Forelimb performance by squirrel monkeys (Saimiri sciureus) before and after dorsal column lesions.

Old World monkeys with dorsal column lesions have exhibited slow, inept reaching movements in extrapersonal space under neurological examination. The purpose of the present study was to obtain quantified observations of such performance in similarly prepared squirrel monkeys. Squirrel monkeys with high cervical lesions of the dorsal columns were tested preoperatively and postoperatively. They were compared with sham-operated controls on three tests requiring fast reaching for stationary bait and on one test requiring catching of a falling bait. The experimental animals were impaired relative to the controls postoperatively only on bait catching. Possible reasons for the apparent discrepancy between the forelimb performance of New World monkeys and Old World monkeys are discussed.