Effect of spatial attention on human sensorimotor integration studied by transcranial magnetic stimulation

Objective: Recent transcranial magnetic stimulation (TMS) studies showed that the sensory input can decrease the motor cortex excitability (afferent inhibition). To clarify the effect of attention on sensorimotor integration, we investigated the effect of spatial attention on afferent inhibition. Methods: Right median nerve electrical stimulation followed, at variable delays (10–300 ms), by TMS over the left motor cortex was applied to 9 subjects, during 3 conditions; spatial attention to the right and left hand, and control (no attention) tasks. Results: Inhibition of the motor evoked potential occurred at inter-stimulus interval of 20 and 100 ms, which was more was marked during spatial attention to the right than to the left hand. Conclusions Enhancement of the afferent inhibition induced by spatial attention to the stimulated side is likely to reflect the interaction between attention and sensorimotor integration. Significance: The spatial attention may modulate the sensorimotor integration studied by afferent inhibition of the MEP.