Rachel Schneider, Brigham Young University
Neuroscience
The ability to create distinct memories for very similar stimuli and events is called pattern separation. Pattern separation is thought to be dependent on neurogenesis (the birth of new neurons) in the dentate gyrus, a subregion of the hippocampus. Neurogenesis is reduced in depression, as is overall memory performance. It has been proposed that depression negatively impacts pattern separation abilities, however a link between depression and performance in pattern separation memory tasks has yet to be identified. Accordingly, we designed a study to investigate the relationship between pattern separation performance and level of depression. Eighty-two participants completed a pattern separation memory test and a set of questionnaires to gauge their level of depression. During the task, participants were presented with 600 images one at a time on a computer screen in a continuous recognition paradigm. Participants were asked to determine whether each image was new, old, or similar. Images seen for the first time during the task qualified as “new”, images that were repeated following a variable delay qualified as “old”, and images that were similar to previously presented stimuli, but not exactly the same, qualified as “similar”. A pattern separation score was calculated based on the proportion of correctly identified similar stimuli. We found a negative correlation between depression scores and pattern separation scores (r(82) = – 0.301, p < 0.01). This relationship held constant even when we controlled for other factors known to affect neurogenesis, such as exercise and anxiety levels. These results provide support for the theory that depression is negatively related to pattern separation performance, possibly due to a decrease in neurogenesis in the hippocampus.