-
Sleep Medicine Jul 2021We reviewed current definitions of vigilance to propose a definition, applicable in sleep medicine. As previous definitions contained terms such as attention, alertness,... (Review)
Review
We reviewed current definitions of vigilance to propose a definition, applicable in sleep medicine. As previous definitions contained terms such as attention, alertness, and arousal, we addressed these concepts too. We defined alertness as a quantitative measure of the mind state governing sensitivity to stimuli. Arousal comprises a stimulus-induced upward change in alertness, irrespective of the subsequent duration of the increased level of alertness. Vigilance is defined as the capability to be sensitive to potential changes in one's environment, ie the capability to reach a level of alertness above a threshold for a certain period of time rather than the state of alertness itself. It has quantitative and temporal dimensions. Attention adds direction towards a stimulus to alertness, requiring cognitive control: it involves being prepared to process stimuli coming from an expected direction. Sustained attention corresponds to a state in which some level of attention is purposefully maintained, adding a time factor to the definition of attention. Vigilance differs from sustained attention in that the latter in addition implies a direction to which attention is cognitively directed as well as a specification of duration. Attempts to measure vigilance, however, are often in fact measurements of sustained attention.
Topics: Arousal; Attention; Humans; Reaction Time; Time Factors; Wakefulness
PubMed: 34022494
DOI: 10.1016/j.sleep.2021.04.038 -
Neuroscience and Biobehavioral Reviews Sep 2016Why do animals and humans do anything at all? Arousal is the most powerful and essential function of the brain, a continuous function that accounts for the ability of... (Review)
Review
Why do animals and humans do anything at all? Arousal is the most powerful and essential function of the brain, a continuous function that accounts for the ability of animals and humans to respond to stimuli in the environment by producing muscular responses. Following decades of psychological, neurophysiological and molecular investigations, generalized CNS arousal can now be analyzed using approaches usually applied to physical systems. The concept of "criticality" is a state that illustrates an advantage for arousal systems poised near a phase transition. This property provides speed and sensitivity and facilitates the transition of the system into different brain states, especially as the brain crosses a phase transition from less aroused to more aroused states. In summary, concepts derived from applied mathematics of physical systems will now find their application in this area of neuroscience, the neurobiology of CNS arousal.
Topics: Animals; Arousal; Brain; Central Nervous System; Humans; Neurobiology; Vertebrates; Wakefulness
PubMed: 27216213
DOI: 10.1016/j.neubiorev.2016.05.014 -
Nature Communications Apr 2023Despite extensive research on astrocytic Ca in synaptic transmission, its contribution to the modulation of sensory transmission during different brain states remains...
Despite extensive research on astrocytic Ca in synaptic transmission, its contribution to the modulation of sensory transmission during different brain states remains largely unknown. Here, by using two-photon microscopy and whole-cell recordings, we show two distinct astrocytic Ca signals in the murine barrel cortex: a small, long-lasting Ca increase during sleep and a large, widespread but short-lasting Ca spike when aroused. The large Ca wave in aroused mice was inositol trisphosphate (IP3)-dependent, evoked by the locus coeruleus-norepinephrine system, and enhanced sensory input, contributing to reliable sensory transmission. However, the small Ca transient was IP3-independent and contributed to decreased extracellular K, hyperpolarization of the neurons, and suppression of sensory transmission. These events respond to different pharmacological inputs and contribute to distinct sleep and arousal functions by modulating the efficacy of sensory transmission. Together, our data demonstrate an important function for astrocytes in sleep and arousal states via astrocytic Ca waves.
Topics: Mice; Animals; Wakefulness; Astrocytes; Calcium Signaling; Arousal; Sleep
PubMed: 37069258
DOI: 10.1038/s41467-023-37974-z -
Experimental Physiology Jan 1996This review has described the many behavioural and arousal-related influences on breathing and the extent of these influences in humans. The chief examples have included... (Review)
Review
This review has described the many behavioural and arousal-related influences on breathing and the extent of these influences in humans. The chief examples have included the effect on breathing of altered mental activity, wakefulness and sleep, and learned respiratory responses. Determining the precise neurological mechanisms underlying these effects represents a difficult challenge to respiratory physiologists who seek to understand the respiratory control system of awake behaving humans. Nevertheless, insight into the various forebrain and brainstem inputs to respiratory muscles has been gained by studies of breathing during particular behaviours (when either voluntary or reflex breathing predominates) or in particular neurological patients (in whom either voluntary or reflex breathing is defective). With developments in brain imaging techniques, such as functional magnetic resonance imaging, it may soon be possible to determine more precisely the various anatomical sources and timing of the motor commands to breathe during different behaviours, states of arousal and sleep.
