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den Bakker H, Sidorov MS, Fan Z, Lee DJ, Bird LM, Chu CJ, Philpot BD. Abnormal coherence and sleep composition in children with Angelman syndrome: a retrospective EEG study. Mol Autism 2018. [PMID: 29719672 DOI: 10.1186/s13229-018-0214-8.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Background Angelman syndrome (AS) is a neurodevelopmental disorder characterized by intellectual disability, speech and motor impairments, epilepsy, abnormal sleep, and phenotypic overlap with autism. Individuals with AS display characteristic EEG patterns including high-amplitude rhythmic delta waves. Here, we sought to quantitatively explore EEG architecture in AS beyond known spectral power phenotypes. We were motivated by studies of functional connectivity and sleep spindles in autism to study these EEG readouts in children with AS. Methods We analyzed retrospective wake and sleep EEGs from children with AS (age 4-11) and age-matched neurotypical controls. We assessed long-range and short-range functional connectivity by measuring coherence across multiple frequencies during wake and sleep. We quantified sleep spindles using automated and manual approaches. Results During wakefulness, children with AS showed enhanced long-range EEG coherence across a wide range of frequencies. During sleep, children with AS showed increased long-range EEG coherence specifically in the gamma band. EEGs from children with AS contained fewer sleep spindles, and these spindles were shorter in duration than their neurotypical counterparts. Conclusions We demonstrate two quantitative readouts of dysregulated sleep composition in children with AS-gamma coherence and spindles-and describe how functional connectivity patterns may be disrupted during wakefulness. Quantitative EEG phenotypes have potential as biomarkers and readouts of target engagement for future clinical trials and provide clues into how neural circuits are dysregulated in children with AS.
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Affiliation(s)
- Hanna den Bakker
- 1Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599 USA.,2Carolina Institute for Developmental Disabilities, University of North Carolina, Chapel Hill, NC 27599 USA.,3Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599 USA
| | - Michael S Sidorov
- 1Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599 USA.,2Carolina Institute for Developmental Disabilities, University of North Carolina, Chapel Hill, NC 27599 USA.,3Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599 USA
| | - Zheng Fan
- 4Department of Neurology, University of North Carolina, Chapel Hill, NC 27599 USA
| | - David J Lee
- 5Department of Neurosciences, University of California, San Diego, CA USA
| | - Lynne M Bird
- 6Department of Pediatrics, University of California, San Diego, CA USA.,7Division of Dysmorphology/Genetics, Rady Children's Hospital, San Diego, CA USA
| | - Catherine J Chu
- 8Department of Neurology, Massachusetts General Hospital, Boston, MA 02114 USA.,9Harvard Medical School, Boston, MA 02215 USA
| | - Benjamin D Philpot
- 1Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599 USA.,2Carolina Institute for Developmental Disabilities, University of North Carolina, Chapel Hill, NC 27599 USA.,3Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599 USA
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den Bakker H, Sidorov MS, Fan Z, Lee DJ, Bird LM, Chu CJ, Philpot BD. Abnormal coherence and sleep composition in children with Angelman syndrome: a retrospective EEG study. Mol Autism 2018; 9:32. [PMID: 29719672 PMCID: PMC5924514 DOI: 10.1186/s13229-018-0214-8] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Accepted: 04/11/2018] [Indexed: 12/28/2022] Open
Abstract
