Efficiency of verbal learning during sleep as related to the EEG pattern
Abstract
- 1.
In order to investigate the possibility of learning during sleep while the EEG is monitored, verbal stimuli (unrelated associates) were given to the sleeping subjects without previous instruction.
- 2.
When the learning material was presented to the subject with sleep EEG, and the EEG pattern failed to change into the alpha wave, no learning was established. When the alpha wave pattern was induced by the stimulation, and when the words were repeated to the subject during the appearance of the alpha wave, learning was distinctly observed. The appearance of the alpha waveduring the presentation of verbal stimuli was found to be an indispensable condition for ‘sleep-learning’.
- 3.
Before or after the presentation of learning material the alpha wave sometimes appeared instead of sleep EEG. The appearance of the alpha wave before or after the stimulation neither increased nor decreased the efficiency of learning appreciably.
- 4.
To induce the alpha wave during sleep by the stimulation, it is advisable to start ‘sleep-learning’ in the light sleep stage (ripple, spindle or hump stage). The stimulation must be repeated more than 10 times during this stage to obtain a positive learning effect.
- 5.
The question is raised as to whether the sleep EEG before and after learning might possibly prevent certain inhibitory processes and thereby facilitate ‘sleep-learning’.
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Learning during sleep in humans – A historical review
2023, Sleep Medicine ReviewsSleep helps to consolidate previously acquired memories. Whether new information such as languages and other useful skills can also be learned during sleep has been debated for over a century, however, the sporadic studies' different objectives and varied methodologies make it difficult to draw definitive conclusions. This review provides a comprehensive overview of the history of sleep learning research conducted in humans, from its empirical beginnings in the 1940s to the present day. Synthesizing the findings from 51 research papers, we show that several studies support the notion that simpler forms of learning, such as habituation and conditioning, are possible during sleep. In contrast, the findings for more complex, applied learning (e.g., learning a new language during sleep) are more divergent. While there is often an indication of processing and learning during sleep when looking at neural markers, behavioral evidence for the transfer of new knowledge to wake remains inconclusive. We close by critically examining the limitations and assumptions that have contributed to the discrepancies in the literature and highlight promising new directions in the field.
Sleep, brain activation and cognition
1990, Physiology and BehaviorSome data have shown the presence of time-of-day effects in learning processes. We explore here whether the same phenomenon occurs during the night and how it relates to REM sleep. In an initial apporach to the question, this paper points out the relationships between: 1) REM sleep and brain activation, and 2) REM sleep and information processing. The data are discussed in terms of a REM sleep implication on information processing and we examine the possibility of modifying this processing by acting on REM sleep.
Sleep learning during stage 2 and REM sleep
1979, Biological PsychologyPairs of subjects were presented with a 20-item picture series at bedtime. In the latter part of the night, a tape-recorded series of 10 words, the verbal equivalents of half the original series of pictures, was repeated 10 times during either Stage 2 or REM sleep. Morning recall and recognition for repeated words was found to be facilitated following repetition during Stage 2 sleep, but relatively unaffected following repetition during REM sleep. However, adjusting for recall, the number of additional words elicited through recognition was found to be significantly greater for REM repeated words than for Stage 2 repeated words. It was suggested that retrieval limitations, perhaps as a result of REM state dependency, rather than storage inhibition may be the main locus of the initial recall failure. By comparison, Stage 2 sleep would seem to present both a lower barrier to memory storage and retrieval compatibility with wakefulness.
Memory retention of stimulations during REM and NREM stages of sleep
1977, Electroencephalography and Clinical NeurophysiologyIn 51 normal young female subjects, stimulation by name calling or by intermittent photic stimulation was given during sleep. At different intervals after the stimulation, the subject was awakened and asked if she could recall it. If alpha activity had not been elicited by the stimulus, there was no recall. If the time occupied by alpha activity evoked by the stimulation was more than 30 sec, the stimulus could be recalled after a long period of sleep. When the evoked alpha activity lasted for less than 30 sec and the subject slept again, the longer the evoked alpha activity, the longer the sleeping time span with the memory retention of the preceding stimulation. With equal durations of evoked alpha activity, retention of the stimulus was better when the sleep following was REM stage than when it was NREM stage (stage 2). The results might be explained by the assumption that process of consolidation takes place most rapidly during wakefulness and is inhibited during sleep but to a lesser degree during REM stage than during NREM stage (stage 2).
