Spatiotemporal Dynamics of Vision on Force Control

The spatiotemporal pattern of brain activity during force control in healthy individuals using high-density electroencephalography (EEG) was examined. The first study examined the immediate transition from a visually guided to memory guided force control using event-related potentials (ERPs) and low-resolution electromagnetic tomography (LORETA). Our findings showed that subjects rely on visuomotor memory processes involving ventral premotor and ventral prefrontal cortices before any behavioral changes occurred. The second study examined the immediate transition between different spatial amplitudes of visual feedback using ERPs and LORETA. The transitions consisted of changes from low to high and high to low visual gains. Activity in the dorsal and ventral premotor cortices was identified during both changes in visual gains. Increasing visual gain involved a shift in electrocortical activity within parietal-frontal circuits that is not present during decreases in visual gain. More importantly, this parietal-frontal brain activity systematically related to force error. The transition from low to high gain involved greater changes in the superior parietal cortex, while the transition from high to low gain involved greater changes in the extrastriate cortex (V3). Our findings showed that the human visuomotor system does not respond uniformly to changes in the gain of visual feedback and that increased visual gain triggered increased force variability that was related to electrocortical activity in parietal-frontal circuits. Overall, the spatiotemporal pattern of brain activity and force performance during three different manipulations of visual feedback were investigated.