Background Angelman syndrome (AS) is a neurodevelopmental disorder characterized by intellectual disability, speech and motor impairments, epilepsy, abnormal sleep, and phenotypic overlap with autism. Individuals with AS display characteristic EEG patterns including high-amplitude rhythmic delta waves. Here, we sought to quantitatively explore EEG architecture in AS beyond known spectral power phenotypes. We were motivated by studies of functional connectivity and sleep spindles in autism to study these EEG readouts in children with AS. Methods We analyzed retrospective wake and sleep EEGs from children with AS (age 4–11) and age-matched neurotypical controls. We assessed long-range and short-range functional connectivity by measuring coherence across multiple frequencies during wake and sleep. We quantified sleep spindles using automated and manual approaches. Results During wakefulness, children with AS showed enhanced long-range EEG coherence across a wide range of frequencies. During sleep, children with AS showed increased long-range EEG coherence specifically in the gamma band. EEGs from children with AS contained fewer sleep spindles, and these spindles were shorter in duration than their neurotypical counterparts. Conclusions We demonstrate two quantitative readouts of dysregulated sleep composition in children with AS—gamma coherence and spindles—and describe how functional connectivity patterns may be disrupted during wakefulness. Quantitative EEG phenotypes have potential as biomarkers and readouts of target engagement for future clinical trials and provide clues into how neural circuits are dysregulated in children with AS. Electronic supplementary material The online version of this article (10.1186/s13229-018-0214-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Hanna den Bakker
- 1Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599 USA.,2Carolina Institute for Developmental Disabilities, University of North Carolina, Chapel Hill, NC 27599 USA.,3Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599 USA
| | - Michael S Sidorov
- 1Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599 USA.,2Carolina Institute for Developmental Disabilities, University of North Carolina, Chapel Hill, NC 27599 USA.,3Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599 USA
| | - Zheng Fan
- 4Department of Neurology, University of North Carolina, Chapel Hill, NC 27599 USA
| | - David J Lee
- 5Department of Neurosciences, University of California, San Diego, CA USA
| | - Lynne M Bird
- 6Department of Pediatrics, University of California, San Diego, CA USA.,7Division of Dysmorphology/Genetics, Rady Children's Hospital, San Diego, CA USA
| | - Catherine J Chu
- 8Department of Neurology, Massachusetts General Hospital, Boston, MA 02114 USA.,9Harvard Medical School, Boston, MA 02215 USA
| | - Benjamin D Philpot
- 1Department of Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599 USA.,2Carolina Institute for Developmental Disabilities, University of North Carolina, Chapel Hill, NC 27599 USA.,3Neuroscience Center, University of North Carolina, Chapel Hill, NC 27599 USA
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Circadian preference towards morningness is associated with lower slow sleep spindle amplitude and intensity in adolescents. Sci Rep 2017; 7:14619. [PMID: 29097698 PMCID: PMC5668430 DOI: 10.1038/s41598-017-13846-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Accepted: 10/02/2017] [Indexed: 12/03/2022] Open
Abstract
Individual circadian preference types and sleep EEG patterns related to spindle characteristics, have both been associated with similar cognitive and mental health phenotypes. However, no previous study has examined whether sleep spindles would differ by circadian preference. Here, we explore if spindle amplitude, density, duration or intensity differ by circadian preference and whether these associations are moderated by spindle location, frequency, and time distribution across the night. The participants (N = 170, 59% girls; mean age = 16.9, SD = 0.1 years) filled in the shortened 6-item Horne-Östberg Morningness-Eveningness Questionnaire. We performed an overnight sleep EEG at the homes of the participants. In linear mixed model analyses, we found statistically significant lower spindle amplitude and intensity in the morning as compared to intermediate (P < 0.001) and evening preference groups (P < 0.01; P > 0.06 for spindle duration and density). Spindle frequency moderated the associations (P < 0.003 for slow (<13 Hz); P > 0.2 for fast (>13 Hz)). Growth curve analyses revealed a distinct time distribution of spindles across the night by the circadian preference: both spindle amplitude and intensity decreased more towards morning in the morning preference group than in other groups. Our results indicate that circadian preference is not only affecting the sleep timing, but also associates with sleep microstructure regarding sleep spindle phenotypes.
