The corticostriatal and corticotectal projections of the feline lateral suprasylvian cortex demonstrated with anterograde biocytin and retrograde fluorescent techniques.

The relationship between the visual cortex and the striatum (ST) of the cat is poorly understood. The present experiments were an attempt to determine if regions along the lateral suprasylvian cortex (LS), known to send dense visual projections to the superior colliculus (SC), also project to the striatum and, if so, to determine whether corticostriatal and corticotectal axons arise from the same neurons. Injections of the anterograde tracer, biocytin, into the posterior portion of the lateral suprasylvian cortex resulted in dense label in both ST and SC. In ST, labeled fibers and terminals were found predominantly in the caudal part of the head of the ipsilateral caudate nucleus and the caudal portion of the ipsilateral putamen. These injections also resulted in label in the superficial and deep laminae of SC. After paired injections of retrogradely transported fluorescent dyes (dextran tetramethylrhodamine and dextran fluorescein) into ST and SC, numerous labeled LS neurons were observed in layer V and modest numbers in layer III: the corticostriatal neurons were found in layers III and V whereas corticotectal neurons were seen only in layer V. Although labeled neurons from each injection were intermingled in layer V, very few of them were double-labeled. These data suggest that while ST and SC receive substantial visual inputs from the same cortical area, the nature of the information they receive may be quite different.