A nap to recap or how reward regulates hippocampal-prefrontal memory networks during daytime sleep in humans

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Abstract

Sleep plays a crucial role in the consolidation of newly acquired memories. Yet, how our brain selects the noteworthy information that will be consolidated during sleep remains largely unknown. Here we show that post-learning sleep favors the selectivity of long-term consolidation: when tested three months after initial encoding, the most important (i.e., rewarded, strongly encoded) memories are better retained, and also remembered with higher subjective confidence. Our brain imaging data reveals that the functional interplay between dopaminergic reward regions, the prefrontal cortex and the hippocampus contributes to the integration of rewarded associative memories. We further show that sleep spindles strengthen memory representations based on reward values, suggesting a privileged replay of information yielding positive outcomes. These findings demonstrate that post-learning sleep determines the neural fate of motivationally-relevant memories and promotes a value-based stratification of long-term memory stores.

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Kinga Igloi

Department of Neuroscience, Faculty of Medicine, University of Geneva, Geneva, Switzerland

For correspondence
kinga.igloi@unige.ch

Competing interests
The authors declare that no competing interests exist.
Giulia Gaggioni

Department of Neuroscience, Faculty of Medicine, University of Geneva, Geneva, Switzerland

Competing interests
The authors declare that no competing interests exist.
Virginie Sterpenich

Department of Neuroscience, Faculty of Medicine, University of Geneva, Geneva, Switzerland

Competing interests
The authors declare that no competing interests exist.
Sophie Schwartz

Department of Neuroscience, Faculty of Medicine, University of Geneva, Geneva, Switzerland

Competing interests
The authors declare that no competing interests exist.

Ethics

Human subjects: All subjects were volunteers, gave written informed consent, consent to publish and received financial compensation for their participation in this study. The study was approved by the Ethics Committee of the Geneva University Hospitals.

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.