Effects of long-term individual housing of middle-aged female Octodon degus on spatial learning and memory in the Barnes maze task

IntroductionProlonged social isolation is a form of passive chronic stress that has consequences on human and animal behavior. The present study was undertaken to elucidate whether the long-term isolation would precipitate age-related changes in anxiety and spatial learning and memory in degus. MethodsWe investigated the effects of long-term social isolation on anxiety levels in the light-dark test, and spatial orientation abilities in the Barnes maze. Middle-aged female Octodon degus were allocated to either group-housed (3 animals per cage) or individually-housed for 5 months. ResultsUnder this experimental condition, there were no significant group differences in the anxiety level tested in the light-dark test and in the motivation to escape from the Barnes maze. There were no significant differences in cortisol levels between individually- and group-housed animals. On the last acquisition training day of spatial learning, individually- housed animals had a significantly higher number of correct responses and a smaller number of reference and working memory errors than the group-housed animals. In addition, isolated animals showed a tendency for reference and working memory impairment on the retention trial, while group-housed degus showed improvement in these parameters. Discussion and conclusionThe present study indicates that prolonged social isolation during adulthood in female degus has a dual effect on spatial orientation. Specifically, it results in a significant improvement in acquisition skills but a slight impairment in memory retention. The obtained cognitive changes were not accompanied by modification in anxiety and cortisol levels.

Automated summary

The present study aimed to investigate whether prolonged social isolation would precipitate age-related changes in anxiety and spatial learning and memory in degus. The results showed that long-term social isolation did not significantly affect anxiety levels and motivation to escape, but significantly improved spatial learning skills while slightly impairing memory retention. These cognitive changes were not accompanied by modifications in anxiety and cortisol levels.