Title : Why does memory consolidation require sleep?
Abstract:
Non-rapid Eye Movement (NREM) sleep and Rapid Eye Movement (REM) sleep, in both stages, together or individually, helps in memory consolidation. For example, short sleep deprivation (5-6 hours) soon after fear-conditioned training (cued and contextual fear conditioning) and appetitive-conditioned training (trace and delay appetitive conditioning) induced learning deficit in rodents. In addition, NREM sleep significantly increased at a specific window after fear-conditioning, whereas REM sleep significantly increased after learning appetitive-conditioning tasks. Further, we have observed that the changes in sleep architecture are an explicitly consolidation-dependent phenomenon. In addition, we have found that new learning augments sleep-associated brain oscillatory waves during NREM and REM sleep, which plays an essential role in the neural dialogue between circuitries. These findings suggest that sleep is necessary for neural optimization for memory consolidation.
Sleep may help in memory formation at the cellular and system consolidation levels. Short-term total sleep deprivation soon after fear-conditioning alters the expression of some memory candidate genes such as Gsk-3, NCDN, and Shank-3. In addition, short sleep deprivation alters the learning-induced changes in the expression level of protein kinases, cAMP, Arc protein, in the hippocampus. Short-term sleep deprivation soon after training alters the learning-induced increased adult neurogenesis in the dorsal hippocampus. In addition, sleep plays an essential role in inducing synaptic strength. We have shown that the cellular and molecular events involved in the induction of ocular dominance plasticity (ODP) in the visual cortex are triggered by sleep. Sleep consolidates ODP primarily by strengthening the cortical responses to the non-deprived eye through NMDA receptors and the protein kinase-A pathway. Consolidation is also associated with sleep-dependent increases in the activity of remodeling neurons and the phosphorylation of proteins required to potentiate glutamatergic synapses. Our findings demonstrate that sleep possibly helps in memory formation at cellular and systems consolidation levels.
Audience Take Away Notes:
- Sleep is necessary for neural optimization for memory consolidation.
- Sleep possibly helps in memory formation at cellular and systems consolidation levels.
- New learning always augments sleep-associated brain oscillatory waves during sleep, which plays an essential role in the neural dialogue between circuitries.
Acknowledgment: Funding to SKJ from DBT, DST, DST (PURSE), UGC-RNW, UGC-CAS, UPOE-II is highly acknowledged.
