Consciousness is reduced during nonrapid eye movement (NREM) sleep due to changes in brain function that are still poorly understood. Here, we tested the hypothesis that impaired consciousness during NREM sleep is associated with an increased modularity of brain activity. Cerebral connectivity was quantified in resting-state functional magnetic resonance imaging times series acquired in 13...
Journal of Sleep ResearchFebruary 1, 2012Caroline Kusse, Anahita Shaffii-LE Bourdiec, Jessica Schrouff et al.
This study characterizes hypnagogic hallucinations reported during a polygraphically recorded 90-min daytime nap following or preceding practice of the computer game Tetris. In the experimental group (N = 16), participants played Tetris in the morning for 2 h during three consecutive days, while in a first control group (N = 13, controlling the effect of experience) participants did not play...
The vegetative state is a devastating condition where patients awaken from their coma (i.e., open their eyes) but fail to show any behavioural sign of conscious awareness. Locked-in syndrome patients also awaken from their coma and are unable to show any motor response to command (except for small eye movements or blinks) but recover full conscious awareness of self and environment. Bedside...
Consciousness has been related to the amount of integrated information that the brain is able to generate. In this paper, we tested the hypothesis that the loss of consciousness caused by propofol anesthesia is associated with a significant reduction in the capacity of the brain to integrate information. To assess the functional structure of the whole brain, functional integration and partial...
The default mode network (DMN) is a set of brain regions that consistently shows higher activity at rest compared to tasks requiring sustained focused attention toward externally presented stimuli. The cognitive processes that the DMN possibly underlies remain a matter of debate. It has alternately been proposed that DMN activity reflects unfocused attention toward external stimuli or the...
Resting state fMRI (functional magnetic resonance imaging) acquisitions are characterized by low-frequency spontaneous activity in a default mode network (encompassing medial brain areas and linked to self-related processes) and an anticorrelated "extrinsic" system (encompassing lateral frontoparietal areas and modulated via external sensory stimulation). In order to better determine the...
BACKGROUND: Mechanisms of anesthesia-induced loss of consciousness remain poorly understood. Resting-state functional magnetic resonance imaging allows investigating whole-brain connectivity changes during pharmacological modulation of the level of consciousness. METHODS: Low-frequency spontaneous blood oxygen level-dependent fluctuations were measured in 19 healthy volunteers during...
The origin of within-subject variability in perceptual experiments is poorly understood. We here review evidence that baseline brain activity in the areas involved in sensory perception predict subsequent variations in sensory awareness. We place these findings in light of recent findings on the architecture of spontaneous BOLD fluctuations in the awake human brain, and discuss the possible...
Spontaneous brain activity has recently received increasing interest in the neuroimaging community. However, the value of resting-state studies to a better understanding of brain-behavior relationships has been challenged. That altered states of consciousness are a privileged way to study the relationships between spontaneous brain activity and behavior is proposed, and common resting-state...
Our neurobiological knowledge about human dream organisation results primarily from the study of Rapid-Eye-Movement (REM) sleep.In humans, functional neuroimaging techniques, using H 2 15 O or 18 FDG positron emission tomography (PET) and functional magnetic resonance imaging (fMRI), allowed the mapping of the regional cerebral activity during this sleep stage, which is dominated by the...
Sleep and dream research has recently been invigorated by convergent data from complementary neuropsychological sources such as brain-imaging studies of normal sleep, clinical investigations of dream disorders in brain-damaged patients and analyses of dream reports from healthy individuals. Here we show that by adopting a neuropsychological approach to dream phenomenology we can gain important...
In this chapter, we aimed at further characterizing the functional neuroanatomy of the human rapid eye movement (REM) sleep at the population level. We carried out a meta-analysis of a large dataset of positron emission tomography (PET) scans acquired during wakefulness, slow wave sleep and REM sleep, and focused especially on the brain areas in which the activity diminishes during REM sleep....