Étude polysomnographique comparative du sommeil d'enfants souffrant du syndrôme de Gilles de la Tourette et de sujets contrôles

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Étude polysomnographique comparative du sommeil d'enfants souffrant du syndrôme de Gilles de la Tourette et de sujets contrôles

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Sonno e funzioni cognitive: ruolo della microstruttura del sonno NREM

STUDY OBJECTIVE: Cyclic Alternating Pattern (CAP) is a fluctuation of the arousal level during NREM sleep and consists of the alternation between two phases: phase A (divided into three subtypes A1, A2, and A3) and phase B. A1 is thought to be generated by the frontal cortex and is characterized by the presence of K complexes or delta bursts; additionally, CAP A1 seems to have a role in the involvement of sleep slow wave activity in cognitive processing. Our hypothesis was that an overall CAP rate would have a negative influence on cognitive performance due to excessive fluctuation of the arousal level during NREM sleep. However, we also predicted that CAP A1 would be positively correlated with cognitive functions, especially those related to frontal lobe functioning. For this reason, the objective of our study was to correlate objective sleep parameters with cognitive behavioral measures in normal healthy adults. METHODS: 8 subjects (4 males; 4 females; mean age 27.75 years, range 2334) were recruited for this study. Two nocturnal polysomnography (night 2 and 3 = N2 and N3) were carried out after a night of adaptation. A series of neuropsychological tests were performed by the subjects in the morning and afternoon of the second day (D2am; D2pm) and in the morning of the third day (D3am). Raw scores from the neuropsychological tests were used as dependent variables in the statistical analysis of the results. RESULTS: We computed a series of partial correlations between sleep microstructure parameters (CAP, A1, A2 and A3 rate) and a number of indices of cognitive functioning. CAP rate was positively correlated with visuospatial working memory (Corsi block test), Trial Making Test Part A (planning and motor sequencing) and the retention of words from the Hopkins Verbal Learning Test (HVLT). Conversely, CAP was negatively correlated with visuospatial fluency (Ruff Figure Fluency Test). CAP A1 were correlated with many of the tests of neuropsychological functioning, such as verbal fluency (as measured by the COWAT), working memory (as measured by the Digit Span – Backward test), and both delay recall and retention of the words from the HVLT. The same parameters were found to be negatively correlated with CAP A2 subtypes. CAP 3 were negatively correlated with the Trial Making Test Parts A and B. DISCUSSION: To our knowledge this is the first study indicating a role of CAP A1 and A2 on behavioral cognitive performance of healthy adults. The results suggest that high rate of CAP A1 might be related to an improvement whereas high rate of CAP A2 to a decline of cognitive functions. Further studies need to be done to better determine the role of the overall CAP rate and CAP A3 on cognitive behavioral performances.

Effects of sleep fragmentation on the arousability to resistive loading in NREM and REM sleep in normal men

STUDY OBJECTIVE: In healthy subjects, arousability to inspiratory resistive loading is greater during rapid eye movement (REM) sleep compared with non-REM (NREM) sleep but is poorest in REM sleep in patients with sleep apnea. We therefore examined the hypothesis that sleep fragmentation impairs arousability, especially from REM sleep. DESIGN: Two blocks of 3 polysomnographies (separated by at least 1 week) were performed randomly. An inspiratory-loaded night followed either 2 undisturbed control nights (LN(C)) or 2 acoustically fragmented nights (LN(F)) SETTING: Sleep laboratory. PARTICIPANTS: Sixteen healthy men aged 20 to 29 years. INTERVENTIONS: In both loaded nights, an inspiratory resistive load was added via a valved facemask every 2 minutes during sleep and turned off either when arousal occurred or after 2 minutes. MEASUREMENTS AND RESULTS: During LN(F), arousability remained significantly greater in REM sleep (71% aroused within 2 minutes) compared with stage 2 (29%) or stage 3/4 (16%) sleep. After sleep fragmentation, arousability was decreased in stage 2 sleep (LN(F): 29%; LN(C): 38%; p < .05) and low in early REM sleep, increasing across the night (p < .01). In stage 3/4 sleep, neither an attenuation nor a change across the night was seen after sleep fragmentation. CONCLUSIONS: Mild sleep fragmentation is already sufficient to attenuate arousability in stage 2 sleep and to decrease arousability in early, compared with late, REM sleep. This means that sleep fragmentation affects the arousal response to increasing resistance and that the effects are different in stage 2 and REM sleep. The biologic reason for this increase in the arousal response in REM sleep across the night is not clear.

