Cortical lesions increase reinnervation of the dorsal striatum by substantia nigra grafts.

Effects of aspiration lesions of the cerebral cortex on intraventricular substantia nigra grafts were investigated. Increased reinnervation of the dorsal striatum was observed in animals with cortical aspirations. This reinnervation was confined to the dorsal one-fourth of the striatum, immediately underneath the cortical lesions. The increased reinnervation of the striatum by substantia nigra grafts in animals with cortical lesions is suggested to be related either to secretion of neurotrophic substances by the injured brain tissue or to removal of competition between corticostriatal inputs and graft-derived neurites for synaptic contacts.