MODULATION OF SENSORY INOUT FROM THE HAND DURING VOLUNTARY MOVENT

An early component of the somatosensory evoked potential, arising from the primary sensory cortex in man is attenuated during voluntary finger movement. The median nerve at the wrist was stimulated while the subject performed fractionated finger movements with the same hand.
Subcortical components of the somatosensory evoked potential were not changed but the P25 cortical component was attenuated. Equivalent diapole analysis shows this component originates in areas 1 and 2 of the sensory cortex.
It is proposed that the motor cortex (area 4) has an inhibitory pathway to areas 1 and 2 which is active during voluntary movements.