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Language learning efficiency, dreams and REM sleep



As a follow-up from a previous study, four subjects taking a 6-week French language immersion program maintained a dream diary starting 2 weeks before until 2 weeks after the course. They also slept in the laboratory during four series of nights: one before the course, two during the course and one after the course. Confirming previous observations, it was observed that those subjects who made significant progress in French learning, experienced French incorporations into dreams earlier and had more verbal communication in their dreams during the language training than those who made little progress. Combining these results with those of the earlier study revealed significant positive correlations between language learning efficiency and both increases in REM sleep percentages, and verbal communication in dreams, as well as a negative correlation with latency to the first French incorporation in dreams. These results support the notion that REM sleep and dreaming are related to waking cognitive processes.
International Journal of Psychophysiology, 8 (1989) 43-41
PSP 00228
Intensive language learning and increases in rapid eye movement
sleep: evidence of a performance factor
J. De Koninck, D. Lorrain, G. Christ, G. Proulx * and D. Coulombe
School of Psychology, University of Ottawa, Ottawa, Ont. (Canada)
(Accepted 2 August 1988)
Key words: Rapid eye movement sleep; Language learning; Information processing
Ten anglophone students taking a 6-week French immersion course were recorded in the sleep laboratory during 4 consecutive
nights before the course, during the course and after the course. There was a positive and significant (P < 0.05) correlation between
language learning efficiency and increases in the percentage of rapid eye movement (REM) sleep from pre-course to course periods.
This observation suggests that learning performance may be an important factor in the relationship between information processing
and REM sleep
It has long been proposed that rapid eye move-
ment (REM) sleep is involved in some form or
another in information processing and memory
(i.e. Jouvet, 1965; Empson and Clarke, 1970). A
leading notion formulated by Dewan (1970) and
labelled the ‘Programming Hypothesis’, proposes
that REM sleep is a process for setting up, or
programming, and constantly revising functional
structures in the brain, adjusting them to meet the
current needs of the organism. Such a process
would ensure consolidation of learning and pre-
pare for the assimilation of new information. An
alternative model was recently proposed by Crick
and Mitchinson (1983), suggesting that it is during
* Present address: Baycrest Hospital Department of Psy-
chology, North York (Toronto), Ont.. Canada.
Correspondence: J. De Koninck, School of Psychology, Univer-
sity of Ottawa, Ottawa, Ont. Canada, KIN 6N5.
REM sleep that ‘reverse learning’ or the elimina-
tion of problematic information which otherwise
compete with relevant material takes place. One
prediction consistent with both models is that
following intensive learning, organisms should ex-
hibit an increased need for REM sleep.
For more than 15 years, a host of studies have
tested this hypothesis and have been reviewed
periodically along with other predictions relating
REM sleep with information processing (i.e. Fish-
bein and Gutwein, 1977; McGrath and Cohen,
1978; Pearlman, 1979; Smith, 1985). While there
has been overall support, one interesting observa-
tion has emerged. In animals, increases in REM
sleep following learning tasks were related to
learning efficiency (cf. Leconte et al., 1973) and
not simply to the learning effort. Such a phenome-
non was not, however, clearly established in hu-
mans, although observations along those lines have
been made (Mandai et al., 1986: Verschoor and
Holdstock, 1984). We have now gathered data
from subjects involved in intensive language learn-
0167-X760/89/$03.50 0 1989 Elsevier Science Publishers B.V. (Biomedical Division)
ing which provide strong support for a relation-
ship between learning efficiency and increases in
REM sleep in humans.
Subjects and design
Ten subjects, 6 males and 4 females within an
age range from 18 to 28 years, participated in the
experiment. They were registered in a French Im-
mersion course at the University of Ottawa (de-
scribed below). Their first language was English
and their previous French language learning expe-
rience was limited to a secondary school level.
They received $10 for each night spent in the
French immersion course
Every summer, the University of Ottawa offers
a 6-week intensive French immersion course to
anglophone students. In addition to the courses,
students attend evening activities conducted en-
tirely in French. They spend weekdays in campus
residence. Such an environment provides an ideal
way to control learning conditions while maintain-
ing subjects in a ‘real-life’ situation. French pro-
ficiency is measured by a test developed at the
University of Ottawa. It has been used for 10
years and has proven to be a reliable and valid
measure of competence in French. It is adminis-
tered before the course and after the course thus
providing an assessment of learning efficiency.
