Open Collections

Wang, Tianxin

University of British Columbia

The physical manifestation of memory is an “engram”, the population of neurons activated during a learning experience and, when reactivated, contributes to the process of memory retrieval and subsequent behaviour. Traditionally, it has been believed that neural representations must remain stable to maintain memories. However, memories are dynamic and recent investigations have revealed that neural representations are more fluid than formerly thought. In the hippocampus, neurons previously recruited during an experience show variation through time, a process called representational drift. Memories are distributed across multiple ensembles throughout the brain, and drift has been observed in various brain regions as well. To better understand the stability of neural representations at a broader network level, we sought to characterize the drift of neuronal representations for two identical experiences in brain regions that are involved in perception and memory, and explore how this corresponds to memory organization processes over time. Behavioural results suggest that animals showed increased fear generalization over time. Of the nine brain regions of interest, the vCA1 was shown to reactivate less over time, whereas the RSC reactivated more at remote timepoints. Significant differences in reactivation were observed between the dDG and vDG. Surprisingly, memory representations at recent and remote timepoints were not context-specific, implicating negative effects of aging on memory reactivation and fear generalization. In sum, our findings stand in support of memories being reorganized through systems consolidation over time, where representations are seen to drift in ways that can be predicted by systems consolidation. Further research is needed to delineate the interplay between age, transgenic mice efficacy, and fear generalization.

Text

2024-04-26

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/88030

Psychology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/