Ganglia, basal: A region located at the base of the brain composed of 4 clusters of neurons, or nerve cells. This area of the brain is responsible for body movement and coordination. The groups of neurons most prominently and consistently affected in Huntington disease -- the pallidum and striatum -- are located in the basal ganglia. (The pallidum is composed of structures called the globus pallidus and the ventral pallidum while the striatum consists of the caudate nucleus, putamen, and ventral striatum.) The term "basal ganglia" refers to the location of these collections of neurons (ganglia) deep within the brain, seemingly at its very base.