Chronic diazepam administration and appetitive discrimination learning: acquisition versus steady-state performance in pigeons.

Chronic injections of 2 mg/kg diazepam disrupted both steady-state performance and new discrimination learning in pigeons. However, the time course of disruption differed for each of the two tasks, i.e., steady-state performance was briefly disrupted early, whereas acquisition showed a more persistent delayed disruption. The difference was interpreted as resulting from a dual effect of diazepam on behavior. The early performance disruption was thought to reflect a general nonspecific sedative action of the drug, while the delayed disruption of learning was interpreted as the result of diazepam's selective interference with acquisition processes. Some support for rapid adjustment to the sedative effects of diazepam was found, but there was no evidence for the development of physiological tolerance to diazepam-induced acquisition deficits.