Primarily, antagonism of dopamine D2 receptors in the striatum disinhibits GABA neurons, enkephalin, and the subthalamic nucleus in the indirect pathway, leading to increased GABA inhibition in the thalamocortical projection, causing a relative decrease in the activity of thalamocortical circuits, resembling the motor loop impairment similar to that seen in Parkinson's disease [14]. Here, DRD2 is linked to Parkinson disease.