The role of sleep in emotional processing: insights and unknowns from rodent research

Abstract

Sleep is essential for the regulation of neural dynamics and animal behavior. In particular, sleep is crucial for memory consolidation and emotional regulation. In turn, emotions are key to the modulation of learning processes, in which sleep also plays a crucial role. Emotional processing triggers coordinated activity between neuronal populations embedded in a network including the hippocampus, amygdala and prefrontal cortex. The optogenetic modulation of these distributed engrams' activity interferes with emotional memory. During non-REM sleep, cross-structure coordinated replay may underpin the consolidation of brain-wide emotional associative engrams. Fear conditioning induces neural synchronization among the amygdala, hippocampus, and medial prefrontal cortex during subsequent REM sleep, the perturbation of which interferes with fear memory consolidation. Future work may focus on the differential mechanisms during REM versus non-REM sleep that underpin emotional regulation and memory consolidation, as well as on distinguishing between these two tightly linked cognitive processes.