Functional organization of the basal ganglia: therapeutic implications for Parkinson’s disease. Movement Disorders

Abstract: The basal ganglia (BG) are a highly organized net-work, where different parts are activated for specific func-tions and circumstances. The BG are involved in movement control, as well as associative learning, planning, working memory, and emotion. We concentrate on the ‘‘motor cir-cuit’ ’ because it is the best understood anatomically and physiologically, and because Parkinson’s disease is mainly thought to be a movement disorder. Normal function of the BG requires fine tuning of neuronal excitability within each nucleus to determine the exact degree of movement facilita-tion or inhibition at any given moment. This is mediated by the complex organization of the striatum, where the excitabil-ity of medium spiny neurons is controlled by several pre-and postsynaptic mechanisms as well as interneuron activity, and secured by several recurrent or internal BG circuits. Th