Topics: Arousal; Behavior; Drive; Humans; Nervous System Physiological Phenomena; Respiration; Sleep; Wakefulness
PubMed: 8869137
DOI: 10.1113/expphysiol.1996.sp003911 -
Sensors (Basel, Switzerland) Nov 2021Drowsiness is among the important factors that cause traffic accidents; therefore, a monitoring system is necessary to detect the state of a driver's drowsiness. Driver... (Review)
Review
Drowsiness is among the important factors that cause traffic accidents; therefore, a monitoring system is necessary to detect the state of a driver's drowsiness. Driver monitoring systems usually detect three types of information: biometric information, vehicle behavior, and driver's graphic information. This review summarizes the research and development trends of drowsiness detection systems based on various methods. Drowsiness detection methods based on the three types of information are discussed. A prospect for arousal level detection and estimation technology for autonomous driving is also presented. In the case of autonomous driving levels 4 and 5, where the driver is not the primary driving agent, the technology will not be used to detect and estimate wakefulness for accident prevention; rather, it can be used to ensure that the driver has enough sleep to arrive comfortably at the destination.
Topics: Accidents, Traffic; Automobile Driving; Sleep; Technology; Wakefulness
PubMed: 34883924
DOI: 10.3390/s21237921 -
Cells Nov 2023The study of functions, mechanisms of generation, and pathways of movement of cerebral fluids has a long history, but the last decade has been especially productive. The... (Review)
Review
The study of functions, mechanisms of generation, and pathways of movement of cerebral fluids has a long history, but the last decade has been especially productive. The proposed glymphatic hypothesis, which suggests a mechanism of the brain waste removal system (BWRS), caused an active discussion on both the criticism of some of the perspectives and our intensive study of new experimental facts. It was especially found that the intensity of the metabolite clearance changes significantly during the transition between sleep and wakefulness. Interestingly, at the cellular level, a number of aspects of this problem have been focused on, such as astrocytes-glial cells, which, over the past two decades, have been recognized as equal partners of neurons and perform many important functions. In particular, an important role was assigned to astrocytes within the framework of the glymphatic hypothesis. In this review, we return to the "astrocytocentric" view of the BWRS function and the explanation of its activation during sleep from the viewpoint of new findings over the last decade. Our main conclusion is that the BWRS's action may be analyzed both at the systemic (whole-brain) and at the local (cellular) level. The local level means here that the neuro-glial-vascular unit can also be regarded as the smallest functional unit of sleep, and therefore, the smallest functional unit of the BWRS.
Topics: Astrocytes; Brain; Sleep; Neuroglia; Wakefulness
PubMed: 37998402
DOI: 10.3390/cells12222667 -
Journal of Neuroscience Methods Oct 2023Characterization of normal arousal states has been achieved by fitting predictions of corticothalamic neural field theory (NFT) to electroencephalographic (EEG) spectra...
BACKGROUND
Characterization of normal arousal states has been achieved by fitting predictions of corticothalamic neural field theory (NFT) to electroencephalographic (EEG) spectra to yield relevant physiological parameters.
NEW METHOD
A prior fitting method is extended to distinguish conscious and unconscious states in healthy and brain injured subjects by identifying additional parameters and clusters in parameter space.
RESULTS
Fits of NFT predictions to EEG spectra are used to estimate neurophysiological parameters in healthy and brain injured subjects. Spectra are used from healthy subjects in wake and sleep and from patients with unresponsive wakefulness syndrome, in a minimally conscious state (MCS), and emerged from MCS. Subjects cluster into three groups in parameter space: conscious healthy (wake and REM), sleep, and brain injured. These are distinguished by the difference X-Y between corticocortical (X) and corticothalamic (Y) feedbacks, and by mean neural response rates α and β to incoming spikes. X-Y tracks consciousness in healthy individuals, with smaller values in wake/REM than sleep, but cannot distinguish between brain injuries. Parameters α and β differentiate deep sleep from wake/REM and brain injury.
COMPARISON WITH EXISTING METHODS
Other methods typically rely on laborious clinical assessment, manual EEG scoring, or evaluation of measures like Φ from integrated information theory, for which no efficient method exists. In contrast, the present method can be automated on a personal computer.
