Interactive processing of sensory input and motor output in the human hippocampus

Recent studies of visuomotor integration suggest that the motor system ma b e intimately involved in the detection of salient features of the sensory s cene. The final stages of sensor processing occur in hippocampal structures . We measured human neuromagnetic responses during motor reaction to an aud itor cue embedded in high-speed multimodal stimulation. Our results demonst rate that large-scale cognitive networks may recruit additional resources f rom the hippocampus during sensorimotor integration. Hippocampal activity f rom 300 msec before to 200 msec after cued movements was enhanced significa ntly over that observed during self-paced movements. The dominant hippocamp al activity appeared equally synchronized to both sensory input and motor o utput, consistent with timing by an intrinsic mechanism, possibly provided by ongoing theta oscillations.