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Two behavioral phenomena characterize human motor memory consolidation: diminishing susceptibility to interference by a subsequent experience and the emergence of delayed, offline gains in performance. A recent model proposes that the sleep-independent reduction in interference is followed by the sleep-dependent expression of offline gains. Here, using the finger-opposition sequence-learning task, we show that an interference experienced at 2 h, but not 8 h, following the initial training prevented the expression of delayed gains at 24 h post-training. However, a 90-min nap, immediately post-training, markedly reduced the susceptibility to interference, with robust delayed gains expressed overnight, despite interference at 2 h post-training. With no interference, a nap resulted in much earlier expression of delayed gains, within 8 h post-training. These results suggest that the evolution of robustness to interference and the evolution of delayed gains can coincide immediately post-training and that both effects reflect sleep-sensitive processes.

In humans, some evidence suggests that there are two different types of spindles during sleep, which differ by their scalp topography and possibly some aspects of their regulation. To test for the existence of two different spindle types, we characterized the activity associated with slow (11-13 Hz) and fast (13-15 Hz) spindles, identified as discrete events during non-rapid eye movement sleep, in non-sleepdeprived human volunteers, using simultaneous electroencephalography and functional MRI. An activation pattern common to both spindle types involved the thalami, paralimbic areas (anterior cingulate and insular cortices), and superior temporal gyri. No thalamic difference was detected in the direct comparison between slow and fast spindles although some thalamic areas were preferentially activated in relation to either spindle type. Beyond the common activation pattern, the increases in cortical activity differed significantly between the two spindle types. Slow spindles were associated with increased activity in the superior frontal gyrus. In contrast, fast spindles recruited a set of cortical regions involved in sensorimotor processing, as well as the mesial frontal cortex and hippocampus. The recruitment of partially segregated cortical networks for slow and fast spindles further supports the existence of two spindle types during human non-rapid eye movement sleep, with potentially different functional significance.H uman sleep is associated with a profound modification of consciousness and the emergence of distinct sleep oscillations. In the early stages of non-rapid eye movement (NREM) sleep, electroencephalographic recordings show characteristic spindle oscillations. In humans, spindles consist of waxing-and-waning 11-to 15-Hz oscillations, lasting 0.5-3 sec. At the cellular level, spindles are associated with substantial neuronal activity. Spindles arise from cyclic inhibition of thalamo-cortical (TC) neurons by reticular thalamic neurons. Postinihibitory rebound spike bursts in TC cells entrain cortical populations in spindle oscillations (1). These neuronal mechanisms, which involve large TC populations, are thought to shape the processing of information during light NREM sleep and participate in the alteration of consciousness that characterizes this stage of sleep.Little is known on the cerebral correlates of human spindles. Early positron emission tomography studies reported a negative relationship between thalamic cerebral blood flow and the power spectrum in the spindle frequency band (2). However, the low temporal resolution of positron emission tomography did not allow for a fine-grained characterization of the cerebral correlates of human spindles. In addition, two kinds of spindles are described in humans. Slow spindles (Ͻ13 Hz) predominate over frontal, whereas fast spindles (Ͼ13 Hz) prevail over centro-parietal areas. The difference in spindle scalp topography is also reflected by profound functional differences. These two spindling activities differ by their circadian and homeostatic regul...

The estrogen-related receptor ␣ (ERR␣) is an orphan member of the superfamily of nuclear hormone receptors expressed in tissues that preferentially metabolize fatty acids. Despite the molecular characterization of ERR␣ and identification of target genes, determination of its physiological function has been hampered by the lack of a natural ligand. To further understand the in vivo function of ERR␣, we generated and analyzed Estrra-null (ERR␣ ؊/؊ ) mutant mice. Here we show that ERR␣ ؊/؊ mice are viable, fertile and display no gross anatomical alterations, with the exception of reduced body weight and peripheral fat deposits. No significant changes in food consumption and energy expenditure or serum biochemistry parameters were observed in the mutant animals. However, the mutant animals are resistant to a high-fat diet-induced obesity. Importantly, DNA microarray analysis of gene expression in adipose tissue demonstrates altered regulation of several enzymes involved in lipid, eicosanoid, and steroid synthesis, suggesting that the loss of ERR␣ might interfere with other nuclear receptor signaling pathways. In addition, the microarray study shows alteration in the expression of genes regulating adipogenesis as well as energy metabolism. In agreement with these findings, metabolic studies showed reduced lipogenesis in adipose tissues. This study suggests that ERR␣ functions as a metabolic regulator and that the ERR␣ ؊/؊ mice provide a novel model for the investigation of metabolic regulation by nuclear receptors.Nuclear receptors are ligand-regulated transcription factors that control key pathways required for normal development and maintenance of homeostasis throughout life (37). Nuclear receptors now comprise a family of 48 genes in mice and humans that encode structurally and functionally related proteins. However, the existence of fewer than 10 receptors had been predicted by classic physiological and biochemical studies (10). Since the discovery of many nuclear receptors had not been anticipated and thus is not linked to recognized natural ligands, these new gene products were referred to as orphan nuclear receptors. During the last decade, extensive study of this gene family revealed that orphan nuclear receptors control essential developmental and metabolic functions in response to natural ligands as diverse as steroid hormones, retinoic acids, leukotrienes, bile acids, cholesterol metabolites, and long-chain fatty acids (reviewed in references 5, 26, and 48). In addition, orphan nuclear receptors have been shown to react to the presence of exogenous ligands such as pesticides (15, 70), phenobarbital (53, 61), and a wide variety of xenobiotic agents and drugs (2,24,39,55,66,68,69). Gene deletion analyses in mice have been particularly useful to uncover biological functions of orphan nuclear receptors. Nuclear orphan receptors have been shown to participate in the development and/or maintenance of the placenta, somitogenesis, brain, heart, hypothalamus-pituitary axis, immune system, and pathways controlling s...

