Wakefulness

Sleep and wakefulness are controlled by specific brain regions. These regions have been identified by classical elimination of brain regions or by acute manipulation of neural activity. However, acute manipulation of these regions often has only a temporary effect on the sleep-wake cycles and chronic inhibition of neural activity in these areas has little effect. These may have been an adaptation and compensation by other brain regions. The preoptic area (POA) has long been recognized as the sleep center first proposed by von Economo. However, a recent optogenetic study found that photostimula

…perceptual experiences compared to wakefulness. Here, we investigated the neural temporal lobe circuits underlying auditory processing during wake and sleep and how sleep physiology affects the processing of auditory stimuli. This was accomplished through the investigation of intracranial electrophysiological responses to pure-tone auditory stimulation (Panel A) in 18 neurosurgical patients with medi

…into long-term memory during wakefulness via processes that preferentially affect nonhippocampal representations. We compared, in rats, the effects of 2-h postencoding periods of sleep and wakefulness on the formation of long-term memory for objects and their associated environmental contexts. We employed a novel-object recognition (NOR) task, using object exploration and exploratory rearing as behavioral indicators of these memories. Remote recall testing (after 1 wk) confirmed significant long-term N

The interaction between sleep function and memory processing is widely observed in both animals and humans, especially in how sleep supports memory consolidation and forgetting. However, whether memory activity during sleep has any regulatory effect on sleep processes is poorly investigated. Here we find that sensory stimuli-triggered emotional memory reactivation significantly affects sleep strategies after learning, as negative memory promotes alertness in sleep while positive memory protects sleep from perturbation. By combining EEG/EMG recording and engram cell activity tracing, our data r

Homeostatic regulation of sleep and wakefulness is essential for survival, but the underlying mechanisms are poorly understood. In Drosophila, a central role in sleep homeostasis is attributed to neurons projecting to the dorsal fan-shaped body (dFB), which store sleep need via their intrinsic excitability. Here, we test if and how dFB neurons incorporate this intrinsic account of sleep drive into their network activity. In vivo dFB neuron ensemble activity is rhythmic, with a peak at 0.2-1 Hz (measured via calcium imaging). The amplitude of these slow oscillations increases with sleep drive,

…levels of consciousness, focusing on wakefulness, anesthesia, and awakening. The data were acquired by two chronically implanted multielectrode arrays (Utah 96), placed in the dorsal prefrontal cortex (dPFC) and dorsal premotor cortex (PMd) of two

Early perspectives on the brain's visual system suggested that it is comprised of separate information streams, each specializing in processing distinct visual features. In this scheme, neurons in lower regions conduct local analyses of image elements within their small receptive fields, while neurons in higher visual areas represent the visual scene in a more global and abstract manner (e.g., by identification and segmentation of objects). However, when processing ambiguous visual stimuli, such as those generated by Kanizsa figures, the local analysis by lower levels might be insufficient for

Paradoxical sleep has been named because it is a state paradoxically close to wakefulness (W) at the cortical level. In this context, our research group has shown using cFos mapping that only a few limbic cortical structures contain activated neurons during PS in contrast with W during which most of the cortical structures are activated. In the present study, we directly determine whether the same or different neurons are activated during W and PS using a new genetic approach. We mapped the neurons activated during W and PS in the transgenic TRAP2-red mouse model. Four male mice implanted wit

Arousal states, such as sleep and wake, are highly correlated with specific rhythmic activity patterns in the neocortex. For example, during sleep, neocortical rhythms are synchronized and dominated by low-frequency oscillations. Recent evidence suggests that inhibitory neurons (INs) are key regulators of neocortical states.Here we investigate how neocortical long-range INs that co-express somatostatin (SST) and neuronal nitric oxide synthase (nNOS) (“SST/nNOS cells”), control patterns of synchronous neocortical activity and arousal states in mice. While the in-vivo function of SST/nNOS cells

…regulation of brain states supporting wakefulness. However, the possibility that it also plays a role for sleep has been around for many years. Gaining a more profound understanding of LC activity in the sleeping brain is crucial for better comprehension of sleep progression in health and disease. Using fiber photometry recordings combined with polysomnography, we show that NREMS alternates between two distinct brain states that arise from infraslow (~50s) activity fluctuations in LC neurons. During NREMS, high LC transie

…syndrome, all leading to increased wakefulness. However, a recent neuropathological study in ALS patients described a loss of orexin-producing neurons, a neuropeptide involved in sleep and metabolic regulation, undermining the idea that sleep alterations are linked to central and peripheral changes. Yet, sleep alterations are poorly characterized in ALS, and their rela

The sympathetic system reacts to affective states, resulting in electrodermal activity (EDA) changes. According to prior research, EDA could be associated with Bipolar Disorder (BD) mood episodes, but results remain inconclusive due to heterogeneous study design and the presence of cofounders. During sleep main confounders such as physical activity and marked temperature changes decrease. Therefore, we measured EDA with wearable devices during the day and night to explore whether EDA is a better biomarker of mood episodes during sleep. We analysed 140 participants from the TIMEBASE study, 102

Objective and quantitative assessment of the level of consciousness is a medical demand in clinics and a theoretical challenge to be addressed. Although a growing body of literature suggests different measures to distinguish the levels of consciousness, a systematic comparison of different measures is lacking. Such a systematic comparison, however, is necessary since it assures us of the best solutions to the problem in terms of prediction accuracy and explanatory power but also simplicity and applicability. In this study, we propose taking a massive comparative approach to assess the level of

…Here we show that during wakefulness, the neuronal assemblies evoked by sounds in the auditory cortex and thalamus are specific to the stimulus and distinct from the assemblies observed in ongoing activity. In contrast, during anesthesia, evoked assemblies are indistinguishable from ongoing assemblies in the cortex, while they remain distinct in the thalamus. A strong remapping of sensory responses accompanies this d

…evidence showing that sleep and wakefulness can actually intermingle and that wake-like and sleep-like activity can be observed concomitantly in different brain regions. I will here explore the implications of this conception of sleep as a local phenomenon for cognition and consciousness. In the first part of my presentation, I will show how local modulations of sleep depth during sleep could support the processing of sensory information by sleepers. I will also how, under certain circumstances, sleepers c

…is mostly revealed during wakefulness, the sleeping brain might offer another view into physiological and pathological brain connectivity. Furthermore, there is a large body of evidence supporting that sleep mediates plastic changes in brain connectivity. Although brain plasticity depends on environmental input which is provided in the waking state, disconnection during sleep might be necessary for integrating new into existing information and at the same time restoring brain effic