Basal Ganglia

(a) The locations of the components of the basal ganglia and associated structures. (b) The major connections of the basal ganglia and associated structures. Excitatory connections are shown as black lines; inhibitory connections are shown as red lines. The direct pathway is indicated by arrows with solid lines. The indirect pathway is indicated by arrows with broken lines. The hyperdirect pathway is indicated by arrows with dotted lines. Many connections, such as the inputs to the substantia nigra, are omitted for clarity.