Low acetylcholine during early sleep is crucial for motor memory consolidation

Abstract

I investigated a potential relationship between motor memory and acetylcholine activity during early sleep characterized by slow-wave electroencephalographic activity and reduced cholinergic tone. I tested the hypothesis that altering acetylcholine levels during early sleep would disrupt motor memory consolidation. I trained 93 wild-type and 17 transgenic adult mice on motor tasks either rotarod or skilled-forelimb reach. Immediately after training, I either increased or decreased acetylcholine levels in the subsequent post-learning early sleep. Upon retesting performance on motor tasks, I discovered that increasing acetylcholine levels impaired motor memory consolidation while decreasing acetylcholine levels did not have an effect. I also found a larger involvement of muscarinic acetylcholine receptors compared to nicotinic ones for motor memory consolidation. With filming and electrophysiology, I determined that increasing acetylcholine altered sleep structure and reduced slow-wave activity in early sleep. These results suggest that motor memories are consolidated during slow-wave sleep when cholinergic levels are low.