Fiber Connections of the Basal Ganglia

Abstract

This chapter aims to incorporate the results of recent work on the anatomy into a general outline of the fiber connections of the basal ganglia. Progress of two types can be identified based on the anatomical studies of the basal ganglia: conformations and modifications of earlier findings, and major new conclusions as to the organization of the basal ganglia and their allied nuclei. Three major findings have singled out as representing not simply revisions but conclusions novel enough to reorient some lines of work on the basal ganglia. The first of these is the discovery of a high degree of compartmentalization within the striatum. The second major conclusion is that the nuclei allied to the corpus striatum proper provide not only important points of access into the circuitry of the basal ganglia but also outlets that extend the influence of the basal ganglia well beyond the confines of the traditional outflow channel from corpus striatum to thalamus to motor cortex. The third conclusion is that the two great subcortical divisions of the cerebral hemisphere—the corpus striatum and limbic system—are by no means insulated from one another but instead are tied together by pathways that over successive synaptic linkages lose their identities as skeletomotor or limbic.