Research press release


Nature Neuroscience

Strengthening memories during sleep

新しく学習した記憶を睡眠中に再活性化することによって、記憶痕跡が強化されることがNature Neuroscience(電子版)の論文で報告されている。この発見は、心的外傷後ストレス症候群などの疾患の治療に臨床的意義をもつ。


B Raschらは、被験者にグリッド内の物体の位置を覚える空間記憶課題を行わせ、同時にある匂いを提示した。被験者にこの匂いと物体の関連を記憶させた後、被験者を、睡眠をとるグループと、同じ時間起きたままのグループに分けた。覚醒または徐波睡眠中の被験者に学習課題の匂いを再び提示したところ、おそらく記憶の再活性化が引き起こされたらしい。睡眠中に再活性化が起こると記憶は後でよく定着し、覚醒中だと定着しにくいことがわかった。機能的磁気共鳴画像法(fMRI)も使用し、覚醒中に匂いによって記憶が再活性化すると、睡眠中にみられる脳の活動とは異なるパターンが見られることが示された。


Reactivating newly learned memories during sleep can strengthen the memory trace, reports a study published online this week in Nature Neuroscience. These findings could have clinical implications for treating disorders such as post-traumatic stress syndromes.

Previous studies have shown that reactivating newly formed memories during a wakeful period soon after learning can actually destabilize the memory trace, making such memories less robust.

Bjorn Rasch and colleagues trained subjects in a spatial memory task, where they had to learn an object location in a grid, while an odor was concurrently presented. After participants formed a memory of this odor-object association, one group of subjects slept while another group stayed awake for a comparable time period. During this period of wakefulness or slow-wave sleep, the odor from the learning task was presented again to the subjects, which presumably triggered a reactivation of the memory. The authors found that reactivation during sleep improved memory retention later on, whereas reactivation when awake impaired it.? The scientists also performed functional magnetic resonance imaging (fMRI) to show that memory reactivation via odor presentation during wakeful periods involved different patterns of brain activity than that seen during sleep.

This finding suggests that memory reactivation can have opposing effects on memory presentation depending on whether the reactivation was done during sleep or when awake.

doi: 10.1038/nn.2744


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