These efferents terminate in the VL and VA nuclei of the thalamus. The centromedian nucleus in addition receives input from the internal segment of the globus pallidus. Regions of VA and VL that receive basal ganglia input project to the premotor and prefrontal cortices. Tremor and rigidity may return after 1-3 yrs. Some experimental evidence suggests that akinesia may result with dopamine depletion in the nucleus accumbens.
Mental functions undergo deterioration.
Loss of cholinergic neurons and GABA-ergic neurons in the striatum. Impaired cognitive functions are thought to result from simultaneous loss of cortical neurons. An imbalance is set up in the relevant biochemical pathways. L-DOPA makes the choreic movements worse. Most often seen in older people.