Only a stimulus onset might initiate the temporal window of integration

The acoustic brain has the ability to detect the deviant sounds in the series of homogeneous sounds. The mismatch negativity (MMN) is considered to reflect this ability. Various types of deviations including the omission of sound can elicit MMN. MMN is generated by the comparison process between sound change and the memory trace of the preceding sounds stored in sensory memory. When the trace of sound is formed in sensory memory, the mechanism termed the temporal window of integration (TWI) which integrates the closely presented sounds into single units is activated. MMN to omission has provided the evidence for the presence of TWI mechanism. MMNs were elicited by the omitted tones only when SOAs were shorter than 160 ms. It suggests a temporal correspondence between the duration of the neural sound representations in sensory memory and the TWI of 160–170 ms. However, nobody knows whether TWI is initiated by the stimulus onset or not. Therefore, we tried to clarify what initiates the TWI as reflected by MMN. We employed four types of stimulus pairs of the deviants and standards which were different in duration. Finally, we found that the onset of stimulus initiated the TWI, and the TWI did not slide with the stimulus.