It has been demonstrated in acute experiments in cats anesthetized with nembutal and immobilized with ditilin [succinylcholine iodide — Translator] that the number of neurons of the caudate nucleus responding to a single stimulation of the motor cortex with action potentials with a latent period less than 8.0 msec in the first 10–12 days after a course of injections of MPTP (5 mg/kg daily for 5 days, intramuscularly) decreased significantly as compared with the control. Their number is gradually restored by the 45th–54th day after the administration of the neurotoxin. A one-time injection of the dopaminomimetic, apomorphine (5 mg/kg, intramuscularly), also significantly decreases the number of neurons with a latent period of the responses less than 8.0 msec for 5 h in the intact animals, and is incapable of removing the blockade of the corticoneostriatal impulse activity in animals with an MPTP-induced dopamine deficit. The hypothesis is advanced that dopamine exerts a protective inhibitory influence on the conduction of corticofugal glutamatergic impulse activity to neurons of the neostr