Abstract-1
Memories of past events can be recalled long after the event, indicating stability. But new experiences are also integrated into existing memories, indicating plasticity. In the hippocampus, spatial representations are known to remain stable but have also been shown to drift over long periods of time. We hypothesized that experience, more than the passage of time, is the driving force behind representational drift. We compared the within-day stability of place cells’ representations in dorsal CA1 of the hippocampus of mice traversing two similar, familiar tracks for different durations. We found that the more time the animals spent actively traversing the environment, the greater the representational drift, regardless of the total elapsed time between visits. Our results suggest that spatial representation is a dynamic process, related to the ongoing experiences within a specific context, and is related to memory update rather than to passive forgetting.
Dorgham Khatib, Aviv Ratzon,Mariell Sellevoll, Omri Barak,Genela Morris, Dori Derdikman.(2023). Active experience, not time, determines within-day representational drift in dorsal CA1. Neuron, 2023-8. [LINK]
Abstract-2
Hippocampal activity is critical for spatial memory. Within a fixed, familiar environment, hippocampal codes gradually change over timescales of days to weeks—a phenomenon known as representational drift. The passage of time and the amount of experience are two factors that profoundly affect memory. However, thus far, it has remained unclear to what extent these factors drive hippocampal representational drift. Here, we longitudinally recorded large populations of hippocampal neurons in mice while they repeatedly explored two different familiar environments that they visited at different time intervals over weeks. We found that time and experience differentially affected distinct aspects of representational drift: the passage of time drove changes in neuronal activity rates, whereas experience drove changes in the cells’ spatial tuning. Changes in spatial tuning were context specific and largely independent of changes in activity rates. Thus, our results suggest that representational drift is a multi-faceted process governed by distinct neuronal mechanisms.
Nitzan Geva, Daniel Deitch, Alon Rubin,Yaniv Ziv. (2023). Time and experience differentially affect distinct aspects of hippocampal representational drift. Neuron, 2023-8. [LINK]
Speaker: Zhaoyang Yin
Time: 9:00 am, 2023/9/11
Location: CIBR A622
