Exercise increases information content and affects long-term stability of hippocampal place codes

Rechavi, Yoav; Rubin, Alon; Ziv, Yaniv

doi:10.1016/j.celrep.2022.111695

Cited by 12 publications

(11 citation statements)

References 80 publications

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“…In particular, it is not directly related to the elapsed time between two recordings. This is consistent with growing evidence that drift is dependent more on the previous experience than on the elapsed time between different recordings [9,23,31]. This work is also in line with the recent findings showing that fluctuations of excitability can happen for multiple reasons related to experience such as neurogenesis [9,29,32], sleep [33] or increase in dopamine level [34].…”

Section: Discussionsupporting

confidence: 92%

“…This is consistent with growing evidence that drift is dependent more on the previous experience than on the elapsed time between different recordings [9, 23, 31]. This work is also in line with the recent findings showing that fluctuations of excitability can happen for multiple reasons related to experience such as neurogenesis [9, 29, 32], sleep [33] or increase in dopamine level [34]. Overall, our work is a proof of principle which highlights the importance of considering excitability when studying drift, although further work would be needed to test this link experimentally.…”

Section: Discussionsupporting

confidence: 91%

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Drift of neural ensembles driven by slow fluctuations of intrinsic excitability

Delamare

Zaki

Cai

et al. 2023

Preprint

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Representational drift refers to the dynamic nature of neural representations in the brain despite the behavior being seemingly stable. Although drift has been observed in many different brain regions, the mechanisms underlying it are not known. Since intrinsic neural excitability is suggested to play a key role in regulating memory allocation, fluctuations of excitability could bias the reactivation of previously stored memory ensembles and therefore act as a motor for drift. Here, we propose a rate-based plastic recurrent neural network with slow fluctuations of intrinsic excitability. We first show that subsequent reactivations of a neural ensemble can lead to drift of this ensemble. The model predicts that drift is induced by co-activation of previously active neurons along with neurons with high excitability which leads to remodelling of the recurrent weights. Consistent with previous experimental works, the drifting ensemble is informative about its temporal history. Crucially, we show that the gradual nature of the drift is necessary for decoding temporal information from the activity of the ensemble. Finally, we show that the memory is preserved and can be decoded by an output neuron having plastic synapses with the main region.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 91%

Drift of neural ensembles driven by slow fluctuations of intrinsic excitability

Delamare

Zaki

Cai

et al. 2023

Preprint

View full text Add to dashboard Cite

show abstract

“…Interestingly, our results stand in contrast to findings from CA1 28 which suggests that EE's effects on spatial tuning of place cells might be limited to DG/CA3. EE also resulted in increased firing rates in CA3 place cells, consistent with previous reports of enrichment-dependent increases in activity in DG mature granule cells and CA1 place cells 39 . This contrasts with studies showing that increased neurogenesis is typically associated with decreased activity in the DG and CA3 19,[22][23][24][25][26] .…”

Section: Discussionsupporting

confidence: 91%

Increased flexibility of CA3 memory representations following environmental enrichment

Ventura,

Duncan,

Ainge

2023

Preprint

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SummaryEnvironmental enrichment (EE) improves memory, particularly under conditions of high memory interference1–6. Here, we investigate the neural mechanisms facilitating improved memory following EE. Using associative recognition memory tasks that model the automatic and integrative nature of episodic memory, we find that EE-dependent improvements in difficult associative memory discriminations are related to increased adult hippocampal neurogenesis and sparser memory representations across the hippocampus. Additionally, by recording CA3 place cells as enriched and standard-housed rats explored the increasingly distinct shapes of a “morph” box, we report for the first time that EE changes the way CA3 place cells discriminate similar contexts. CA3 place cells of enriched rats show greater spatial tuning, increased firing rates, and enhanced remapping to contextual changes. These findings point to more precise and flexible CA3 memory representations in enriched rats. Increased spatial tuning and flexibility might support the well-established EE-dependent improvements in fine memory discrimination.HighlightsEE improves discrimination of similar associative memoriesEE-dependent memory improvements are related to increased adult neurogenesisEE results in sparser hippocampal activityEE increases spatial tuning, firing and remapping of CA3 place cells

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“…Moreover, we found that spatial information content in CA1 and CA3 place cells increased over the course of familiarization with the environment ( Figure 2 C), validating previous reports of hippocampal coding precision gradually increasing during learning. 32 , 36 , 37 Interestingly, the increase in information over time was greater in CA1, gradually closing the gap on CA3 as the mice became familiar with the environments. Next, we measured the similarity in the activity of all place cells across different positions and running directions by calculating the population vector (PV) correlations between each pair of positions and across both running directions in the track ( Figures 2 D and 2E).…”

Section: Resultsmentioning

confidence: 99%

Exercise increases information content and affects long-term stability of hippocampal place codes

Cited by 12 publications

References 80 publications

Drift of neural ensembles driven by slow fluctuations of intrinsic excitability

Drift of neural ensembles driven by slow fluctuations of intrinsic excitability

Increased flexibility of CA3 memory representations following environmental enrichment

Organization of hippocampal CA3 into correlated cell assemblies supports a stable spatial code

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