| Abstract No.: | A-C1123 |
| Country: | Canada |
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| Title: | CHRONIC STRESS PRODUCES NON-DELAY DEPENDENT DISRUPTIONS OF PERFORMANCE IN A WORKING MEMORY TEST |
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| Authors/Affiliations: | 1 Patrick Poirier*; 1 Christiane Kalliny; 1 Yukiori Goto;
1 McGill University, Montreal, QC, Canada
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| Content: | Objectives: Stress has been shown to affect dopamine (DA) release in the prefrontal cortex (PFC). However, the impact of stress-induced DA release in the PFC on cognitive processes has not yet been well characterized. In this study, we examined the effects of chronic stress on a working memory task for which DA release in the PFC is suggested to be crucial.
Materials and Methods: A delayed alteration task using T-maze was tested with various delay conditions in male adult rats before and after stress. In each trial, animals had to alternately perform left and right turns, requiring the rats to remember the turn of the previous trial in order to turn correctly. Inter-trial intervals were set to 0 (no delay), 10, and 30 seconds. Chronic stress was given to animals by placing them in plexiglass restrainers for 6 hours a day for 21 days. The behavioural test after stress was given one day after the last exposure to stressor. Control animals received the behavioural test 3 weeks after training without stress.
Results: In the no delay condition, the performance of rats in the task was a mean score of 66.7 ± 2.2% (n=4) correct in the chronic stress group, whereas the performance of control animals was 75.0% (n=1). With 10 second delay, stressed and control rats performed at 62.5 ± 2.6% (n=4) and 75.0 ± 0.5% (n=3), respectively. With 30 second delay, the percentage of correct responses in the task were 70.8 ± 1.5% (n=3) and 79.2% (n=1) for chronic stressed and control animals, respectively. Therefore, after chronic stress exposure, performance of the behavioural task was worsened in all delay conditions compared to control animals.
Conclusion: Chronic stress produced impairment on a working memory task irrespective of delays. These results suggest that the impairment produced by chronic stress is not due to temporal storage of information (i.e. short-term memory), but deficits in retrieval of long-term memory for response strategy (i.e. rules of the task).
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