Design and procedure
The experiment was conducted over 3 summers.
The first summer, 4 subjects were studied, the
second summer 2, and the last 4 during the third
summer. In each case, each subject spent a mini-
mum of 4 consecutive nights in the laboratory on
3 separate occasions (6 subjects were recorded for
two additional nights for dream collection). A
baseline series was run within two weeks before
the course. Subjects returned to the laboratory for
Series 2 within the second or third week of the
course. The last session was run within one month
after the end of the course. In each series, the first
two nights served as adaptation nights with data
collection on nights three and four.
Electrophysiological measures
Standard electrophysiological sleep measures
were recorded (Rechschaffen and Kales, 1968).
EEG was recorded from sites C3 and C4 with a
linked ear reference. EOG and EMG were re-
corded from bipolar montages. Electrode place-
ment followed the standard lo-20 International
system. The same sleep schedules were maintained
from one series of recordings to another. The
reliability of the sleep stage scoring was de-
termined by calculating the percentage of agree-
ment on 30-s sleep epochs from 6 full nights
between our main judge and that of another ‘blind’
judge. Better than 81% agreement was achieved
for all sleep parameters. For statistical analyses,
data for nights 3 and 4 of each series were com-
Table I presents the distribution of sleep stage
percentages in the three conditions. Analyses of
variance revealed no difference for any of the
sleep stages. However, when the learning perfor-
mance of subjects was taken into account, a rela-
tionship between the percentage of REM sleep
and learning efficiency was observed. Table II
presents the detailed results of % REM and French
proficiency test scores for each subject. An analy-
sis of covariance using French improvement scores
(post-course minus pre-course scores) revealed a
significant increase in REM percentage from the
Distribution in mem percentuges of sleep stages ac’mss conditions
(nights 3 and 4 combined)
Wake 2.15 1.38 4.19
Stage 1 7.26 1.49 6.80
Stage 2 45.99 48.13 45.17
Slow wave sleep (3 + 4) 24.51 22.71 23.87
REM sleep 19.67 22.31 22.22
Distributron in sequence of REM percentages before, during and after the immersion course along n,rth scores on the French proficiency
Subjects Pre-course Pre-course
REM % French test Course
REM % Post-course
French test Post-course
1 24.43 II 21.45 85 21.28
2 20.39 46 25.16 55 14.97
3 24.46 38 24.38 41 25.27
4 24.21 36 19.67 36 22.94
5 13.37 56 25.75 69 21.47
6 17.05 48 28.97 66 28.86
7 20.45 25 23.40 46 22.35
8 18.85 68 21.60 78 22.30
9 15.35 20 17.15 35 20.55
10 18.00 63 8.20 67 22.25
pre-courseto the course period (F = 6.83, df = 1,8,
P < 0.03).
This relationship is clearly illustrated in Fig. 1.
This figure presents the distribution of REM per-
centages from pre-course to post-course for all of
the subjects along with their percentages of im-
provement in French proficiency (subjects’ graphs
are presented in order of level of French pro-
ficiency improvement). It can be seen that only
the last 3 subjects, with little (4% or less) or no
improvement in French, did not show increases in
REM % during the course. When only the 7 other
subjects who showed improvements in French were
considered, a repeated measures analysis of vari-
ance revealed a significant difference in REM %
across conditions (means respectively, 18.6, 24.3,
21.7, F,_,, = 4.35, P < 0.04). Trend analyses re-
vealed that the quadratic configuration (inverted
U) was the most significant ( F2,12 = 6.13, P <
0.05). In other words, efficient language learners
exhibited an increase in REM % during the course
and tended to return to baseline levels after the
course. Finally, another way of expressing this
relationship is the observation, for the total sam-
ple, of a significant Pearson product moment cor-
relation coefficient (r = 0.65, df = 8, P < 0.05) be-
tween learning progress and increases in REM %
from pre-course to course periods. However, the
correlation between learning progress and changes
in REM % from course to post-course was positive
but not significant (I = 0.28). An examination of
individual distributions (Fig. 1) suggests that this
is due to the maintenance of high REM % or even
further increases in some subjects (2, 3, 5).
Similar analyses performed on the other sleep
stages did not reveal any significant trend. It
appears then that the influence of intense lan-
guage learning is restricted solely to REM sleep.
