Tactile stimulation accelerates behavioral responses to visual stimuli through enhancement of occipital gamma-band activity.

We investigated how responses of occipital cortex to visual stimuli are modulated by simultaneously presented tactile stimuli. Magnetoencephalography was recorded while subjects performed a simple reaction time task. Presence of a task-irrelevant tactile stimulus leads to faster behavioral responses and earlier and stronger gamma-band synchronization in occipital cortex, irrespective of the relative location of the tactile stimulus. While also other stimulus related responses in occipital cortex were modulated (alpha-band and evoked responses in parieto-occipital region), correlation-analysis revealed induced gamma-band activity to be the best predictor of the faster behavioral response latencies, suggesting a key-role of oscillatory activity for cross-modal integration.