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Iotchev IB, Kis A, Bódizs R, van Luijtelaar G, Kubinyi E. EEG Transients in the Sigma Range During non-REM Sleep Predict Learning in Dogs. Sci Rep 2017; 7:12936. [PMID: 29021536 PMCID: PMC5636833 DOI: 10.1038/s41598-017-13278-3] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Accepted: 09/19/2017] [Indexed: 11/09/2022] Open
Abstract
Sleep spindles are phasic bursts of thalamo-cortical activity, visible in the cortex as transient oscillations in the sigma range (usually defined in humans as 12-14 or 9-16 Hz). They have been associated with sleep-dependent memory consolidation and sleep stability in humans and rodents. Occurrence, frequency, amplitude and duration of sleep spindles co-vary with age, sex and psychiatric conditions. Spindle analogue activity in dogs has been qualitatively described, but never quantified and related to function. In the present study we used an adjusted version of a detection method previously validated in children to test whether detections in the dogs show equivalent functional correlates as described in the human literature. We found that the density of EEG transients in the 9-16 Hz range during non-REM sleep relates to memory and is characterized by sexual dimorphism similarly as in humans. The number of transients/minute was larger in the learning condition and for female dogs, and correlated with the increase of performance during recall. It can be concluded that in dogs, automatic detections in the 9-16 Hz range, in particular the slow variant (<13 Hz), are functional analogues of human spindles.
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Affiliation(s)
| | - Anna Kis
- Institute of Cognitive Neuroscience and Psychology, Hungarian Academy of Sciences, Budapest, Hungary
| | - Róbert Bódizs
- Institute of Behavioural Sciences, Semmelweis University, Budapest, Hungary
| | | | - Enikő Kubinyi
- Department of Ethology, Eötvös Loránd University, Budapest, Hungary
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Blaskovich B, Szőllősi Á, Gombos F, Racsmány M, Simor P. The Benefit of Directed Forgetting Persists After a Daytime Nap: The Role of Spindles and Rapid Eye Movement Sleep in the Consolidation of Relevant Memories. Sleep 2017; 40:2732008. [PMID: 28364418 DOI: 10.1093/sleep/zsw076] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Study Objectives We aimed to investigate the effect of directed forgetting instruction on memory retention after a 2-hour delay involving a daytime nap or an equivalent amount of time spent awake. We examined the associations between sleep-specific oscillations and the retention of relevant and irrelevant study materials. Methods We applied a list-method directed forgetting paradigm manipulating the perceived relevance of previously encoded lists of words. Participants were randomly assigned to either a nap or an awake group, and to a remember or a forget subgroup. The remember and the forget subgroups were both instructed to study two consecutive lists of words, although, the forget subgroup was manipulated to forget the first list and memorize only the second one. Participants were 112 healthy individuals (44 men; Mage = 21.4 years, SD = 2.4). Results A significant directed forgetting effect emerged after a 2-hour delay both in the awake and sleep conditions; however, the effect was more pronounced within the sleep group. The benefit of directed forgetting, that is, relatively enhanced recall of relevant words in the forget group, was evidenced only in those participants that reached rapid eye movement (REM) phase. Non-rapid eye movement (NREM) sigma power was correlated with memory performance for the relevant (second) list, and sleep spindle amplitude was associated with the retention of both lists. These associations, however, were detected only within the forget subgroup. REM duration correlated with recall performance for the relevant (second) list within the forget subgroup, and with recall performance for the first list within the remember subgroup. Conclusions A directed forgetting effect persists after a 2-hour delay spent awake or asleep. Spindle-related activity and subsequent REM sleep might selectively facilitate the processing of memories that are considered to be relevant for the future.
