Visual object separation resolves competitive interactions in somatosensory cortex evoked signals during concurrent vibrotactile stimulation of the left and right hand.

We investigated the effect of visual separation of left and right hemispaces within peripersonal space to sustained tactile spatial attention processing and showed that visually perceived object separation weakened the competitive interaction for concurrent vibrotactile stimulation to two hands. Participants received concurrent vibrotactile stimulation at different frequencies on two hands (right: 20Hz; left: 24Hz) for 4500ms to elicit steady-state somatosensory evoked potentials (SSSEPs). They attended to one of the stimulated hands and reacted to rare transient events embedded in the attended ongoing stream. Behavioral and neurophysiological results reveal that separation of spatial representation of tactile event locations could facilitate bilateral tactile spatial selection in sustained attention processing. Visual separation by a gap between hands increased the magnitude of attentional gain in SSSEPs compared to the situation when no gap was present. Results suggest that visual separation resolved the competition between concurrent tactile stimulation on two hands.