Approach of visual stimuli facilitates the prediction of tactile events and suppresses beta band oscillations around the primary somatosensory area.

The purpose of the present study was to investigate whether the approach of visual stimuli influences prediction of subsequent tactile events. For this purpose, we examined electroencephalograms (EEGs) during the prediction of tactile events when visual stimuli did or did not approach. Tactile stimuli were presented with a high probability (80%) of being applied to the left (or right) index finger and a low probability (20%) of being applied to the opposite index finger. In the approach condition, visual stimuli were presented towards the hand to which the high-probability tactile stimuli were presented; in the neutral condition, visual stimuli did not approach. The result of time-frequency analysis for the EEGs showed that beta band event-related spectral perturbation at the electrodes around the primary somatosensory area (C3 and C4) was suppressed about 300 ms before the presentation of a tactile stimulus and that event-related desynchronization (ERD) occurred in all conditions. Moreover, the beta band ERD of the approach condition was larger than that of the neutral condition. These results provide evidence that the approach of visual stimuli facilitates prediction itself for subsequent tactile events.