Sleep smart—optimizing sleep for declarative learning and memory

Abstract

The last decade has witnessed a spurt of new publications documenting sleep's essential contribution to the brains ability to form lasting memories. For the declarative memory domain, slow wave sleep (the deepest sleep stage) has the greatest beneficial effect on the consolidation of memories acquired during preceding wakefulness. The finding that newly encoded memories become reactivated during subsequent sleep fostered the idea that reactivation leads to the strengthening and transformation of the memory trace. According to the active system consolidation account, trace reactivation leads to the redistribution of the transient memory representations from the hippocampus to the long-lasting knowledge networks of the cortex. Apart from consolidating previously learned information, sleep also facilitates the encoding of new memories after sleep, which probably relies on the renormalization of synaptic weights during sleep as suggested by the synaptic homeostasis theory. During wakefulness overshooting potentiation causes an imbalance in synaptic weights that is countered by synaptic downscaling during subsequent sleep. This review briefly introduces the basic concepts and central findings of the research on sleep and memory, and discusses implications of this lab-based work for everyday applications to make the best possible use of sleep's beneficial effect on learning and memory.

Local Targeted Memory Reactivation in Human Sleep

“…The mechanisms mediating the memory benefits of TMR are not fully established, but may involve sensory-triggered hippocampal reactivation and hippocampal-neocortical dialogue [1,4], as recently reported in rodent studies [47]. Our results support the notion that temporal coupling between sleep spindles and slow wave up-states is a non-invasive proxy for effective sleepdependent memory consolidation [1,5,43,[48][49][50][51]. Going beyond correlative evidence, we find that local TMR causally elicits tighter SW-spindle coupling in the cued hemisphere, highlighting the regional quality of sleep oscillations and their relation to memory consolidation [27,29,30,33,52,53].…”

Shaping memory consolidation via targeted memory reactivation during sleep

“…Moreover, this process is purported to restore neuronal selectivity and the ability to learn new information. Recently, it has been proposed that the two models can be integrated, a viewpoint that suggests that local memory potentiation and global downscaling work synergistically to optimize memory processes.…”

Imbalance between TNFα and progranulin contributes to memory impairment and anxiety in sleep-deprived mice

“…The hippocampus appears to be more vulnerable to S-DEP than other brain areas3. Sleep-deprived mice exhibit memory impairments in hippocampus-dependent tasks, but not in hippocampus-independent tasks4.…”