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Science (New York, N.Y.) Oct 2021Sleep is crucial for healthy cognition, including memory. The two main phases of sleep, REM (rapid eye movement) and non-REM sleep, are associated with characteristic... (Review)
Review
Sleep is crucial for healthy cognition, including memory. The two main phases of sleep, REM (rapid eye movement) and non-REM sleep, are associated with characteristic electrophysiological patterns that are recorded using surface and intracranial electrodes. These patterns include sharp-wave ripples, cortical slow oscillations, delta waves, and spindles during non-REM sleep and theta oscillations during REM sleep. They reflect the precisely timed activity of underlying neural circuits. Here, we review how these electrical signatures have been guiding our understanding of the circuits and processes sustaining memory consolidation during sleep, focusing on hippocampal theta oscillations and sharp-wave ripples and how they coordinate with cortical patterns. Finally, we highlight how these brain patterns could also sustain sleep-dependent homeostatic processes and evoke several potential future directions for research on the memory function of sleep.
Topics: Animals; Brain Waves; Cerebral Cortex; Hippocampus; Homeostasis; Humans; Memory Consolidation; Neural Pathways; Sleep Stages; Sleep, REM; Theta Rhythm
PubMed: 34709916
DOI: 10.1126/science.abi8370 -
Science (New York, N.Y.) Oct 2021Sleep is essential for brain function in a surprisingly diverse set of ways. In the short term, lack of sleep leads to impaired memory and attention; in the longer term,... (Review)
Review
Sleep is essential for brain function in a surprisingly diverse set of ways. In the short term, lack of sleep leads to impaired memory and attention; in the longer term, it produces neurological dysfunction or even death. I discuss recent advances in understanding how sleep maintains the physiological health of the brain through interconnected systems of neuronal activity and fluid flow. The neural dynamics that appear during sleep are intrinsically coupled to its consequences for blood flow, cerebrospinal fluid dynamics, and waste clearance. Recognizing these linked causes and consequences of sleep has shed new light on why sleep is important for such disparate aspects of brain function.
Topics: Animals; Brain; Brain Waves; Cerebrospinal Fluid; Cerebrovascular Circulation; Humans; Neural Pathways; Neurons; Sleep; Sleep Stages
PubMed: 34709917
DOI: 10.1126/science.abi8375 -
Science (New York, N.Y.) Nov 2019Sleep is essential for both cognition and maintenance of healthy brain function. Slow waves in neural activity contribute to memory consolidation, whereas cerebrospinal...
Sleep is essential for both cognition and maintenance of healthy brain function. Slow waves in neural activity contribute to memory consolidation, whereas cerebrospinal fluid (CSF) clears metabolic waste products from the brain. Whether these two processes are related is not known. We used accelerated neuroimaging to measure physiological and neural dynamics in the human brain. We discovered a coherent pattern of oscillating electrophysiological, hemodynamic, and CSF dynamics that appears during non-rapid eye movement sleep. Neural slow waves are followed by hemodynamic oscillations, which in turn are coupled to CSF flow. These results demonstrate that the sleeping brain exhibits waves of CSF flow on a macroscopic scale, and these CSF dynamics are interlinked with neural and hemodynamic rhythms.
Topics: Adult; Brain; Brain Waves; Cerebrospinal Fluid; Cerebrovascular Circulation; Delta Rhythm; Electroencephalography; Female; Hemodynamics; Humans; Magnetic Resonance Imaging; Male; Sleep; Young Adult
PubMed: 31672896
DOI: 10.1126/science.aax5440 -
Annual Review of Neuroscience 2012Gamma rhythms are commonly observed in many brain regions during both waking and sleep states, yet their functions and mechanisms remain a matter of debate. Here we... (Review)
Review
Gamma rhythms are commonly observed in many brain regions during both waking and sleep states, yet their functions and mechanisms remain a matter of debate. Here we review the cellular and synaptic mechanisms underlying gamma oscillations and outline empirical questions and controversial conceptual issues. Our main points are as follows: First, gamma-band rhythmogenesis is inextricably tied to perisomatic inhibition. Second, gamma oscillations are short-lived and typically emerge from the coordinated interaction of excitation and inhibition, which can be detected as local field potentials. Third, gamma rhythm typically concurs with irregular firing of single neurons, and the network frequency of gamma oscillations varies extensively depending on the underlying mechanism. To document gamma oscillations, efforts should be made to distinguish them from mere increases of gamma-band power and/or increased spiking activity. Fourth, the magnitude of gamma oscillation is modulated by slower rhythms. Such cross-frequency coupling may serve to couple active patches of cortical circuits. Because of their ubiquitous nature and strong correlation with the "operational modes" of local circuits, gamma oscillations continue to provide important clues about neuronal population dynamics in health and disease.
