Effects of methsuximide on schedule-controlled responding in the pigeon.

Acute and chronic effects of methsuximide (25, 50, 75, and 100 mg/kg), a succinimide with anticonvulsant properties, were examined in pigeons responding under a multiple fixed-ratio 50 fixed-interval 90-sec schedule of food delivery. The clearest acute effect of methsuximide was a substantial reduction in response rates under both components of the multiple schedule when the drug was administered at 100 mg/kg. Detailed analysis of the temporal distribution of responding under the fixed-interval failed to reveal rate-dependent drug effects. Tolerance appeared to develop to the effects of methsuximide when the drug was administered chronically.