Dataset Information

Hippocampal Reactivation Extends for Several Hours Following Novel Experience.

ABSTRACT: New memories are believed to be consolidated over several hours of post-task sleep. The reactivation or "replay" of hippocampal cell assemblies has been proposed to provide a key mechanism for this process. However, previous studies have indicated that such replay is restricted to the first 10-30 min of post-task sleep, suggesting that it has a limited role in memory consolidation. We performed long-duration recordings in sleeping and behaving male rats and applied methods for evaluating the reactivation of neurons in pairs as well as in larger ensembles while controlling for the continued activation of ensembles already present during pre-task sleep ("preplay"). We found that cell assemblies reactivate for up to 10 h, with a half-maximum timescale of ?6 h, in sleep following novel experience, even when corrected for preplay. We further confirmed similarly prolonged reactivation in post-task sleep of rats in other datasets that used behavior in novel environments. In contrast, we saw limited reactivation in sleep following behavior in familiar environments. Overall, our findings reconcile the duration of replay with the timescale attributed to cellular memory consolidation and provide strong support for an integral role of replay in memory.SIGNIFICANCE STATEMENT Neurons that are active during an experience reactivate again afterward during rest and sleep. This replay of ensembles of neurons has been proposed to help strengthen memories, but it has also been reported that replay occurs only in the first 10-30 min of sleep, suggesting a circumscribed role. We performed long-duration recordings in the hippocampus of rats and found that replay persists for several hours in sleep following novel experience, far beyond the limits found in previous reports based on shorter recordings. These findings reconcile the duration of replay with the hours-long timescales attributed to memory consolidation.

SUBMITTER: Giri B

PROVIDER: S-EPMC6382986 | biostudies-literature | 2019 Jan

REPOSITORIES: biostudies-literature

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Hippocampal Reactivation Extends for Several Hours Following Novel Experience.

Giri Bapun B Miyawaki Hiroyuki H Mizuseki Kenji K Cheng Sen S Diba Kamran K

The Journal of neuroscience : the official journal of the Society for Neuroscience 20181210 5

New memories are believed to be consolidated over several hours of post-task sleep. The reactivation or "replay" of hippocampal cell assemblies has been proposed to provide a key mechanism for this process. However, previous studies have indicated that such replay is restricted to the first 10-30 min of post-task sleep, suggesting that it has a limited role in memory consolidation. We performed long-duration recordings in sleeping and behaving male rats and applied methods for evaluating the rea ...[more]

PMID: 30530857

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Project description:Background: Emerging evidence has integrated short-term exposure to PM1 with children’s morbidity and mortality. Nevertheless, most available studies have been conducted on a daily scale, ignoring the exposure variations over the span of a day. Objective: The main intention of this study was to examine the association between pediatric emergency department visits (PEDVs) and intra-day exposures to PM1 and PM2.5. We also aimed to investigate whether a high PM1/PM2.5 ratio elevated the risk of PEDVs independent from PM2.5 exposure within several hours. Methods: We collected hourly data on aerial PM1 and PM2.5 concentrations, all-cause PEDVs, and meteorological factors from two megacities (i.e., Guangzhou and Shenzhen) in southern China during 2015–2016. Time-stratified case-crossover design and conditional logistic regression analysis were used to assess the associations of PEDVs with exposures to PM1 and PM2.5 at different lag hours. The contribution of PM1 to PM2.5-associated risk was quantified by introducing PM1/PM2.5 ratio as an additional exposure indicator in the analysis adjusting for PM2.5. Subgroup analyses were performed stratified by sex, age, and season. Results: During this study period, 97,508 and 101,639 children were included from Guangzhou and Shenzhen, respectively. PM1 and PM2.5 exposures within several hours were both remarkably related to an increased risk of PEDVs. Risks for PEDVs increased by 3.9% (95% confidence interval [CI]: 2.7–5.0%) in Guangzhou and 3.2% (95% CI: 1.9–4.4%) in Shenzhen for each interquartile range (Guangzhou: 21.4 μg/m3, Shenzhen: 15.9 μg/m3) increase in PM1 at lag 0–3 h, respectively. A high PM1/PM2.5 ratio was substantially correlated with increased PEDVs, with an excess risk of 2.6% (95% CI: 1.2–4.0%) at lag 73–96 h in Guangzhou and 1.2% (95% CI: 0.4–2.0%) at lag 0–3 h in Shenzhen. Stratified analysis showed a clear seasonal pattern in PM-PEDVs relationships, with notably stronger risks in cold months (October to March of the following year) than in warm months (April to September). Conclusions: Exposures to ambient PM1 and PM2.5 within several hours were related to increased PEDVs. A high PM1/PM2.5 ratio may contribute an additional risk independent from the short-term impacts of PM2.5. These findings highlighted the significance of reducing PM1 in minimizing health risks due to PM2.5 exposure in children.

Dataset Information

Hippocampal Reactivation Extends for Several Hours Following Novel Experience.

Publications

Hippocampal Reactivation Extends for Several Hours Following Novel Experience.

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