CD40 activation induces NREM sleep and modulates genes associated with sleep homeostasis

The T-cell derived cytokine CD40 ligand is overexpressed in patients with autoimmune diseases. Through activation of its receptor, CD40 ligand leads to a tumor necrosis factor (TNF) receptor 1 (TNFR1) dependent impairment of locomotor activity in mice. Here we report that this effect is explained through a promotion of sleep, which was specific to non-rapid eye movement (NREM) sleep while REM sleep was suppressed. The increase in NREM sleep was accompanied by a decrease in EEG delta power during NREM sleep and by a decrease in the expression of transcripts in the cerebral cortex known to be associated with homeostatic sleep drive, such as Homer1a, Early growth response 2, Neuronal pentraxin 2, and Fos-like antigen 2. The effect of CD40 activation was mimicked by peripheral TNF injection and prevented by the TNF blocker etanercept. Our study indicates that sleep-wake dysregulation in autoimmune diseases may result from CD40 induced TNF:TNFR1 mediated alterations of molecular pathways, which regulate sleep-wake behavior.

Lucid dreaming during NREM sleep: Two case reports

Lucid dreams – dreams in which the dreamer is aware that is dreaming – most frequently occur during REM sleep, yet there is some evidence suggesting that lucid dreaming can occur during NREM sleep as well. By conducting a sleep laboratory study on lucid dreams, we found two possible instances of lucidity during NREM sleep which are reported here. While lucid dreaming during NREM sleep seems to be much rarer and more difficult to achieve, it appears to be possible and is most likely to occur during N1 sleep, somewhat less likely during N2 sleep and yet to be observed during N3 sleep. Future studies should explore induction methods, underlying neural mechanisms and perceptual/dream content differences between REM and NREM lucid dreams. Furthermore, a consensus agreement is needed to define what is meant by lucid dreaming and create a vocabulary that is helpful in clarifying variable psychophysiological states that can support self-reflective awareness.

Molecular Pathways of Disturbed Sleep and Depression: Studies on Adenosine and Gene Expression Patterns