Examination of individual records of the 7 sub-
jects who experienced REM % increases suggests
that stage 2 and/or slow wave sleep tended to be
reduced with a greater vulnerability for the latter
(4 subjects). These effects, however, were not sig-
These results are consistent with those obtained
in studies with animals and are a first clear con-
firmation of a performance factor in the relation-
ship between the amount of REM sleep and com-
plex learning. It will be important to further ex-
plore this phenomenon and to determine whether
our results are applicable to other types of human
learning, where performance varies widely be-
tween subjects. Future research may also de-
termine the influence of second language training
on interhemispheric EEG during sleep. There is
some controversy within the asymmetry literature
as to the localization of second languages (Paradis,
1987). Furthermore one theory of interhemi-
spheric relationships during sleep suggests that
REM is associated with greater right activation
while NREM sleep stages are said to involve left
hemisphere activation (Goldstein et al., 1972;
io 1 COKDl~fION
Fig. 1. Distribution of REM percentages for each subject, presented in order of learning progress.
15 -
#6 IS”
I ,l
10 PKE CO~IKSE 1’0.‘; I’
30 1
Broughton, 1975). More recent studies have failed
to support this theory (cf. Armitage et al., 1988).
An evaluation of interhemispheric EEG changes
during French immersion may resolve some of
these controversies.
Supported by a grant from the Natural Scien-
ces and Engineering Research Council of Canada.
Armitage, R., Hoffmann, R., Loewy, D. and Moffit, A. (1988)
Variations in period-analysed EEG asymmetry in REM
and NREM sleep. Psychophysiology, in press.
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Dewan, E.M. (1970) The programming (P) hypothesis for
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Little, Brown and Company, Boston, pp. 295-307.
Empson, J.A.C. and Clarke, P.R.F. (1970) REM and remem-
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It has become clear that sleep after learning has beneficial effects on the later retrieval of newly acquired memories. The neural mechanisms underlying these effects are becoming increasingly clear as well, particularly those of non-REM sleep. However, much is still unknown about the sleep and memory relationship: the sleep state or features of sleep physiology that associate with memory performance often vary by task or experimental design, and the nature of this variability is not entirely clear. This paper describes pertinent features of sleep physiology and provides a detailed review of the scientific literature indicating beneficial effects of post-learning sleep on memory retrieval. This paper additionally introduces a hypothesis which attributes these beneficial effects of post-learning sleep to separable processes of memory reinforcement and memory refinement whereby reinforcement supports one's ability to retrieve a given memory and refinement supports the precision of that memory retrieval in the context of competitive alternatives. It is observed that features of non-REM sleep are involved in a post-learning substantiation of memory representations that benefit memory performance; thus, memory reinforcement is primarily attributed to non-REM sleep. Memory refinement is primarily attributed to REM sleep given evidence of bidirectional synaptic plasticity in REM sleep and findings from studies of selective REM sleep deprivation.
Each night, we cross a bridge that connects the waking and sleeping worlds. We know very little about this bridge (symbolizing the sleep-onset period), as our passage is brief and leaves only a few fragmented memories behind. Moreover, sleep researchers have largely overlooked this twilight period, certainly owing to its ‘in-between’ and fleeting nature. However, upon closer examination, the sleep-onset period appears as a rich and dynamic time during which our body and mind undergo significant changes. Brain activity slows, muscles relax, and reality gradually distorts: dreamlike images begin to dance before the eyelids. In contrast to the research community, many scientists and artists, such as Thomas Edison and Salvador Dali, were fascinated by this rich period, seeing in it great potential, particularly for increasing their creativity. They even devised methods for capturing creative inspirations from this ‘genius gap’ before they vanished into the limbo of sleep. They would take naps while holding an object that dropped noisily as they dozed off, awakening them just in time to record some of their discoveries/ideas. Is there any truth in this seductive story? In other words, is the sleep-onset period conducive to creativity? This question will serve as the central theme of this thesis. Our main hypothesis was that hybrid states, at the borderland between wakefulness and sleep, would promote creativity. We tested this hypothesis by examining both a physiological state in which sleep and wakefulness coexist (the sleep-onset period, specifically the first sleep stage, named N1) and a sleep disorder, narcolepsy, in which the