Research press release


Nature Neuroscience

Learning while sleeping

人は寝ている間でもまったく新しい記憶を受け入れられるとの新しい研究が、Nature Neuroscience誌に報告されている。睡眠が既存の記憶を強化するという知見はすでにあるが、今回の研究は、人が睡眠中に新しい関連づけをも学習できることを示している。

Anat Arziらは被験者に、ある特定の音といい匂いもしくはいやな匂いとを関連づけるだけで、新しい事象を想起しないようにさせた。すなわち、被験者は寝ている間、さまざまな匂いをかぎ、同時に異なる音が鳴るのを聞いた。匂いのなかには腐りかけた魚のようなきわめていやな匂いもあれば、シャンプーのような心地よいものもあった。これらの匂いや音はいずれも、被験者を目覚めさせるほど強いものではないが、熟睡している最中でも、よい匂いをかいだときに限って、被験者の呼吸が深くなった。学習の後には、まったく匂いがない状況でも、事前によい匂いと組み合わせた音を被験者が聞くと、いやな匂いと組み合わせた音を聞いたときより呼吸が深くなった。



People can acquire completely new memories while they are asleep, reports a new study in Nature Neuroscience. While it is already known that sleep can strengthen existing memories, this work demonstrates that people can also learn a new association during sleep.

Anat Arzi and colleagues required participants not to remember new facts, but simply to form a link between a particular tone and a pleasant or unpleasant smell. While participants slept, they smelt various smells, while simultaneously listening to sounds of different tones. Some of these smells were very unpleasant, such as rotting fish, while others were pleasant, such as shampoo. None of these smells or sounds were strong enough to wake the subjects but the authors noted that even while asleep, they inhaled more deeply only when they smelt a pleasant smell. After learning, they also inhaled more deeply when they heard a tone which was previously paired with a pleasant compared to an unpleasant smell, even when no smells were present.

The next day, when participants were awake, they again heard the tones that had been paired with certain smells. The team observed that even though no actual smells were present, they inhaled more deeply when they heard tones previously paired with the pleasant smells. This happened even though the participants had no conscious recall of the pairing between the smells and tones. The authors conclude that the increase in inhalation to occurring after tones previously paired with pleasant smells suggests that the participants had formed an association between the tone and the smell.

While learning more complex things, such as memorizing facts or learning a new language, may still not be possible during sleep, this study demonstrates that it is possible to acquire a simple association while fast asleep.

doi: 10.1038/nn.3193

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