A Ninety-minute Daytime Nap Helps Speed Up Memory Consolidation

If you want to memorize something quickly and improve your learning of ‘how’ to do some tasks- take some time off for a day-time nap, for a recent study has revealed that a ninety minute daytime nap helps accelerating the process of long term memory consolidation.

The results of this study may find future implications in the development of artificial methods to speed up the memory consolidation in adults and to create stable memories in a short time

The study conducted by Prof. Avi Karni and Dr. Maria Korman of the Center for Brain and Behavior Research at the University of Haifa, revealed that a daytime nap changes the course of consolidation in the brain.

The long term or permanent memory in humans is divided into two types of memories: memories of "what" and memories of "how to".

For the study, two groups of participants were made to practice in a repeated motor activity which required them to bring the thumb and a finger together at a specific sequence. The researchers examined the “how" aspect of memory in the participants' ability to perform the task quickly and in the correct sequence.

While it was allowed for one of the groups to take a nap for an hour and a half after learning the task, the other group stayed awake.

In the evening, a marked improvement in the task performance was seen in the group that slept in the afternoon, in comparison to the group that stayed awake, which did not exhibit any improvement.

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However, both the groups were found to be at the same skill level after taking an entire night's sleep.

"This part of the research showed that a daytime nap speeds up performance improvement in the brain. After a night's sleep the two groups were at the same level, but the group that slept in the afternoon improved much faster than the group that stayed awake," said Prof. Karni.

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It was revealed in a second experiment that another aspect of memory consolidation is also accelerated by sleep.

Earlier it was shown that the neural process of "how" memory consolidation is susceptible to interference, 6-8 hours after finishing an effective practice session.

This means that after learning or performing a second, different task, one's brain will not be able to successfully remember the first trained task.

A third group of participants was made to learn a different thumb-to-finger movement sequence two hours after practicing the first task. This task being introduced at the beginning of the 6-8 hour period during which the brain consolidates memories, disturbed the memory consolidation process.

Thus the group failed to show any improvement in their ability to perform the task, neither in the evening nor on the following morning.

However, when a fourth group of participants was allowed a 90 minute nap between learning the first set of movements and the second, not much improvement was observed in the evening, but on the next morning a marked improvement was seen in the performance of the participants, as if there had been no interference at all.

"This part of the study demonstrated, for the first time, that daytime sleep can shorten the time "how to" memory becomes immune to interference and forgetting. Instead of 6-8 hours, the brain consolidated the memory during the 90 minute nap," explained Prof. Karni

She also added that though the study showed that the process of memory consolidation is accelerated during daytime sleep, the mechanism accelerated by the sleep is still not known.

The research was published in the scientific journal Nature Neuroscience.

Source-ANI
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