ABSTRACT
The basal ganglia have been traditionally considered to consist of the striatum, globus pallidus, thalamus, subthalamic nucleus (STN), substantia nigra the pedunculopon-tine nucleus and the connections between these nuclei. Based on neuroanatomical and neurophysiological studies in animal models of Parkinson's disease (PD) and electrophysiological studies in PD patients undergoing functional brain surgery, a model of basal ganglia function and pathophysiology of PD has been proposed. Putamenal output is in turn directed towards the basal ganglia output nuclei, globus pallidus internal segment and the SNr via two pathways: a 'direct' monosynaptic pathway and an 'indirect' polysynaptic pathway passing through motor areas of the external pallidal segment and the STN. Neurons within each basal ganglia nucleus have specific patterns of neuronal discharge. Using single cell neuronal recording, these neuronal discharge patterns can be recorded and analysed. In addition, Dopamine may modulate basal ganglia output through its actions at extrastriatal sites.