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Affiliation(s)
- Borbála Blaskovich
- Department of Cognitive Science, Budapest University of Technology and Economics, Budapest, Hungary
| | - Ágnes Szőllősi
- Department of Cognitive Science, Budapest University of Technology and Economics, Budapest, Hungary
| | - Ferenc Gombos
- Department of General Psychology, Pázmány Péter Catholic University, Budapest, Hungary
| | - Mihály Racsmány
- Department of Cognitive Science, Budapest University of Technology and Economics, Budapest, Hungary
- Frontostriatal System Research Group, Hungarian Academy of Sciences, Budapest, Hungary
| | - Péter Simor
- Department of Cognitive Science, Budapest University of Technology and Economics, Budapest, Hungary
- Nyírő Gyula Hospital, National Institute of Psychiatry and Addictions, Budapest, Hungary
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Cortical dendritic activity correlates with spindle-rich oscillations during sleep in rodents. Nat Commun 2017; 8:684. [PMID: 28947770 PMCID: PMC5612962 DOI: 10.1038/s41467-017-00735-w] [Citation(s) in RCA: 77] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Accepted: 07/21/2017] [Indexed: 12/31/2022] Open
Abstract
How sleep influences brain plasticity is not known. In particular, why certain electroencephalographic (EEG) rhythms are linked to memory consolidation is poorly understood. Calcium activity in dendrites is known to be necessary for structural plasticity changes, but this has never been carefully examined during sleep. Here, we report that calcium activity in populations of neocortical dendrites is increased and synchronised during oscillations in the spindle range in naturally sleeping rodents. Remarkably, the same relationship is not found in cell bodies of the same neurons and throughout the cortical column. Spindles during sleep have been suggested to be important for brain development and plasticity. Our results provide evidence for a physiological link of spindles in the cortex specific to dendrites, the main site of synaptic plasticity. Different stages of sleep, marked by particular electroencephalographic (EEG) signatures, have been linked to memory consolidation, but underlying mechanisms are poorly understood. Here, the authors show that dendritic calcium synchronisation correlates with spindle-rich sleep phases.
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Electrophysiological and microstructural features of sleep in children at high risk for depression: a preliminary study. Sleep Med 2017; 36:95-103. [DOI: 10.1016/j.sleep.2017.05.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2017] [Revised: 05/02/2017] [Accepted: 05/03/2017] [Indexed: 01/29/2023]
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Covassin N, Somers VK. Portable Sleep Monitoring Systems: Broadening the Horizons. J Clin Sleep Med 2017; 13:773-774. [PMID: 28502288 DOI: 10.5664/jcsm.6610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 05/10/2017] [Indexed: 11/13/2022]
Affiliation(s)
- Naima Covassin
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota
| | - Virend K Somers
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota
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Christensen JAE, Nikolic M, Hvidtfelt M, Kornum BR, Jennum P. Sleep spindle density in narcolepsy. Sleep Med 2017; 34:40-49. [DOI: 10.1016/j.sleep.2017.02.022] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 02/03/2017] [Accepted: 02/16/2017] [Indexed: 02/07/2023]
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Abstract
Adverse childhood experiences can deleteriously affect future physical and mental health, increasing risk for many illnesses, including psychiatric problems, sleep disorders, and, according to the present hypothesis, idiopathic nightmares. Much like post-traumatic nightmares, which are triggered by trauma and lead to recurrent emotional dreaming about the trauma, idiopathic nightmares are hypothesized to originate in early adverse experiences that lead in later life to the expression of early memories and emotions in dream content. Accordingly, the objectives of this paper are to (1) review existing literature on sleep, dreaming and nightmares in relation to early adverse experiences, drawing upon both empirical studies of dreaming and nightmares and books and chapters by recognized nightmare experts and (2) propose a new approach to explaining nightmares that is based upon the Stress Acceleration Hypothesis of mental illness. The latter stipulates that susceptibility to mental illness is increased by adversity occurring during a developmentally sensitive window for emotional maturation—the infantile amnesia period—that ends around age 3½. Early adversity accelerates the neural and behavioral maturation of emotional systems governing the expression, learning, and extinction of fear memories and may afford short-term adaptive value. But it also engenders long-term dysfunctional consequences including an increased risk for nightmares. Two mechanisms are proposed: (1) disruption of infantile amnesia allows normally forgotten early childhood memories to influence later emotions, cognitions and behavior, including the common expression of threats in nightmares; (2) alterations of normal emotion regulation processes of both waking and sleep lead to increased fear sensitivity and less effective fear extinction. These changes influence an affect network previously hypothesized to regulate fear extinction during REM sleep, disruption of which leads to nightmares. This network consists of a fear circuit that includes amygdala, hippocampus, and medial prefrontal cortex and whose substantial overlap with the stress acceleration findings allows the latter to be incorporated into a wider, more developmentally coherent framework.
