration revealed by mismatch negativity

The mismatch negativity (MMN), a component of event-related potentials (ERP), was recorded to investigate the properties of the storage of auditory temporal sequences in the sensory memory. First, the MMN elicited by the infrequent change in a pair of closely spaced tones was evaluated. In ignored condition, it was shown that the MMN was elicited only when the total duration of the tone pair was less than 400 ms. However in attended condition, MMN was also elicited when the duration was 500 ms. This result showed that the function of "temporal integration", which integrated the short time history by using a time window, existed in sensory memory, and its maximum period was between 300 ms-400 ms, but this period could be prolonged by the attention process. Second, the relationship between temporal configuration of tone sequence and elicited MMN was evaluated. Temporal configuration was changed by inserting additional tones between the two tones in the tone pair. From this experiment, it was suggested that the performance of auditory sensory memory was influenced by the temporal configuration of the tone sequence to be stored, as well as its total duration. These results may help to approach the neuronal mechanism of auditory scene analysis.