Projections from behaviorally-defined sectors of the prefrontal cortex to the basal ganglia, septum, and diencephalon of the monkey

Subcortical fiber degeneration in Macaca mulatta was traced by means of Nauta's technique following lesions of behaviorally-defined prefrontal sectors: dorsal, principalis, lateral orbital and medial orbital, and the finest differentiation among the projections was observed in the head of the caudate nucleus.

Abstract

Subcortical fiber degeneration in Macaca mulatta was traced by means of Nauta's technique following lesions of behaviorally-defined prefrontal sectors: dorsal, principalis, lateral orbital and medial orbital. All lesions led to degeneration in parts of the anterior basal ganglia, hippocampus, medial, ventral and intralaminar thalamic nuclei, and subthalamic region. Within most of these structures, however, at least two different patterns of degeneration could be distinguished: an "orbital" pattern which differed from a "dorsolateral" one mainly in being more ventral and caudal in the basal ganglia, and more medial and denser in the thalamus and subthalamus. In addition, only orbital lesions sent fibers to the septum, or, in any substantial number, to the lateral hypothalamus. The finest differentiation among the projections was observed in the head of the caudate nucleus where each type of prefrontal lesion distributed fibers to a different locus. An attempt was made to relate the anatomical findings to behavioral studies of prefrontal-subcortical functions.