DRL performance of juvenile rats with septal lesions

Abstract

Infant rats received either lesions of the septal nuclei or control operations at 7 days of age. Following weaning at 21 days, the infant rats were trained to leverpress for food. A DRL 20-secschedule was then used, with the rats being tested in either a conventional operant chamber or one which contained wooden balsa blocks. DRL training continued for 40 daily 60-min sessions. The infant rats successfully leverpressed for food. The presence of the wooden blocks facilitated the development of efficient DRL behavior in the rats with septal lesions, but not in the controls. With training, the juvenile rats with septal lesions trained in conventional chambers showed an improvement in their DRL behavior.

Developmental analysis of behavioral dysfunction in rats with septal lesions.

“…Subsequently, approximately 50% of the experimental subjects, regardless of age at testing, showed gradual acquisition of efficient performance habits. This replicates the observations of Gittis and Hothersall (1974). However, since improvement appeared irrespective of the age at training, acquisition of efficient response habits cannot be attributed to response topographies peculiar to juvenile subjects, as suggested in the Gittis and Hothersall article.…”

“…Eckert (Note 1) reported perseverative fixed-ratio responding in juvenile rats with septal lesions but characterized this abnormality as being less marked than the performance of adult subjects reported in the literature (Hothersall, Johnson, & Collen, 1970;Johnson, 1972). Gittis and Hothersall (1974) observed neonatally operated juvenile subjects on a schedule that differentially reinforced low rates of responding (DHL 20 sec). The subjects with septal lesions, when compared with controls, demonstrated inefficient performance, but when they were compared with adult subjects by data gathered in the same laboratory, unusually efficient performance was noted.…”

“…At 23 days of age, the subjects began a 19-hr deprivation regimen which was in effect until the animals were 60 days of age. This schedule has been shown to maintain developing rats at 85% of the previous day's postfeeding weight (Gittis & Hothersall, 1974).…”

Performance of rats on the Maier Three-Table Task following septal lesions occurring 24 hours after birth.

“…Subsequent work showed that rats given septal lesions as early as 1 day after birth exhibited the high response rates and low efficiency on a DRL 20 task that are typical of animals given similar lesions in adulthood. Furthermore, the impaired DRL performance of these animals, when tested in adulthood, was not modified by handling and experience with the DRL task during development (Gittis & Hothersall, 1974;Molino, 1975;Stahl & Ellen, 1977). Johnson et al (1973) suggested that damage to subcortical structures in neonatal rats may remain permanent because the injured areas are "morphologically and functionally mature" at the time of surgery; that is, the neural mechanisms involved in operant behavior had developed prior to the time of the brain injury and were prevented from functioning normally by the lesion.…”

DRL performance, extinction, and secondary reinforcement: Role of appetitive value of food in mice with septal lesions.

“…Training on a DRL schedule prior to lesion production does not diminish the deficit; Pompi (1974) found that when lesions were produced in well-trained subjects via chronically implanted electrodes, the deficit was observed immediately after the ablation. The DRL deficit is also observed when lesion production and training are performed on the juvenile rat (Gittis & Hothersall, 1974).…”