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Affiliation(s)
- Tore Nielsen
- Dream and Nightmare Laboratory, Center for Advanced Research in Sleep Medicine, CIUSSS-NÎM - Hôpital du Sacré-Coeur de Montréal, Montreal, QC, Canada.,Department of Psychiatry, Université de Montreal, Montreal, QC, Canada
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61
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Vallat R, Lajnef T, Eichenlaub JB, Berthomier C, Jerbi K, Morlet D, Ruby PM. Increased Evoked Potentials to Arousing Auditory Stimuli during Sleep: Implication for the Understanding of Dream Recall. Front Hum Neurosci 2017; 11:132. [PMID: 28377708 PMCID: PMC5360011 DOI: 10.3389/fnhum.2017.00132] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 03/07/2017] [Indexed: 11/13/2022] Open
Abstract
High dream recallers (HR) show a larger brain reactivity to auditory stimuli during wakefulness and sleep as compared to low dream recallers (LR) and also more intra-sleep wakefulness (ISW), but no other modification of the sleep macrostructure. To further understand the possible causal link between brain responses, ISW and dream recall, we investigated the sleep microstructure of HR and LR, and tested whether the amplitude of auditory evoked potentials (AEPs) was predictive of arousing reactions during sleep. Participants (18 HR, 18 LR) were presented with sounds during a whole night of sleep in the lab and polysomnographic data were recorded. Sleep microstructure (arousals, rapid eye movements (REMs), muscle twitches (MTs), spindles, KCs) was assessed using visual, semi-automatic and automatic validated methods. AEPs to arousing (awakenings or arousals) and non-arousing stimuli were subsequently computed. No between-group difference in the microstructure of sleep was found. In N2 sleep, auditory arousing stimuli elicited a larger parieto-occipital positivity and an increased late frontal negativity as compared to non-arousing stimuli. As compared to LR, HR showed more arousing stimuli and more long awakenings, regardless of the sleep stage but did not show more numerous or longer arousals. These results suggest that the amplitude of the brain response to stimuli during sleep determine subsequent awakening and that awakening duration (and not arousal) is the critical parameter for dream recall. Notably, our results led us to propose that the minimum necessary duration of an awakening during sleep for a successful encoding of dreams into long-term memory is approximately 2 min.
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Affiliation(s)
- Raphael Vallat
- Brain Dynamics and Cognition Team-Lyon Neuroscience Research Center (CRNL), INSERM U1028, CNRS UMR 5292, Centre Hospitalier Le Vinatier (Bat. 452)Bron, France; Lyon 1 UniversityLyon, France
| | - Tarek Lajnef
- LETI Lab, Sfax National Engineering School, University of SfaxSfax, Tunisia; Department of Psychology, Université de MontréalMontréal, QC, Canada
| | | | | | - Karim Jerbi
- Brain Dynamics and Cognition Team-Lyon Neuroscience Research Center (CRNL), INSERM U1028, CNRS UMR 5292, Centre Hospitalier Le Vinatier (Bat. 452)Bron, France; Department of Psychology, Université de MontréalMontréal, QC, Canada
| | - Dominique Morlet
- Brain Dynamics and Cognition Team-Lyon Neuroscience Research Center (CRNL), INSERM U1028, CNRS UMR 5292, Centre Hospitalier Le Vinatier (Bat. 452)Bron, France; Lyon 1 UniversityLyon, France
| | - Perrine M Ruby
- Brain Dynamics and Cognition Team-Lyon Neuroscience Research Center (CRNL), INSERM U1028, CNRS UMR 5292, Centre Hospitalier Le Vinatier (Bat. 452)Bron, France; Lyon 1 UniversityLyon, France
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