The effects of chlorpromazine and pentobarbital on sustained attention in the rat

Summary

The effects of chlorpromazine and pentobarbital were studied in rats trained on a conditioning schedule designed to measure sustained attention. This schedule is a modification of the continuous performance test used in studies with human subjects. Two independent measures of performance are obtained in this schedule: 1. errors resulting from a failure of the animal to respond to a relatively brief and infrequently appearing visual signal and 2. errors resulting from a response by the animal to an inappropriate but more frequently appearing visual signal. The former type of error is believed to be a measure of sustained attention, while the latter is believed to be a measure of discriminative-associative functioning.

The results indicated that the attentive measure was particularly sensitive to low doses of chlorpromazine (0.25 mg/kg) while pentobarbital did not affect this measure except at relatively high doses (12 mg/kg and above). The reverse results were obtained on the discriminative-associative measure. Chlorpromazine did not affect this measure but it was significantly altered by pentobarbital. These results support the findings in man that chlorpromazine effects are more pronounced on a task requiring a high degree of sustained attention while the effects of subhypnotic doses of the barbiturates are more pronounced on a task requiring a relatively high degree of cognitive ability.