Mechanisms of Neurogenesis-Mediated Forgetting in the Hippocampus

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The mammalian hippocampus is an area of the brain responsible for learning and memory, and one of the few regions where neurogenesis continues throughout life (Altman, 1962). Neurogenesis in the dentate gyrus (DG) of the hippocampus has a role in many essential learning and memory processes, including forgetting (Akers et al., 2014). This forgetting process is important because it prevents proactive interference between old and new memories (Epp et al., 2016). However, the DG is not typically thought of as the place where new memories are stored; therefore, this process is likely occurring downstream of the DG. While several studies have examined the modulation of neurogenesis in forgetting behaviour, little research has investigated how this process is occurring within the hippocampus. Thus, the main goal of my thesis was to identify subregions of the hippocampus that play a role in this forgetting mechanism by (1) quantifying c-Fos expression in hippocampal subregions and the entorhinal cortex (EC) following a contextual conditioning task in mice and (2) monitoring real-time neuronal activity during the contextual task using fiber photometry. We replicated previous findings by others, confirming that increasing neurogenesis enhances forgetting. We found that voluntary running, to the extent that neurogenesis is increased, results in decreased context memory and decreased activity in CA1 and the supragranular and infragranular layers of the EC.
adult neurogenesis, forgetting, CA1, c-Fos, fiber photometry, hippocampus, memory
Evans, A. (2020). Mechanisms of Neurogenesis-Mediated Forgetting in the Hippocampus (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from