Alterations in learning performance in the seizure-prone baboon: effects of elicited seizures and chronic treatment with diazepam and phenobarbital.

A comparison was made of the effects of chronically administered diazepam and phenobarbital with those of elicited seizures on repeated acquisition learning in 3 prepubertal Papio papio. The learning task required the baboons each day to perform different sequences of lever presses on a three-lever behavior panel. Middle dose levels of both diazepam and phenobarbital were found to improve learning performance relative to base-line control levels, as measured by total errors, efficiency, and time required to complete chains of various lengths to a fixed criterion. The doses were well within therapeutically relevant seizure control and clinical blood level ranges. Higher doses of both drugs generally abolished the performance gains achieved with the lower doses. Seizures elicited twice weekly for 2--3 weeks, or daily for 7 days, induced no overall decrement in performance. Cyclicity in subsequent performance was, however, induced by each individual seizure during the twice weekly seizure period, and learning performance was found to be significantly worse at 42 hr than at 18 hr after each seizure. Implications of these data for acquisition of learning in the epileptic are discussed.