ORCID Profile
0000-0001-5311-2370
Current Organisation
Université de Montréal
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Publisher: Frontiers Media SA
Date: 2012
Publisher: Elsevier BV
Date: 03-2010
DOI: 10.1016/J.SLEEP.2009.09.007
Abstract: To examine the associations between habitual sleep duration and intellectual functioning in healthy, well-rested, school-age children. The study group consisted of 39 healthy children, aged 7-11 years old. Nightly actigraphic sleep recordings were taken for four consecutive nights to determine habitual week-night sleep duration in the home environment. Objective measures of cognitive functioning and sleepiness were used to measure daytime functioning. Longer habitual sleep duration in healthy school-age participants was associated with better performance on measures of perceptual reasoning and overall IQ, as measured by the WISC-IV, and on reported measures of competence and academic performance. No association between sleep duration and the studied behavioral measures was found. These findings support the hypothesis that sleep duration is differentially related to some components of cognitive functioning, even in the absence of evidence for sleep deprivation or attention deficits.
Publisher: Wiley
Date: 18-11-2013
DOI: 10.1111/JSR.12108
Abstract: Spindles and slow waves are hallmarks of non-rapid eye movement sleep. Both these oscillations are markers of neuronal plasticity, and play a role in memory and cognition. Normal ageing is associated with spindle and slow wave decline and cognitive changes. The present study aimed to assess whether spindle and slow wave characteristics during a baseline night predict cognitive performance in healthy older adults the next morning. Specifically, we examined performance on tasks measuring selective and sustained visual attention, declarative verbal memory, working memory and verbal fluency. Fifty-eight healthy middle-aged and older adults (aged 50-91 years) without sleep disorders underwent baseline polysomnographic sleep recording followed by neuropsychological assessment the next morning. Spindles and slow waves were detected automatically on artefact-free non-rapid eye movement sleep electroencephalogram. All-night stage N2 spindle density (no./min) and mean frequency (Hz) and all-night non-rapid eye movement sleep slow wave density (no./min) and mean slope (μV/s) were analysed. Pearson's correlations were performed between spindles, slow waves, polysomnography and cognitive performance. Higher spindle density predicted better performance on verbal learning, visual attention and verbal fluency, whereas spindle frequency and slow wave density or slope predicted fewer cognitive performance variables. In addition, rapid eye movement sleep duration was associated with better verbal learning potential. These results suggest that spindle density is a marker of cognitive functioning in older adults and may reflect neuroanatomic integrity. Rapid eye movement sleep may be a marker of age-related changes in acetylcholine transmission, which plays a role in new information encoding.
Publisher: Elsevier BV
Date: 02-2013
DOI: 10.1016/J.NEUROBIOLAGING.2012.05.020
Abstract: Aging induces multiple changes to sleep spindles, which may hinder their alleged functional role in memory and sleep protection mechanisms. Brain aging in specific cortical regions could affect the neural networks underlying spindle generation, yet the topography of these age-related changes is currently unknown. In the present study, we analyzed spindle characteristics in 114 healthy volunteers aged between 20 and 73 years over 5 anteroposterior electroencephalography scalp derivations. Spindle density, litude, and duration were higher in young subjects than in middle-aged and elderly subjects in all derivations, but the topography of age effects differed drastically. Age-related decline in density and litude was more prominent in anterior derivations, whereas duration showed a posterior prominence. Age groups did not differ in all-night spindle frequency for any derivation. These results show that age-related changes in sleep spindles follow distinct topographical patterns that are specific to each spindle characteristic. This topographical specificity may provide a useful biomarker to localize age-sensitive changes in underlying neural systems during normal and pathological aging.
Publisher: Public Library of Science (PLoS)
Date: 13-08-2012
Publisher: Elsevier BV
Date: 02-2011
DOI: 10.1016/J.BBR.2010.10.019
Abstract: This study aimed to determine the distinct contribution of slow (11-13 Hz) and fast (13-15 Hz) spindles in the consolidation process of a motor sequence learning task (MSL). Young subjects (n = 12) were trained on both a finger MSL task and a control (CTRL) condition, which were administered one week apart in a counterbalanced order. Subjects were asked to practice the MSL or CTRL task in the evening (approximately 9:00 p.m.) and their performance was retested on the same task 12h later (approximately 9:00 a.m.). Polysomnographic (PSG) recordings were performed during the night following training on either task, and an automatic algorithm was used to detect fast and slow spindles and to quantify their characteristics (i.e., density, litude, and duration). Statistical analyses revealed higher fast (but not slow) spindle density after training on the MSL than after practice of the CTRL task. The increase in fast spindle density on the MSL task correlated positively with overnight performance gains on the MSL task and with difference in performance gain between the MSL and CTRL tasks. Together, these results suggest that fast sleep spindles help activate the cerebral network involved in overnight MSL consolidation, while slow spindles do not appear to play a role in this mnemonic process.
Publisher: Wiley
Date: 13-01-2011
DOI: 10.1111/J.1460-9568.2010.07543.X
Abstract: Slow waves (SW 75 μV) during non-rapid eye movement (NREM) sleep in humans are characterized by hyperpolarization [surface electroencephalogram (EEG) SW negative phase], during which cortical neurons are silent, and depolarization (surface EEG positive phase), during which the cortical neurons fire intensively. We assessed the effects of age, sex and topography on the dynamics of SW characteristics in a large population (n=87) of healthy young (23.3 ± 2.4 years) and middle-aged (51.9 ± 4.6 years) volunteers. Older subjects showed lower SW density and litude than young subjects. Age-related lower SW density in men was especially marked in prefrontal/frontal brain areas, where they originate more frequently. Older subjects also showed longer SW positive and negative phase durations. These last results indicate that, in young subjects, cortical neurons would synchronously enter the SW hyperpolarization and depolarization phases, whereas this process would take longer in older subjects, leading to lower slope and longer SW positive and negative phases. Importantly, after controlling for SW litude, middle-aged subjects still showed lower slope than young subjects in prefrontal, frontal, parietal and occipital derivations. Age-related effects on SW density, frequency and positive phase duration were more prominent at the beginning of the night, when homeostatic sleep pressure is at its highest. Age-related SW changes may be associated with changes in synaptic density and white matter integrity and may underlie greater sleep fragmentation and difficulty in recuperating and maintaining sleep under challenges in older subjects.
No related grants have been discovered for Julie Carrier.