FIGURE 11-13 Regulating Movement Force Two pathways in the basal ganglia modulate movements produced in the cortex. Green pathways are excitatory; red are inhibitory. The indirect pathway excites the globus pallidus internal, whereas the direct pathway has an inhibitory effect. If activity in the indirect pathway dominates, the thalamus shuts down, and the cortex is unable to produce movement. If direct-pathway activity dominates, the thalamus can become overactive, amplifying movement.

Information from R. E. Alexander & M. D. Crutcher (1990). Functional architecture of basal ganglia circuits: Neural Substrates of parallel processing. Trends in Neuroscience, 13, p. 269.