RBD and REM sleep without atonia are frequent in PD as shown by PSG recordings.

The Canadian Society for Exercise Physiology assembled a Consensus Panel representing national organizations, content experts, methodologists, stakeholders, and end-users and followed an established guideline development procedure to create the Canadian 24-Hour Movement Guidelines for Adults aged 18–64 years and Adults aged 65 years or older: An Integration of Physical Activity, Sedentary Behaviour, and Sleep. These guidelines underscore the importance of movement behaviours across the whole 24-h day. The development process followed the strategy outlined in the Appraisal of Guidelines for Research and Evaluation (AGREE) II instrument. A large body of evidence was used to inform the guidelines including 2 de novo systematic reviews and 4 overviews of reviews examining the relationships among movement behaviours (physical activity, sedentary behaviour, sleep, and all behaviours together) and several health outcomes. Draft guideline recommendations were discussed at a 4-day in-person Consensus Panel meeting. Feedback from stakeholders was obtained by survey (n = 877) and the draft guidelines were revised accordingly. The final guidelines provide evidence-based recommendations for a healthy day (24-h), comprising a combination of sleep, sedentary behaviours, and light-intensity and moderate-to-vigorous-intensity physical activity. Dissemination and implementation efforts with corresponding evaluation plans are in place to help ensure that guideline awareness and use are optimized. Novelty First ever 24-Hour Movement Guidelines for Adults aged 18–64 years and Adults aged 65 years or older with consideration of a balanced approach to physical activity, sedentary behaviour, and sleep Finalizes the suite of 24-Hour Movement Guidelines for Canadians across the lifespan

Slow wave sleep (SWS) is associated with spontaneous brain oscillations that are thought to participate in sleep homeostasis and to support the processing of information related to the experiences of the previous awake period. At the cellular level, during SWS, a slow oscillation (<1 Hz) synchronizes firing patterns in large neuronal populations and is reflected on electroencephalography (EEG) recordings as large-amplitude, low-frequency waves. By using simultaneous EEG and event-related functional magnetic resonance imaging (fMRI), we characterized the transient changes in brain activity consistently associated with slow waves (>140 V) and delta waves (75-140 V) during SWS in 14 non-sleep-deprived normal human volunteers. Significant increases in activity were associated with these waves in several cortical areas, including the inferior frontal, medial prefrontal, precuneus, and posterior cingulate areas. Compared with baseline activity, slow waves are associated with significant activity in the parahippocampal gyrus, cerebellum, and brainstem, whereas delta waves are related to frontal responses. No decrease in activity was observed. This study demonstrates that SWS is not a state of brain quiescence, but rather is an active state during which brain activity is consistently synchronized to the slow oscillation in specific cerebral regions. The partial overlap between the response pattern related to SWS waves and the waking default mode network is consistent with the fascinating hypothesis that brain responses synchronized by the slow oscillation restore microwake-like activity patterns that facilitate neuronal interactions.fMRI ͉ neuroimaging ͉ sleep physiology ͉ slow oscillation D uring the deepest stage of nonrapid eye movement (NREM) sleep, also referred to as slow wave sleep (SWS) in humans (stage 3-4 of sleep), spontaneous brain activity is organized by specific physiological rhythms, the neural correlates of which have been described in animals (1). Unit recordings have shown that neuronal activity during SWS is characterized by a fundamental oscillation of membrane potential. This so-called ''slow oscillation'' (Ͻ1 Hz) is recorded in all major types of neocortical neurons during SWS and is composed of a depolarizing phase, associated with important neuronal firing (''up state''), followed by a hyperpolarizing phase during which cortical neurons remain silent for a few hundred milliseconds (''down state'') (2, 3). The slow oscillation occurs synchronously in large neuronal populations in such a way that it can be reflected on electroencephalography (EEG) recordings as large-amplitude, low-frequency waves (4).Delta rhythm (1-4 Hz) is another characteristic oscillation of NREM sleep. The neural underpinnings of delta rhythm remain uncertain, however. In the dorsal thalamus, a clock-like delta rhythm is generated by the interplay of two intrinsic membrane currents, although another delta rhythm survives complete thalamectomy, suggesting a cortical origin (1).In humans, a slow oscillation was identified on s...

The effects of age and gender on sleep EEG power spectral density were assessed in a group of 100 subjects aged 20 to 60 years. We propose a new statistical strategy (mixed-model using fixed-knot regression splines) to analyze quantitative EEG measures. The effect of gender varied according to frequency, but no interactions emerged between age and gender, suggesting that the aging process does not differentially influence men and women. Women had higher power density than men in delta, theta, low alpha, and high spindle frequency range. The effect of age varied according to frequency and across the night. The decrease in power with age was not restricted to slow-wave activity, but also included theta and sigma activity. With increasing age, the attenuation over the night in power density between 1.25 and 8.00 Hz diminished, and the rise in power between 12.25 and 14.00 Hz across the night decreased. Increasing age was associated with higher power in the beta range. These results suggest that increasing age may be related to an attenuation of homeostatic sleep pressure and to an increase in cortical activation during sleep.