Effects of repeated administration of amphetamine on behavioral vigilance: evidence for "sensitized" attentional impairments.

The effects of repeated intermittent administration of amphetamine (1, 2, 3 mg/kg, i.p.) on the performance of rats in a task designed to assess sustained attention were tested. A substantial increase in the number of false alarms (i.e., "claims" for hits in nonsignal trials) was observed following subsequent administrations of amphetamine. This effect could not be accounted for by drug-induced side or position biases, switching behavior or stereotypy. The effects of repeated amphetamine may model some of the cognitive processes which mediate the attribution of incentive salience to stimuli associated with repeated psychostimulant administration and the development of psychostimulant-induced psychotic symptoms.