51 sujets normaux jeunes de sexe féminin, ont été stimulés par appel du nom ou par stimulation photique intermittente au cours du sommeil. Le sujet a été réveillé à différents intervalles après la stimulation, et il lui a été demandé s'il pouvait se la remémorer. Dans les cas où une activité alpha n'est pas provoquée par la stimulation, il n'y a pas de mémorisation. Lorsque le temps occupé par l'activité alpha évoquée par la stimulation est supérieur à 30 sec, le stimulus peut être remémoré après une longue période de sommeil. Dans les cas où l'activité alpha évoquée dure moins de 30 sec et que le sujet se rendort, plus l'activité alpha évoquée est durable, plus long est l'éventail de temps de sommeil avec rétention mnésique de la stimulation précédente. Pour des durées égales d'activité alpha évoquée, la rétention du stimulus est meilleure lorsque le sommeil sonsécutif est constitué par du sommeil paradoxal que lorsqu'il consiste en stade 2 de sommeil lent. Ces résultats peuvent être expliqués par l'hypothèse suivant laquelle le processus de consolidation prend place plus rapidement au cours de l'état de veille et est inhibé au cours du sommeil mais à un moindre degré au cours du sommeil paradoxal qu'au cours du stade 2 du sommeil lent.
Computer analysis of EEG wakefulness-sleep patterns during learning of novel and familiar sentences
1974, Electroencephalography and Clinical NeurophysiologyIn learning experiments novel and familiar sentences were presented acoustically to human subjects during EEG slow wave sleep. Frequency spectra of parieto-occipital and temporo-occipital EEGs were analyzed 25 sec before and 5–30, 30–55 and 55–80 sec after presentation. Statistical comparisons between spectra were performed, using the distribution means. Three qualities of learning were distinguished in tests after the termination of sleep: “spontaneous recall”, “recognition” and “no recall-no recognition”.
The presentation caused EEG activations of different level and durations. The cases of “no recall-no recognition” were associated with the lowest EEG activations. Significantly higher and longer activations were found when learning was successful, indicating a systematic relationship between level of EEG activation after presentation of the material, and quality of learning. Further, for the same quality of learning, significantly higher activations were associated with novel than with familiar learning material.
Thus, the EEG pattern which exists after the input of learning material to the brain reflects the brain functional state whose level (as characterized by EEG wave frequency) and duration (in conjunction with the factors: interference and difficulty of the learning task) determines the possibility of later recall.
Des phrases, les unes nouvelles, les autres déjà familières ont été prononcées devant des sujets humains en sommeil lent. L'analyse EEG a porté sur les tracés pariéto-occipitaux et temporo-occipitaux recueillis 25 sec avant la présentation orale de la phrase puis de 5–30′ sec, de 30–55 sec et de 55–80 sec après celle-ci. Des comparisons statisques entre spectres de fréquence ont été effectuées à partir des moyennes des distributions. Trois qualités de performance d'apprentissage ont été distinguées au cours de tests effectués après le réveil du sujet: “rappel spontané”, “reconnaissance”, “ni rappel, ni reconnaissance”.
Les présentations ont suscité des activations de l'EEG de divers niveaux et de diverses durées. Les cas de non-rappel et de non-reconnaissance étaient associés aux plus faibles activations; des activations significativement plus importantes et plus durables ont accompagné les apprentissages réussis, indiquant ainsi une relation systématique entre le niveau d'activation EEG après présentation du matériel et la qualité de l'apprentissage. En outre, et pour le même niveau d'apprentissage, ces activations furent significativement plus importantes lorsque la phrase était nouvelle, que lorsqu'elle était familière.
Ainsi, le pattern EEG qui fait suite à la présentation d'une tâche à apprende est-il un reflet d'un certain état fonctionnel cérébral dont le niveau (caractérisé par la fréquence d'ondes EEG) et la persistance (compte-tenu d'autres facteurs tels que les interférences et la difficulté de la tâche) déterminent la possibilité d'un rappel ultérieur.
Recent advances in memory consolidation and information processing during sleep
2022, Journal of Sleep Research
A part of this work was presented at the XVth Annual Meeting of the Japan EEG Society (1966).