Developmental analysis of behavioral dysfunction in rats with septal lesions.

Abstract

At 7 days of age, rats received lesions of the septal nuclei or control operations. The rats received 30 hr of training on a schedule that differentially reinforced low rates of responding (DRL 20 sec), 1 hr per day, beginning at either 27 or 96 days of age. At 126 days of age, all subjects received 10 additional training sessions. After operant testing, all subjects were tested on spontaneous alternation, spatial reversal, and passive avoidance. Results indicated that on a DRL 20-sec schedule subjects that received lesions of the septum neonatally and were tested at different ages performed in a similar manner. Approximately 50% of the subjects with lesions of the septal nuclei reached efficiency levels comparable with those of normal controls. When tested for retention, these efficient subjects still performed similarly to normal subjects. Subjects with septal lesions were facilitated in the acquisition of a spatial habit, were deficient in spatial habit reversal, were less likely to demonstrate spontaneous alternation, and were deficient in passive avoidance. It was concluded that neonatal lesions of the septal nuclei produce permanent behavioral impairments on a dirersity of measures and that although juvenile animals with limbic system damage often manifest behaviors different from adult subjects, the difference was not evident during operant testing.