Corticostriate projections from reciprocally connected sectors of areas 4 and 5 in the dog.

Injections of tritiated leucine were made into area 4 on the medial part of the posterior sigmoid gyrus and area 5 on the rostral part of the lateral gyrus. Both areas were found to project to each other as well as to an overlapping area in the caudate nucleus. These data suggest that areas 4 and 5 in the dog may relate to each other not only through direct reciprocal connections but also through overlapping projections to the neostriatum.