The Basal Ganglia and the Planning of Actions

A model is presented for the low-level operation of the basal ganglia in the brain. The model posits that the basal ganglia are responsible for driving smooth transitions of state (e.g., joint positions) for an organism. This is accomplished through the computation of a potential function on which a gradient descent is performed to the desired state. The model proposes that various contiguous parts of the neostriatum correspond to state spaces, each of which pertains to a di erent aspect of the organism. The model also proposes that the neostriatum computes a potential function within each of these state spaces via electrotonic coupling, and that the local shape of this function at a given point (i.e., state) is used to drive the organism to a new state via inhibition of the globus pallidus. This paper discusses this model only in the context of motor control, i.e., egomotion and limb movement. The model appears to account for a variety of experimental results. Some implications of the model for Parkinson's and Huntington's diseases are also discussed.