Learning and memory is enhanced by sleeping. New structural evidence linking sleep to these two aspects has been found by researchers at Langone Medical Center, New York University (NYU). The researchers used mice in their study. It was established that more dendritic spines developed in those mice that slept after learning a particular task. The dendritic spines are important for transmitting information across the synapses in the brain. They develop from the brain cells, linking with other cells in the brain.
Wen-Biao Gan, Skirball Institute of Biomolecular Medicine, NYU, stated that the new knowledge revealed that human beings develop new connections on particular dendritic branches when they learn something new. He explained that dendritic spines are like leaves growing out of a tree on a specific branch as opposed to any other branch; just like leaves sprout out of a particular branch, so do dendritic spines when we gain new knowledge or skills.
In the experiment, two groups of mice were used. Both groups underwent genetic engineering to make the proteins in their neurons glow under a special microscope. This ensured that the dendritic spine growth was observable, owing to the illuminated proteins. The learning setting was like that of learning how a bicycle is ridden in that the learned skill cannot be forgotten. Using a spinning rod with an increasingly fast speed, the mice were taught how to balance the rod, both while running forward and backwards. Increased dendritic spine development was observed upon learning the activity.
Subsequently, one group of the mice was allowed to sleep for 7 hours after learning the task of spinning-rod balancing, while the other group was deprived of sleep for 7 hours after learning the same task for the same span of time. This was done to examine the effects of sleep on dendritic spine development.
The findings of the experiment showed more dendritic spine development in the mice that slept after learning how to balance the spinning rod in comparison to the mice that were kept awake. It was also observed that the spines developed on different branches subject to the specific activity learned; that is, either running forward or backwards. This study was published in the journal Science.
The researchers of the study concluded that sleep is vital in forming and maintaining synapses associated with learning activities on specific branches. These synapses play a crucial role in memory storage.
A couple of other studies have shown a similar relationship in respect to sleep, learning and memory. Sleeping enhances the capacity of working memory, as shown in a study conducted on people by researchers from Michigan State University. This is important for learning, making decisions and solving problems. A similar study at NYU revealed that rats remember a particular smell better when such a smell is administered to them during slow-wave sleep as opposed to when they are awake.
Therefore, sleep plays a major role in memory as well as learning, decision-making and problem-solving.
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