line between the two vigilance states is even finer than usual. We first demonstrated an increased creative potential in patients with narcolepsy, suggesting an (indirect) link between a privileged access to the sleep-onset period (caused by excessive daytime sleepiness) and the gradual development of creativity over time. Second, we found a direct link between the N1 stage and creativity, given that a single minute of N1 was sufficient to triple the probability of discovering a hidden shortcut to solve a task compared to a period of wakefulness. Additionally, this beneficial effect of the N1 stage disappeared when the subjects reached a deeper sleep (N2). We substantiated these results using spectral analyses and discovered an optimal cocktail for creativity (above and beyond sleep stages), consisting of an intermediate level of alpha (a marker of the wake-to-sleep transition) and a low level of delta (which signs sleep depth). We thus unraveled the existence of a ‘creative sweet spot’ within the sleep-onset period. Hitting this zone requires striking a balance between falling asleep easily and sleeping too deeply. Finally, we investigated the relationship between memory and creativity during sleep onset, using a newly-designed task that allowed us to evaluate these two cognitive functions within a single experimental design. Regrettably, the creative task was too difficult (not enough solvers) to assess the link between memory and creative problem-solving. However, we found that subjects who slept exclusively in N1 exhibited a 10% forgetting of previously encoded individual memory traces, whereas subjects who transitioned to the N2 stage showed less forgetting. Intriguingly, these last two studies both show distinct behavioral effects between two seemingly close sleep stages (N1 and N2). These parallel findings may suggest a link between memory processing (and possibly the pruning of irrelevant information) and the N1-induced boost in creativity. But more importantly, they emphasize the importance of distinguishing the N1 and N2 stages in future research, as they appear to have distinct effects on cognition. Overall, our findings indicate that critical cognitive processes occur during sleep onset. Notably, we found that this period constitutes a doorway into creativity, which neuroscientists [...]
Background: Sleep disorders are frequent and early non-motor symptoms of Parkinson's disease (PD). As a consequence of histopathological changes, the regulation of rapid eye movement (REM) sleep is affected in PD causing REM sleep behaviour disorder in about half of the patients. Considering the well-known role of sleep in memory formation processes, our aim was to investigate the relationship between sleep alterations and cognitive performance to elucidate the possible association between sleep, and especially REM sleep changes and cognitive dysfunction in PD. Methods: We investigated 25 PD patients and 20 healthy controls. All participants underwent a 24-hour-long 19-channel polygraphic EEG recording, neurological, neuroimaging and neuropsychological examination. The visually analysed sleep-EEG and neuropsychological data were statistically evaluated. Results: We found significant negative correlation between verbal fluency and REM sleep ratio as well as average REM sleep period duration in the whole sample. The intergroup analysis showed significant decrease of REM and N3, but increase of N2 sleep ratio, and significantly lower scores in the verbal fluency in PD compared to healthy controls. In the PD group we found significant reduction of N3 sleep ratio in patients with REM sleep behaviour disease compared to patients without it. Conclusion: The negative correlation between verbal fluency performance and REM sleep duration suggests the role of decreased REM sleep in cognitive dysfunction in PD. The early involvement of REM sleep regulation with parallel executive dysfunction in PD emphasise the important role of REM sleep deterioration in the neurodegenerative process of PD.
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The notion that self-disorders are at the root of the emergence of schizophrenia rather than a symptom of the disease, is getting more traction in the cognitive sciences. This is in line with philosophical approaches that consider an enactive self, constituted through action and interaction with the environment. We thereby analyze different definitions of the self and evaluate various computational theories lending to these ideas. Bayesian and predictive processing are promising approaches for computational modeling of the “active self”. We evaluate their implementation and challenges in computational psychiatry and cognitive developmental robotics. We describe how and why embodied robotic systems provide a valuable tool in psychiatry to assess, validate, and simulate mechanisms of self-disorders. Specifically, mechanisms involving sensorimotor learning, prediction, and self-other distinction, can be assessed with artificial agents. This link can provide essential insights to the formation of the self and new avenues in the treatment of psychiatric disorders.
