Delayed matching-to-sample, object retrieval, and discrimination reversal deficits in chronic low dose MPTP-treated monkeys.

Cognitive deficits following chronic exposure to low doses of the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) were studied in monkeys asymptomatic for a gross parkinsonian motor disorder. Monkeys developed deficits in performance of delayed matching-to-sample, visual pattern discrimination reversal, and object retrieval tasks, all tasks that rely upon the integrity of the frontal-striatal axis. Performance on a visual pattern discrimination task, that relies primarily on inferotemporal cortex function, remained intact. These results extend previous findings of frontal-like cognitive deficits in MPTP-treated monkeys and further support the use of this model for studying the pathophysiology of the cognitive deficits associated with parkinsonism.