Dose-dependent impairment in the performance of a go-no go successive discrimination by chlordiazepoxide

After learning a light-cued, go-no go successive discrimination to criterion, male Sprague-Dawley rats received 0, 5, or 10 mg/kg chlordiazepoxide on six performance sessions, followed by two drug-recovery (saline) sessions. Chlordiazepoxide impaired discrimination performance in a dose-dependent manner, with animals in the 5 mg/kg dose condition demonstrating tolerance to the drug after two performance sessions. The degree of discrimination impairment in both drug dose conditions paralleled an increase in responding during no-go phases of the performance task. These findings are consistent with a "disinhibitory hypothesis" of performance impairment and suggest that CDP-drugged animals have difficulty in withholding incorrect responses.