本文轉(zhuǎn)載自“Nature自然科研”
本周《自然-通訊》發(fā)表的一項(xiàng)研究Formation and suppression of acoustic memories during human sleep顯示,只有在特定睡眠階段才可能形成新的記憶。研究發(fā)現(xiàn),快速眼動(dòng)(REM)睡眠或輕度非快速眼動(dòng)(NREM)睡眠有益于學(xué)習(xí),而深度非快速眼動(dòng)睡眠對(duì)學(xué)習(xí)新知識(shí)的能力具有抑制效果。以上發(fā)現(xiàn)或有助于我們更深入地了解不同睡眠階段的功能。
睡眠時(shí)大腦受重復(fù)噪聲片段所激發(fā)的活動(dòng)。MEP表示受記憶激發(fā)的電位,NREM2: [305, 405] ms; NREM3: [130, 300] ms; REM: [280, 390] ms。Andrillon et al.
過去已有研究考察我們是否能夠在睡眠期間進(jìn)行學(xué)習(xí),結(jié)果各有不同:一部分的答案是肯定的,而另一部分無法提供證據(jù)證明睡眠期間可以形成新的記憶。法國高等師范學(xué)校的Thomas Andrillon及同事認(rèn)為之所以產(chǎn)生這種不一致情況,是因?yàn)椴煌唠A段的腦活動(dòng)類型是不一樣的,這或可以解釋為什么人有時(shí)候可以學(xué)習(xí),有時(shí)候又不可以。
為了檢驗(yàn)這個(gè)假設(shè),作者對(duì)睡眠中的被試的腦活動(dòng)進(jìn)行監(jiān)測,向他們播放不同的聲音片段。等被試醒來之后,測試他們識(shí)別睡眠期間聽到的聲音的能力。在REM睡眠期間聽到聲音片段提升了被試在該測試中的表現(xiàn),而在NREM睡眠期間聽到則產(chǎn)生了相反的效果。通過分析夜間被試對(duì)聲音的響應(yīng),作者能夠證實(shí)REM睡眠期間的學(xué)習(xí)效果。在NREM睡眠期間,他們觀察到輕度NREM睡眠和深度NREM睡眠存在明顯差異,在前一種情況下,學(xué)習(xí)是可能的,而在后一種情況下,學(xué)習(xí)受到抑制。
學(xué)習(xí)指數(shù)與NREM睡眠中慢波功率的動(dòng)態(tài)關(guān)系。Andrillon et al.
綜合而言,以上研究結(jié)果不僅表明人們可以在睡眠期間學(xué)習(xí),而且還有助于了解一般記憶過程以及它們?cè)诓煌唠A段的變化。
Sleep and memory are deeply related, but the nature of the neuroplastic processes induced by sleep remains unclear. Here, we report that memory traces can be both formed or suppressed during sleep, depending on sleep phase. We played samples of acoustic noise to sleeping human listeners. Repeated exposure to a novel noise during Rapid Eye Movements (REM) or light non-REM (NREM) sleep leads to improvements in behavioral performance upon awakening. Strikingly, the same exposure during deep NREM sleep leads to impaired performance upon awakening. Electroencephalographic markers of learning extracted during sleep confirm a dissociation between sleep facilitating memory formation (light NREM and REM sleep) and sleep suppressing learning (deep NREM sleep). We can trace these neural changes back to transient sleep events, such as spindles for memory facilitation and slow waves for suppression. Thus, highly selective memory processes are active during human sleep, with intertwined episodes of facilitative and suppressive plasticity.
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