A new study provides important physical evidence to support the idea that sleep helps cement and strengthen new memories. Published in the journal Science, the study shows sleep after learning causes very specific structural changes in the brain – namely growth of connections between brain cells that help them pass information to each other.
Senior investigator Wen-Biao Gan, professor of neuroscience and physiology at NYU Langone Medical Center in New York, NY, says while we have known for some time that sleep is important for learning and memory, the underlying mechanism has not been clear.
“Here we’ve shown how sleep helps neurons form very specific connections on dendritic branches that may facilitate long-term memory,” he explains, “We also show how different types of learning form synapses on different branches of the same neurons, suggesting that learning causes very specific structural changes in the brain.”
In experiments with mice, he and his team show for the first time that learning and sleep cause physical changes in the motor cortex, a brain region involved with voluntary movements.
While we may appear restful as we slumber, our cells are not. The brain cells that were active taking on new information during waking hours, reactivate during deep sleep or slow-wave sleep – a phase when brain waves slow right down, and rapid eye movement, and dreaming, come to a halt.
For some time now, scientists have believed slow-wave sleep is when we form and recall new memories. But exactly how this happens physically is what this study shows for the first time – using mice genetically modified so a particular protein in their brain cells fluoresces when seen with a laser-scanning microscope.
Using this approach, the team could track the growth of new spines along individual branches of dendrites. A brain cell typically has many thousands of dendrites. These connect to other neurons via synapses and carry information in the form of electrical impulses.
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Source: www.medicalnewstoday.com; Catharine Paddock; June 9, 2014.