The effects of age and sex on pattern separation abilities in Sprague-Dawley rats

Zamani, Elham (2024) The effects of age and sex on pattern separation abilities in Sprague-Dawley rats. Masters thesis, Memorial University of Newfoundland.

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Abstract

Pattern separation, which is important for episodic memory, minimizes the overlap between neural representations of similar experiences. This study explored age and sex differences in pattern separation using male and female rats at two life stages: young (4-5 months) and old (14-15 months). We employed a two-trial spatial Y-maze to assess spatial memory, where rats first explored two open arms (acquisition phase) and then were tested for their preference for a previously unexplored arm (24 h later). At this test, female rats regardless of age traveled greater distances and spent more time in the novel arm location, than male rats. In the spontaneous location recognition (SLR) task, rats were presented with objects at known locations during the sample phase and tested for object location memory after 24 h. Two versions of this test were performed: a Dissimilar SLR (DSLR) test where the location of a familiar object in the test trial varied greatly from the previous location of the object, and a Similar SLR (SSLR) task where the new location of a familiar object differed to a lesser degree from the original location. The DSLR and SSLR tasks were performed first in a circular arena, and again in a square arena. In the DSLR task in the square arena young rats spent a greater percentage of time exploring the familiar object in a new location than their older counterparts, also females showed higher discrimination ratios than males. However, results from the SSLR in the square arena did not reveal significant differences across age or sex in memory retention. Contrasts between circular and square arena performance suggest that task environment may influence memory retention and discrimination. Overall, this study highlights potential age and sex influences in tasks of pattern separation and suggests these influences may vary dependent on task.

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