The presence of home-cage stimuli attenuates spontaneous-alternation deficits in rats with septal lesions

The present experiment examined the effects of the olfactory context on spontaneousalternation performance of young adult, female rats following septal lesions. Separate groups of rats were given either septal lesions (n=24) or control surgery (n=24), and then tested on the 8th postoperative day for spontaneous alternation across three trials. Half of the rats in each surgical group were tested in the presence of home-cage nest shavings located in a tray beneath the apparatus; the other septal and control groups were tested over clean, unsoiled wood shavings. Rats tested in the novel, clean-shavings environment showed the typical perserverative deficits in spontaneous alternation associated with septal lesions. Rats with septal lesions tested in the presence of the familiar olfactory stimuli from the home-litter shavings alternated at rates similar to those of controls. The training context had no effect on the alternation performance of controls. These results were interpreted as indicating that rats with septal lesions are differentially responsive to sensory conditions. In particular, the familiar olfactory stimuli may be especially potent in reducing the "hyperreactivity" resulting from the altered sensory processing following septal lesions. Differential salience of olfactory stimuli following such lesions may be related to reports of shifts in social behavior following disruption of septal functioning.