Abstract
Purpose and methods In order to investigate spatio-temporal profiles of auditory visual integration in human brain, we measured human MagnetoEncepharoGram (MEG) activities when auditory pip signals and visual Gabor signals were presented either (1) simultaneously or (2) asynchronously with the time delay of +/- 300ms with the auditory duration of 30ms and visual duration of 100ms. These were compared with MEG signals with only auditory or visual stimulations. Results We found a significant increase of MEG activities around SOA of 160ms in the posterior inferotemoporal visual area when auditory and visual signals were presented simultaneously without time delay. The magnitude of the activities significantly increased compared with that of visual only, or auditory only conditions. Such activities disappeared with the time delay of +/− 300ms. Furthermore, the evoked response of SOA around 100ms enhanced possibly due to rapid interaction from visual to auditory streams. Discussion These results indicate that visual and auditory signals were integrated at the high level visual area of IT when they are presented simultaneously with relatively fast time course, demonstrating non-linear integration process of auditory visual signals in the human brain.