A neuroanatomical analysis of the rostral striatopallidal pathway in the rat

Anterograde and retrograde experiments were made in the rat using either a mixture of horseradish peroxidase free and wheat germ-agglutinated (HRP-WGA) or HRP-WGA unmixed, in an attempt to investigate how the striatopallidal pathway is organized from rostral territories of the rat's striatum. The main findings emerging from this study are: a) a remarkable projection is directed from the rostral pole of the caudate-putamen complex to rostral sectors of the globus pallidus (GP) and entopeduncular nucleus (EP) and its is organized in a topographical fashion; b) this projection presents a remarkable heterogeneity in the distribution of terminal labeling into the GP and EP; c) a heterogeneous distribution of retrogradely labeled cells was seen in the rostral striatum after retrograde tracer injections in the GP that might explain, at least partially, the heterogeneity observed in the anterograde experiments.