EEG and EMG recordings were taken at the same time each day over a 3-h period, and the duration of paradoxical and slow wave sleep noted for each day. After several days, experimental groups underwent two-way shuttlebox avoidance conditioning prior to the daily recording session. Trials were either crowded (70 trials in a single session) or distributed (one 15-trial session each day); in the latter condition, the learning sessions were continued for each rat until asymptote performance was reached. Control groups were tested for the effects of shock and tone stimulation.The control rats showed no significant change in PS duration at any time during the experiment. In the experimental groups there was, by contrast, a significant increase in PS and, in the distributed condition, this increase was related to the degree of learning achieved, but on the fourth day, when performance reached the asymptote PS duration returned to the reference level. The increased duration of PS in the experimental groups was due to an increase in the number of PS phases, the average duration of each phase not showing any change. It should be added that the increases were found only in the first half-hour of sleep; the effect would thus appear to be immediate and short-lasting.
The method of integrative EEG analysis has been used to establish ratios between amplitudes in the left and right cerebral hemispheres during spontaneous sleep in man, in cats and in rabbits. The data indicate that coincident with each occurrence of a shift from a period of slow wave sleep to a period of rapid-eye movement sleep a reversal of the deviations of the individual ratios from the overall mean ratio established for the whole period of recording took place. This indicates a change in interhemispheric amplitude relationships and might be related to the differences in brain function during the two kinds of sleep.
This paper advances the view that during the paradoxical sleep (PS) phase, the brain sets in motion a “chain-of-events” that is necessary for learning ability and that these events are an integral component of memory storage processes. The evidence supporting the position taken in this paper comes from experiments showing that: (1) PS deprivation (PSD), prior to training or immediately thereafter, impairs the formation of a permanent memory trace; (2) prolonged PSD following learning interferes with the state of a consolidated memory trace; (3) in the course of distributed learning, each learning session is followed by a brief augmentation of PS; (4) massed learning, in which registration of a learned response is incomplete, is followed by a protracted augmentation of PS; (5) pharmacological alterations of brain protein synthesis, cholinergic and catecholaminergic neurotransmitter activity are paralleled by the appearance or disappearance of PS periods, with concomitant changes in memory. The accumulated data suggest that the events occurring during the PS phase play an integral part in memory storage processes in two ways: (1) provide conditions which facilitate the conversion of a learned response into a stable long-term memory, and (2) actively maintain the stability of a consolidated memory trace.
This chapter discusses the results of a study that analyzes the nature and mechanisms of paradoxical sleep (P.S.), or rhombencephalic phase of sleep. In this study, both tonic and phasic electroencephalogram (EEG)or peripheral index of P.S. are very different from EEG and behavioral slow sleep. The pontine origin of rapid eye movements and of the phasic ponto-geniculo-occipital activity occurring during P.S. is emphasized. Phylogenetic study shows that slow sleep may be observed in reptiles, birds, and mammals. In contrast, P.S. is not found at all in the tortoise, and is of very short duration in birds (its ratio to the total sleep being only 0.2%). In mammals, this ratio is about 6–30%. Ontogenetic studies in the kitten show that P.S. may appear immediately after wakefulness and constitutes 90% of total sleep during the first days. In chronic pontile animals, with hypothalamic islands, the rhombencephalic phase of sleep, showing all the pontine electrical and behavioral criteria of P.S. in the intact animal, can be completely identified with the latter. Its mean duration (6 min) is analogous to that of the intact animal. No behavioral or EEG index of slow sleep was observed in pontile animals.
Biorythmic variations in consciousness and psychological functions
  • R Armitage
  • R Hoffmann
  • D Loewy
  • A Moffit
Armitage, R., Hoffmann, R., Loewy, D. and Moffit, A. (1988) Variations in period-analysed EEG asymmetry in REM and NREM sleep. Psychophysiology, in press. Broughton, R. (1975) Biorythmic variations in consciousness and psychological functions. Can. Psychol. Reo., 16 (4):
The function of dreams sleep
  • F Crick
  • G Mitchinson
Crick, F. and Mitchinson, G. (1983) The function of dreams sleep. Nature (Lo&), 304: 111-114.
Modifications ajter a Morse L.anguage Learning Session. Paper presented at the 8th European Congress of Sleep Research
  • P Leconte
  • Sleep
Leconte P., REM Sleep Modifications ajter a Morse L.anguage Learning Session. Paper presented at the 8th European Congress of Sleep Research, Szeged, Hungary, September 1986. McGrath, M.J. and Cohen, D.B. (1978) REM sleep facilitation of adaptive waking behavior: a review of the literature.