Figure 3.

Deep brain stimulation (DBS) of the internal segment of the globus pallidus (GPi) disrupts information flow through the GPi. (A, B) Effects of local GPi-DBS on cortically evoked responses of a GPi neuron in a normal monkey. PSTHs in response to a single-pulse stimulation of the primary motor cortex (Cx) (arrowhead with dotted line) without (A) and with GPi-DBS (arrows) (B) are shown. In (B), cortical stimulation was applied 50 ms after the initiation of GPi-DBS. The cortically evoked responses were entirely inhibited during GPi-DBS. (C) Schematic diagram showing the cortico-basal ganglia pathways and stimulating (Stim and DBS) and recording (Rec) sites. Cortically evoked early excitation, inhibition and late excitation in (A) are mediated by the hyperdirect, direct, and indirect pathways, respectively. Cx, cerebral cortex; GPe, external segment of the globus pallidus; STN, subthalamic nucleus. Red and blue triangles represent glutamatergic excitatory and GABAergic inhibitory terminals, respectively. Modified from Chiken and Nambu (2013).