The Anatomy of the Basal Ganglia

The basal ganglia are a set of subcortical nuclei that receive inputs from the entire cortex and send outputs via the thalamus to different frontal cortical areas. Several parallel and segregated closed cortico-striatal-thalamo-cortical loops serve a role in selecting desirable actions and suppressing undesirable ones. The basal ganglia thereby contribute to a number of processes, including planning, decision-making, action selection, learning, sequencing, and the initiation and timing of movement. Dopamine innervation of the basal ganglia is critical for their normal function and, in particular, for learning. Here, we review the anatomy of the basal ganglia and current models of their function. We then consider these functions in the context of the human brain’s unique abilities to produce and understand speech and language. Critical questions concern whether the human basal ganglia has speech-specific and language-specific circuitry or if the speech and language impairments associated with basal ganglia dysfunction reflect more general processes.
Keywords: Striatum; direct and indirect pathways; dopamine; subcortical; Parkinson’s disease; motor control