Department of Psychology, Brain and Mind Institute, Western University, London, ON, N6A 5B7, Canada.
Department of Psychology, Brain and Mind Institute, Western University, London, ON, N6A 5B7, Canada.
Neuropsychologia. 2022 Jan 7;164:108106. doi: 10.1016/j.neuropsychologia.2021.108106. Epub 2021 Dec 3.
In recent years, there has been growing interest and excitement over the newly discovered cognitive capacities of the sleeping brain, including its ability to form novel associations. These recent discoveries raise the possibility that other more sophisticated forms of learning may also be possible during sleep. In the current study, we tested whether sleeping humans are capable of statistical learning - the process of becoming sensitive to repeating, hidden patterns in environmental input, such as embedded words in a continuous stream of speech. Participants' EEG was recorded while they were presented with one of two artificial languages, composed of either trisyllabic or disyllabic nonsense words, during slow-wave sleep. We used an EEG measure of neural entrainment to assess whether participants became sensitive to the repeating regularities during sleep-exposure to the language. We further probed for long-term memory representations by assessing participants' performance on implicit and explicit tests of statistical learning during subsequent wake. In the disyllabic-but not trisyllabic-language condition, participants' neural entrainment to words increased over time, reflecting a gradual gain in sensitivity to the embedded regularities. However, no significant behavioural effects of sleep-exposure were observed after the nap, for either language. Overall, our results indicate that the sleeping brain can detect simple, repeating pairs of syllables, but not more complex triplet regularities. However, the online detection of these regularities does not appear to produce any durable long-term memory traces that persist into wake - at least none that were revealed by our current measures and sample size. Although some perceptual aspects of statistical learning are preserved during sleep, the lack of memory benefits during wake indicates that exposure to a novel language during sleep may have limited practical value.
近年来，人们对睡眠中大脑新发现的认知能力，包括形成新联想的能力，产生了越来越大的兴趣和兴奋。这些最新发现提出了一种可能性，即其他更复杂的学习形式也可能在睡眠中发生。在目前的研究中，我们测试了睡眠中的人类是否能够进行统计学习——即对环境输入中重复、隐藏模式变得敏感的过程，例如在连续的语音流中嵌入单词。参与者在慢波睡眠期间接受两种人工语言中的一种呈现时，记录他们的脑电图。这两种语言由三音节或双音节无意义单词组成。我们使用 EEG 测量神经同步来评估参与者在睡眠暴露过程中对重复规律的敏感性。我们进一步通过评估参与者在随后的清醒状态下进行的统计学习的内隐和外显测试中的表现，来探究长期记忆的表现。在双音节语言而不是三音节语言条件下，参与者对单词的神经同步随着时间的推移而增加，反映出对嵌入规律的敏感性逐渐提高。然而，在小睡后，无论是哪种语言，都没有观察到睡眠暴露的显著行为效应。总的来说，我们的结果表明，睡眠中的大脑可以检测到简单的、重复的双音节对，但不能检测到更复杂的三音节规律。然而，这些规律的在线检测似乎不会产生任何持久的长期记忆痕迹，这些痕迹在清醒时仍然存在——至少我们目前的测量和样本大小没有揭示出这些痕迹。尽管统计学习的某些知觉方面在睡眠中得到保留，但在清醒时缺乏记忆益处表明，在睡眠中接触新语言可能具有有限的实际价值。
