Abstract
Selective total destruction of the feline substantia nigra (SN) is virtually impossible. Fulgurative lesions producing partial nigral destruction, with or without encroachment on neighboring structures, have been ineffective in producing lasting abnormalities of the sensorimotor activities of the cat. Ventral tegmental injection of 6-hydroxy-dopamine (6-OH DA) destroyed up to 70% of neurons within the SN without involving outside tissue. Such 6-OH DA-induced chemonigrectomy was associated with a persisting sensorimotor impediment characterized by compulsive circling, truncal ataxia, and, when moving from a higher to a lower place, “somersaulting” and “nosediving”. These abnormalities are similar to those produced by large lesions to the head of the caudate nucleus. These data provide additional indication that caudate effects on the sensorimotor organization are largely relayed through SN.