CONCLUSION
The method provides a means to quantify consciousness and arousal in healthy and brain injured subjects, but does not distinguish subtypes of brain injury.
Topics: Humans; Consciousness; Arousal; Brain; Wakefulness; Electroencephalography; Brain Injuries
PubMed: 37661056
DOI: 10.1016/j.jneumeth.2023.109958 -
Revista Brasileira de Psiquiatria (Sao... May 2005Neurochemically distinct systems interact regulating sleep and wakefulness. Wakefulness is promoted by aminergic, acetylcholinergic brainstem and hypothalamic systems.... (Review)
Review
Neurochemically distinct systems interact regulating sleep and wakefulness. Wakefulness is promoted by aminergic, acetylcholinergic brainstem and hypothalamic systems. Each of these arousal systems supports wakefulness and coordinated activity is required for alertness and EEG activation. Neurons in the pons and preoptic area control rapid eye movement and non-rapid eye movement sleep. Mutual inhibition between these wake- and sleep-regulating systems generate behavioral states. An up-to-date understanding of these systems should allow clinicians and researchers to better understand the effects of drugs, lesions, and neurologic disease on sleep and wakefulness.
Topics: Activity Cycles; Electromyography; Electrophysiology; Humans; Hypothalamus; Neurons; Neurotransmitter Agents; Sleep Stages; Wakefulness
PubMed: 16082453
DOI: 10.1590/s1516-44462005000500007 -
PLoS Computational Biology Oct 2022Paying attention to particular aspects of the world or being more vigilant in general can be interpreted as forms of 'internal' action. Such arousal-related choices come...
Paying attention to particular aspects of the world or being more vigilant in general can be interpreted as forms of 'internal' action. Such arousal-related choices come with the benefit of increasing the quality and situational appropriateness of information acquisition and processing, but incur potentially expensive energetic and opportunity costs. One implementational route for these choices is widespread ascending neuromodulation, including by acetylcholine (ACh). The key computational question that elective attention poses for sensory processing is when it is worthwhile paying these costs, and this includes consideration of whether sufficient information has yet been collected to justify the higher signal-to-noise ratio afforded by greater attention and, particularly if a change in attentional state is more expensive than its maintenance, when states of heightened attention ought to persist. We offer a partially observable Markov decision-process treatment of optional attention in a detection task, and use it to provide a qualitative model of the results of studies using modern techniques to measure and manipulate ACh in rodents performing a similar task.
Topics: Acetylcholine; Arousal; Wakefulness
PubMed: 36315594
DOI: 10.1371/journal.pcbi.1010642 -
Sleep Medicine Reviews Feb 2011The histaminergic system is exclusively localized within the posterior hypothalamus with projection to almost all the major regions of the central nervous system. Strong... (Review)
Review
The histaminergic system is exclusively localized within the posterior hypothalamus with projection to almost all the major regions of the central nervous system. Strong and consistent evidence exist to suggest that histamine, acting via H₁ and/or H₃ receptor has a pivotal role in the regulation of sleep-wakefulness. Administration of histamine or H₁ receptor agonists induces wakefulness, whereas administration of H₁ receptor antagonists promotes sleep. The H₃ receptor functions as an auto-receptor and regulates the synthesis and release of histamine. Activation of H₃ receptor reduces histamine release and promotes sleep. Conversely, blockade of H₃ receptor promotes wakefulness. Histamine release in the hypothalamus and other target regions is highest during wakefulness. The histaminergic neurons display maximal activity during the state of high vigilance, and cease their activity during non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. The cerebrospinal levels of histamine are reduced in diseased states where hypersomnolence is a major symptom. The histamine deficient L-histidine decarboxylase knockout (HDC KO) mice display sleep fragmentation and increased REM sleep during the light period along with profound wakefulness deficit at dark onset, and in novel environment. Similar results have been obtained when histamine neurons are lesioned. These studies strongly implicate the histaminergic neurons of the TMN to play a critical role in the maintenance of high vigilance state during wakefulness.
Topics: Animals; Arousal; Histamine; Humans; Mice; Mice, Knockout; Receptors, Cell Surface; Receptors, Histamine H1; Receptors, Neuropeptide; Sleep; Sleep Disorders, Intrinsic; Sleep, REM; Wakefulness
PubMed: 20851648
DOI: 10.1016/j.smrv.2010.06.004