Chapter 25 What features of visually guided arm movements are encoded in the simple spike discharge of cerebellar Purkinje cells?

This chapter examines what is currently known about the encoding of limb movement parameters in the cerebellum, including some of the recent observations, and examines the discharge properties of Purkinje cells for reaching movements throughout the horizontal workspace.

Abstract

The cerebellar cortex and nuclei play a major role in the production of smooth, coordinated movements. There is a host of hypotheses on the cerebellum's role in motor behavior. Testing the validity of any hypothesis of cerebellar function requires defining the kinematic or dynamic parameters encoded or represented in the discharge of cerebellar neurons. This step is crucial to the understanding of the controlled variables and the information processed by the cerebellum. This conceptual approach forms the basis for this chapter and examines what is currently known about the encoding of limb movement parameters in the cerebellum, including some of the recent observations. Emphasis is placed on the simple spike discharge of Purkinje cells. Purkinje cells, as well as dentate and interposed neurons, are reported to possess directionally sensitive discharge in single joint and multijoint movements. To provide a more complete description of the encoding of kinematics, the discharge properties of Purkinje cells for reaching movements throughout the horizontal workspace are evaluated. One salient finding is that the simple spike discharge of Purkinje cells is spatially tuned. Each cell's simple spike discharge defines a movement field.