UC San Diego

A key aspect of daily functioning is our ability to control our response tendencies. An experimentally tractable way to study such control is by focusing on how initiated movements are stopped and changed (action control). Previous research has elucidated a network of structurally connected regions critical for action control including the right inferior frontal cortex (IFG), the pre -supplementary motor area (preSMA), and the subthalamic nucleus (STN) of the basal ganglia. This thesis examines the functioning of this circuit in humans using a combination of electrocorticography (ECoG, providing both high spatial and temporal resolution) and electroencephalography (EEG) recorded at the scalp during stimulation of the STN. Evidence is presented for a possible mechanism of neural communication between the nodes of this network involving beta frequency oscillations. Specifically, there are beta increases in both the right IFG and preSMA, functional connectivity in beta between the two when stopping is successful, and modulation of cortical beta during action control associated with changes in stimulation of the STN. The thesis also presents evidence regarding different functional contributions of separate prefrontal regions in the performance of the action control. Specifically, it is proposed that the preSMA plays a role in task configuration, by preparing the wider network for a possible need to resolve competing response tendencies, the right IFG is engaged during the actual action control, and the dorsolateral prefrontal cortex represents action control rule