neurolove:

Basal Ganglia [Image Source]

The basal ganglia are nestled inside cortex, surrounding the thalamus (see image above).  The striatum (part of the basal ganglia circuitry) is composed of the putamen, caudate, and nucleus accumbens.  Other important parts of the basal ganglia are the globus pallidus (which has an internal and an external segment, GPi and GPe respectively) and the subthalamic nucleus (STN).

The basal ganglia function in a type of “loop” by which information enters the basal ganglia from cortex and then goes out through thalamus and back to cortex.  Different parts of striatum control the loops for emotion (nucleus accumbens), movement (putamen) or thoughts (caudate).  There are two kinds of loops for each of these systems- the direct (which is excitatory) and indirect (which is inhibitory) loops, which I will talk about in more detail in the next post.