Background: Adenosine is a potent sleep-promoting substance, and one of its targets is the basal forebrain. Fairly little is known about its mechanism of action in the basal forebrain and about the receptor subtype mediating its regulating effects on sleep homeostasis. Homeostatic deficiency might be one of the causes of the profoundly disturbed sleep pattern in major depressive disorder, which could explain the reduced amounts of delta-activity-rich stages 3 and 4. Since major depression has a relatively high heritability, and on the other hand adenosine regulates sleep homeostasis and might also be involved in mood modulation, adenosine-related genes should be considered for their possible contribution to a predisposition for depression and disturbed sleep in humans. Depression is a complex disorder likely involving the abnormal functioning of several genes. Novel target genes which could serve as the possible common substrates for depression and comorbid disturbed sleep should be identified. In this way specific brain areas related to sleep regulation should be studied by using animal model of depression which represents more homogenous phenotype as compared to humans. It is also important to study these brain areas during the development of depressive-like features to understand how early changes could facilitate pathophysiological changes in depression. Aims and methods: We aimed to find out whether, in the basal forebrain, adenosine induces recovery non-rapid eye movement (NREM) sleep after prolonged waking through the A1 or/and A2A receptor subtype. A1 and A2A receptor antagonists were perfused into the rat basal forebrain during 3 h of sleep deprivation, and the amount of NREM sleep and delta power during recovery NREM sleep were analyzed. We then explored whether polymorphisms in genes related to the metabolism, transport and signaling of adenosine could predispose to depression accompanied by signs of disturbed sleep. DNA from 1423 individuals representative of the Finnish population and including controls and cases with depression, depression accompanied by early morning awakenings and depression accompanied by fatigue, was used in the study to investigate the possible association between polymorphisms from adenosine-related genes and cases. Finally to find common molecular substrates of depression and disturbed sleep, gene expression changes were investigated in specific brain areas in the rat clomipramine model of depression. We focused on the basal forebrain of 3-week old clomipramine-treated rats which develop depressive-like symptoms later in adulthood and on the hypothalamus of adult female clomipramine-treated rats. Results: Blocking of the A1 receptor during sleep deprivation resulted in a reduction of the recovery NREM sleep amount and delta power, whereas A2A receptor antagonism had no effect. Polymorphisms in adenosine-related genes SLC29A3 (equilibrative nucleoside transporter type 3) in women and SLC28A1 (concentrative nucleoside transporter type 1) in men associated with depression alone as well as when accompanied by early morning awakenings and fatigue. In Study III the basal forebrain of postnatal rats treated with clomipramine displayed disturbances in gamma-aminobutyric acid (GABA) receptor type A signaling, in synaptic transmission and possible epigenetic changes. CREB1 was identified as a common transcription denominator which also mediates epigenetic regulation. In the hypothalamus the major changes included the expression of genes in GABA-A receptor pathway, K+ channel-related, glutamatergic and mitochondrial genes, as well as an overexpression of genes related to RNA and mRNA processing. Conclusions: Adenosine plays an important role in sleep homeostasis by promoting recovery NREM sleep via the A1 receptor subtype in the basal forebrain. Also adenosine levels might contribute to the risk of depression with disturbed sleep, since the genes encoding nucleoside transporters showed the strongest associations with depression alone and when accompanied by signs of disturbed sleep in both women and men. Sleep and mood abnormalities in major depressive disorder could be a consequence of multiple changes at the transcriptional level, GABA-A receptor signaling and synaptic transmission in sleep-related basal forebrain and the hypothalamus.

Effect of colostrum feeding method and presence of dam on the sleep, rest and sucking behaviour of newborn calves

"In rats, sucking milk reduces anxiety and promotes non-rapid eye movement (NREM) sleep, and in calves it induces resting but the effect on sleep is unknown. Here, we investigated how calves' sleep was affected by colostrum feeding methods. Forty-one calves were blocked by birth date and randomly allotted within blocks to the experimental treatments. Calves were housed for four days either with their dam (DAM) or individually with warm colostrum feeding (2 L four times a day) from either a teat bucket (TEAT) or an open bucket (BUCKET). DAM calves suckled their dam freely. Calves' sleeping and sucking behaviour was filmed continuously for 48 h at the ages of two and three days. Behavioural sleep (BS) was defined as calves resting at least 30 s with their head still and raised (non-rapid eye movement) or with their head against their body or the ground (rapid eye movement, REM). Latency from the end of colostrum feeding to the start of BS was recorded. We compared behaviour of TEAT calves with that of DAM and BUCKET calves using mixed models. Milk meal duration was significantly longer for TEAT calves than for BUCKET calves (mean +/- S.E.M.; 8.3 +/- 0.6 min vs. 5.2 +/- 0.6 min), but equal to that of DAM calves. We found no effect of feeding method on the duration of daily BS (12 h 59 min I h 38 min) but we found a tendency for the daily amount of NREM sleep; BUCKET calves had less NREM sleep per day than TEAT calves (6 h 18 min vs. 7 h 48 min, S.E.M. = 45 min) and also longer latencies from milk ingestion to BS (21.9 +/- 2.0 min vs. 16.2 +/- 2.0 min). DAM calves slept longer bouts than TEAT calves (10.8 +/- 1.0 min vs. 8.3 +/- 1.0 min) and less often (78 +/- 4 vs. 92 +/- 4). Sucking colostrum from a teat bucket compared with drinking from an open"

