On the transience of egocentric working memory: evidence from testing the contribution of limbic brain regions.

Rats trained on a nonmatching-to-turn rule revealed that egocentric working memory is readily disrupted, hard to use, and transient. In Experiment 1, rats failed to acquire the rule in a plus-maze. Experiment 2 used 2 different plus-mazes to remove any intramaze cues. Task acquisition occurred only when rats could use direction cues (i.e., nonegocentric cues). In Experiments 3 and 4, a J maze was used to minimize the retention interval and eliminate handling rats within a trial. All rats acquired the nonmatching rule, although a 3-s retention delay severely impaired performance. Fornix lesions transiently disrupted performance of the J-maze task (Experiments 3 and 4), but neither fornix (Experiment 1) nor retrosplenial (Experiment 2) lesions impaired the plus-maze tasks.