THE (IN-)VISIBLE TOUCH: MULTI-SENSORY ENTRAINMENT OF VISUAL-SOMATOSENSORY ALPHA COHERENCE AND ITS EFFECT ON VISUAL-TACTILE INTEGRATION

Holistic perception of a high-dimensional world like ours requires constant interactions between the different senses. Prior research suggests that this cross-modal integration might be achieved through oscillatory coherence (i.e., phase synchronization) between the respective sensory areas. Successful visual-tactile integration, for example, has previously been associated with increased alpha (i.e., 8-12 Hz) coherence between visual and somatosensory cortices. The causal relevance of oscillatory coherence for cross-modal integration, however, remains a matter of ongoing research. Here, we used electroencephalography (EEG) together with 10 Hz visual flicker and 10 Hz vibro-tactile flutter to record and non-invasively manipulate visual-somatosensory alpha coherence during the execution of a visual-tactile integration task. Preliminary results suggest that rhythmic compared to arhythmic (i.e., control) visual-tactile stimulation increased alpha power, steady-state evoked potentials and flicker-brain/inter-areal coherence in visual and somatosensory cortices. In line with the suggested role of alpha coherence for visual-tactile integration, this change in alpha coherence was mirrored by a behavioral benefit for the rhythmic vs. arhythmic condition. Our results suggest that it might be possible to manipulate inter-areal coherence using multi-sensory entrainment and that alpha coherence could indeed causally support cross-modal integration.