Characterization of the sleep architecture in two species of fruit bat

Bats (Chiroptera) are the second-most abundant mammalian order in the world, occupying a diverse range of habitats and exhibiting many different life history traits. In order to contribute to this highly underrepresented group we describe the sleep architecture of two species of frugivorous bat, the greater short-nosed fruit bat (Cynopterus sphinx) and the lesser dawn fruit bat (Eonycteris spelaea). Electroencephalogram (EEG) and electromyogram (EMG) data were recorded from multiple individuals (>= 5) by telemetry over a 72-h period in a laboratory setting with light/dark cycles equivalent to those found in the wild. Our results show that over a 24-h period both species spent more time asleep than awake (mean 15 h), less than previous reported for Chiroptera (20 h). C sphinx spent significantly more of its non-rapid eye movement sleep (NREM) and rapid eye movement sleep (REM) quotas during the light phase, while E. spelaea divided its sleep-wake architecture equally between both light and dark phases. Comparing the sleep patterns of the two species found that C. sphinx had significantly fewer NREM and REM episodes than E. spelaea but each episode lasted for a significantly longer period of time. Potential hypotheses to explain the differences in the sleep architecture of C. sphinx with E. spelaea, including risk of predation and social interaction are discussed. (C) 2010 Published by Elsevier B.V.

AuditoI．y eVoked potentials recorded in monkeys with hallucinatory—like benaVlorS lndUCed DV brom0CnDnne

澳隐亭及多巴胺受体D2激动剂会影响除人以外其它灵长类动物的一系列行为，特别是与运动和 心理活动相关的行为，比如动物会表现出抑制性行为及幻觉样行为。除药物外，快速眼动睡眠(REM)机制的紊 乱也可导致幻觉。打乱清醒、REM及非快速眼动睡眠(NREM)的规律可引起一系列精神病症状。方法当动物 处于清醒，NREM和REM及药物导致的类精神病状态时，同时记录五个皮层脑区的听觉诱发电位，从而研究 对比不同状态下听觉诱发电位的变化。结果在幻觉状态及REM期，前额叶背外侧皮层记录到的潜伏期为250 ms的诱发电位成分出现波峰到基线的相位翻转(PBA250)，说明幻觉状态及REM在前额叶背外侧皮层有类似的调 节机制。结论在前额叶背外侧皮层记录到的N250可以用来判断幻觉样行为是否出现，这表明前额叶背外侧皮 层可能同幻觉样行为最相关。

Ecology and neurophysiology of sleep in two wild sloth species

Study Objectives: Interspecific variation in sleep measured in captivity correlates with various physiological and environmental factors, including estimates of predation risk in the wild. However, it remains unclear whether prior comparative studies have been confounded by the captive recording environment. Herein we examine the impact of predation pressure on sleep in sloths living in the wild. Design: Comparison of two closely related sloth species, one exposed to predation and one free from predation. Setting: Panamanian mainland rainforest (predators present) and island mangrove (predators absent). Participants: Mainland (Bradypus variegatus, 5 males and 4 females) and island (Bradypus pygmaeus, 6 males) sloths. Interventions: None. Measurements and Results: EEG and EMG activity were recorded using a miniature data logger. Although both species spent between 9 and 10 hours per day sleeping, the mainland sloths showed a preference for sleeping at night, whereas island sloths showed no preference for sleeping during the day or night. EEG activity during NREM sleep showed lower low-frequency power, and increased spindle and higher frequency power in island sloths when compared to mainland sloths. Conclusions: In sloths sleeping in the wild, predation pressure influenced the timing of sleep, but not the amount of time spent asleep. The preference for sleeping at night in mainland sloths may be a strategy to avoid detection by nocturnal cats. The pronounced differences in the NREM sleep EEG spectrum remain unexplained, but might be related to genetic or environmental factors.

The Role of Sleep in the Selective Reconsolidation of Declarative Memories

While sleep has been shown to be involved in memory consolidation and the selective enhancement of newly acquired memories of future relevance (Wilhelm, et al., 2011), limited research has investigated the role of sleep or future relevance in processes of memory reconsolidation. The current research employed a list-method directed forgetting procedure in which participants learned two lists of syllable pairs on Night 1 and received directed forgetting instructions on Night 2. On Night 2, one group (Labile; n = 15) received a memory reactivation treatment consisting of reminders designed to return memories of the learned lists to a labile state. A second group (Stable, n = 16) received similar reminders designed to leave memories of the learned lists in their stable state. No differences in forgetting were found across the two lists or groups. However, a negative correlation between frontal delta (1 – 4 Hz) electroencephalographic (EEG) power during Early Stage 2 non-rapid eye movement (NREM) sleep and forgetting of to-beremembered material was found exclusively in the Labile group (r = -.61, p < .05). Further, central theta (4 – 8 Hz ) EEG power during rapid eye movement (REM) sleep was found to correlate with directed forgetting exclusively in the Labile group (r = .81, p < .001) and total forgetting in the Stable group (r = .50, p < .05). These observed relationships support the proposed hypothesis suggesting that sleep processes are involved in the reconsolidation of labile memories, and that this reconsolidation may be selective for memories of future relevance. A role for sleep in the beneficial reprocessing of memories through the selective reconsolidation of labile memories in NREM sleep and the weakening of memories in REM sleep is discussed.

