Effects of phenobarbital, clonazepam, valproic acid, ethosuximide, and phenytoin on the delayed matching-to-sample performance of pigeons.

The effects of phenobarbital, clonazepam, valproic acid, ethosuximide, and phenytoin were examined in pigeons performing under a delayed matching-to-sample procedure. Clonazepam, valproic acid, ethosuximide, and phenytoin typically reduced the rate of responding to the sample stimulus, whereas phenobarbital usually increased response rates at high doses. Phenobarbital, clonazepam, and valproic acid produced generally dose-dependent decreases in accuracy; ethosuximide and phenytoin failed to do so. These results suggest that there are qualitative as well as quantitative differences in the effects of anticonvulsant drugs under the delayed matching-to-sample procedure.