Очередное исследование подтвердило, что сон помогает закрепить в памяти полученную за день информацию. Во время сна, наступившего после обучения, в мозге происходят особые структурные изменения, заключающиеся в увеличении количества связей между нервными клетками. В эксперименте с мышами эти изменения были зафиксированы в моторной коре, области мозга, связанной с произвольными движениями.
Исследовались 2 группы мышей. Одних в течение часа учили балансировать на вращающемся стержне, а затем они 7 часов спали. Другие обучались такое же время, но после этого 7 часов бодрствовали.
Используя лазерный сканирующий микроскоп, специалисты смогли проследить образование новых межнейронных связей. У первой группы животных дендриты нейронов образовывали большее количество связей с другими нервными клетками, нежели у второй.
Старший исследователь Dr. Wen-Biao Gan, профессор неврологии и физиологии в Нью-Йоркском Медицинском Центре Лангона, объясняет, что это явление помогает нейронам передавать друг другу информацию и способствует запоминанию. Также он отмечает, что разные типы обучения вызывают усиление передачи импульсов по разным синапсам. То есть, условно говоря, для каждого вида информации (навыка) существуют свои пути запоминания (усвоения).
Источник: JournalScience, № 344 (6188), с. 1173-1178
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Sleep strengthens memory after learning
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. 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.
Mouse brain sprouted new dendritic spines within 6 hours of learning new task
The researchers got the mice to learn to balance on a spin rod. Eventually, the mice learned to balance on the rod as it spun faster and faster.They noted that the mice sprouted new dendritic spines within 6 hours of training on the rod.
They then investigated the effect of sleep. They trained two groups of mice: one group trained on the spinning rod for an hour and then slept for 7 hours, while the other trained for the same time but were kept awake for 7 hours. The mice that did not sleep after training showed significantly less new dendritic spine growth than the mice that slept after learning. The researchers also noticed that different types of growth occurred for different types of learning.
For example, running forward on the spinning rod was followed by dendritic spine growth on one set of branches, while running backwards was followed by growth on another set. The researchers suggest this means learning specific tasks is linked to specific structural changes in the brain.
Disrupting sleep prevents new dendritic spine growth
In a final set of experiments, he and his colleagues show that motor cortex brain cells that are active during wakeful learning reactivate during slow-wave sleep. And disrupting this prevents new dendritic spine growth. They conclude this finding sheds light on «neuronal replay,» where during sleep, the brain «practices» what has been learned during the day and consolidates it by growing specific connections within the motor cortex. The National Institutes of Health and the Whitehall Foundation funded the study.
Статья на английском: http://www.medicalnewstoday.com/articles/277956.php