Analyse de l’activité en ondes lentes et des oscillations lentes précédant le somnambulisme

Diverses études se sont penchées sur les paramètres EEG du sommeil en ondes lentes, y compris l’activité en ondes lentes en lien avec le somnambulisme, mais les résultats se révèlent inconsistants et contradictoires. Le premier objectif de la présente étude était d’analyser quantitativement l’EEG en sommeil en mesurant les fluctuations de puissance spectrale en delta (1-4 Hz) et delta lent (0.5-1 Hz) avant des épisodes de somnambulisme. Le second était de détecter les oscillations lentes (> 75 μV, fréquence d'environ 0.7-0.8 Hz) et très lentes (> 140 μV, fréquence d'environ 0.7-0.8 Hz) afin d'examiner leur changement d'amplitude et de densité avant de tels épisodes. Suite à une privation de sommeil de 25 heures, les enregistrements polysomnographiques de 22 adultes atteints de somnambulisme ont été scrutés. L’analyse des 200 secondes avant les épisodes révèle que ceux-ci ne sont pas précédés d’une augmentation graduelle de puissance spectrale en delta ni en delta lent, tant sur les dérivations frontale, centrale que pariétale. Toutefois, une hausse statistiquement significative de la densité des oscillations lentes et des oscillations très lentes a été observée au cours des 20 sec immédiatement avant le début des épisodes. Reste à déterminer le rôle exact de ces paramètres de l’EEG en sommeil par rapport à la manifestation et au diagnostic des parasomnies en sommeil lent.

Sleep spindle activity in children with ADHD

Le trouble du déficit de l’attention/hyperactivité (TDA/H) est le désordre du comportement le plus commun chez les enfants. Les études suggèrent qu'un pourcentage élevé d'enfants atteints de TDA/H souffre de problèmes de sommeil et de somnolence diurne. Le mécanisme sous-jacent à ces difficultés demeure inconnu. Plusieurs études ont suggéré que les fuseaux de sommeil jouent un rôle dans les mécanismes de protection du sommeil. L'objectif de cette étude est de comparer les fuseaux lents (11-13 Hz) et rapides (14-15 Hz) chez des enfants atteints du TDA/H et des sujets contrôles. Nous prévoyons que comparativement aux enfants contrôles, les enfants atteints du TDA/H montreront une plus faible densité des fuseaux lents et rapides, et auront des fuseaux plus courts (sec), moins amples (uV) et plus rapides (cycle/sec). Enfin, nous prévoyons que ces effets seront plus prononcés dans les dérivations cérébrales antérieures que dans les dérivations plus postérieures du cerveau. Les enregistrements polysomnographiques (PSG) du sommeil de nuit ont été menés chez 18 enfants diagnostiqués avec le TDA/H et chez 26 sujets témoins âgés entre 7 et 11 ans. Un algorithme automatique a permis de détecter les fuseaux lents et rapides sur les dérivations frontales, centrales, pariétales et occipitales. Les résultats ont montré que, les caractéristiques PSG du sommeil ne différaient pas significativement entre les deux groupes. On ne note aucune différence significative entre les groupes sur nombre/densité des fuseaux lents et rapides ainsi que sur leurs caractéristiques respectives. Cette étude suggère que les mécanismes de synchronisation du l'EEG en sommeil lent, tel que mesuré par la densité et les caractéristiques des fuseaux lents et rapides en sommeil lent ne différent pas chez les enfants atteints du TDA/H.