Neuromagnetic analysis of effect of audition-based prediction on visual information processing

The aim of this study is to examine if the mechanism of detecting incongruities between preceding auditory information and following visual information at the early stage exists by means of magnetoencephalography (MEG). In analogy to a piano keyboard, pictures of two adjacent keys and two kinds of tone bursts adjusted to correspond to each other were employed. Whenever an auditory stimulus was presented, a picture of either a left or right key at the down position was subsequently delivered instead of one at the initial position. Four kinds of audiovisual pairs were thus established. The congruent pairs (CP) were designed as the standard stimuli, and the incongruent pairs (IP) as the deviant stimuli. Two experiments with the intentional use/non-use of audition-based prediction were conducted. As a result, the activities in the temporo- and parieto-occipital areas for IPs were more enhanced than those for CPs in the period of 100-200 ms after the onset of visual stimulus under the prediction condition, whereas these were not recognized under the non-prediction condition. Consequently, the prediction based on the auditory information found to modulate the visual pathway explicitly, which is compared with the following visual information to detect the crossmodal incongruent pairs at the early stage.