Repeated administration of pyrithiamine leads to a proportional increase in the remembered durations of events

Abstract

Twenty rats were trained on a peak-interval (PI) timing procedure with auditory signals. For 10 rats, the time of reinforcement was set at 20 sec; for the remaining rats, the time of reinforcement was set at 50 sec. After seven sessions of baseline training, 4 mg/kg of pyrithiamine (PT) were administered i.p. to half of the rats in each group before each of six test sessions, and physiological saline was administered to the remaining subjects. During testing, the times of the maximum response rates of PI functions for PT-treated rats gradually shifted rightward on the time scale until they occurred approximately 14% later than the times of the maximum response rates of the rats receiving saline injections. This pattern of timing behavior can be interpreted as reflecting an increase in the remembered times of reinforcement associated with a decrease both in the effective levels of acetylcholine and in the speed of memory storage.