Topics: Action Potentials; Animals; Brain; Brain Waves; Humans; Membrane Potentials; Models, Neurological; Neural Inhibition; Neural Pathways
PubMed: 22443509
DOI: 10.1146/annurev-neuro-062111-150444 -
Hippocampus Oct 2015Sharp wave ripples (SPW-Rs) represent the most synchronous population pattern in the mammalian brain. Their excitatory output affects a wide area of the cortex and... (Review)
Review
Sharp wave ripples (SPW-Rs) represent the most synchronous population pattern in the mammalian brain. Their excitatory output affects a wide area of the cortex and several subcortical nuclei. SPW-Rs occur during "off-line" states of the brain, associated with consummatory behaviors and non-REM sleep, and are influenced by numerous neurotransmitters and neuromodulators. They arise from the excitatory recurrent system of the CA3 region and the SPW-induced excitation brings about a fast network oscillation (ripple) in CA1. The spike content of SPW-Rs is temporally and spatially coordinated by a consortium of interneurons to replay fragments of waking neuronal sequences in a compressed format. SPW-Rs assist in transferring this compressed hippocampal representation to distributed circuits to support memory consolidation; selective disruption of SPW-Rs interferes with memory. Recently acquired and pre-existing information are combined during SPW-R replay to influence decisions, plan actions and, potentially, allow for creative thoughts. In addition to the widely studied contribution to memory, SPW-Rs may also affect endocrine function via activation of hypothalamic circuits. Alteration of the physiological mechanisms supporting SPW-Rs leads to their pathological conversion, "p-ripples," which are a marker of epileptogenic tissue and can be observed in rodent models of schizophrenia and Alzheimer's Disease. Mechanisms for SPW-R genesis and function are discussed in this review.
Topics: Animals; Biomarkers; Brain Waves; Executive Function; Hippocampus; Humans; Memory, Episodic
PubMed: 26135716
DOI: 10.1002/hipo.22488 -
Molecules (Basel, Switzerland) Oct 2020Tangerine () is one of the most important crops of Thailand with a total harvest that exceeds 100,000 tons. Citrus essential oils are widely used as aromatherapy and...
Tangerine () is one of the most important crops of Thailand with a total harvest that exceeds 100,000 tons. Citrus essential oils are widely used as aromatherapy and medicinal agents. The effect of tangerine essential oil on human brain waves and sleep activity has not been reported. In the present study, we therefore evaluated these effects of tangerine essential oil by measurement of electroencephalography (EEG) activity with 32 channel platforms according to the international 10-20 system in 10 male and 10 female subjects. Then the sleep onset latency was studied to further confirm the effect on sleep activity. The results revealed that different concentrations, subthreshold to suprathreshold, of tangerine oil gave different brain responses. Undiluted tangerine oil inhalation reduced slow and fast alpha wave powers and elevated low and mid beta wave powers. The subthreshold and threshold dilution showed the opposite effect to the brain compared with suprathreshold concentration. Inhalation of threshold concentration showed effectively decreased alpha and beta wave powers and increased theta wave power, which emphasize its sedative effect. The reduction of sleep onset latency was confirmed with the implementation of the observed sedative effect of tangerine oil.
Topics: Adult; Brain Waves; Citrus; Electroencephalography; Female; Humans; Male; Oils, Volatile; Sleep Latency; Young Adult
PubMed: 33096890
DOI: 10.3390/molecules25204865 -
Current Biology : CB Oct 2018Schönauer and Pöhlchen introduce the reader to sleep spindles, brain oscillations that occur during nREM sleep that are thought to function in the stabilization of... (Review)
Review
Schönauer and Pöhlchen introduce the reader to sleep spindles, brain oscillations that occur during nREM sleep that are thought to function in the stabilization of memories.
Topics: Brain; Brain Waves; Cognition; Electroencephalography; Humans; Memory; Sleep; Sleep Stages
PubMed: 30300592
DOI: 10.1016/j.cub.2018.07.035 -
Trends in Cognitive Sciences Oct 2018Behavioral and brain rhythms in the millisecond-to-second range are central in human music, speech, and movement. A comparative approach can further our understanding of... (Review)
Review
Behavioral and brain rhythms in the millisecond-to-second range are central in human music, speech, and movement. A comparative approach can further our understanding of the evolution of rhythm processing by identifying behavioral and neural similarities and differences across cognitive domains and across animal species. We provide an overview of research into rhythm cognition in music, speech, and animal communication. Rhythm has received considerable attention within each individual field, but to date, little integration. This review article on rhythm processing incorporates and extends existing ideas on temporal processing in speech and music and offers suggestions about the neural, biological, and evolutionary bases of human abilities in these domains.
Topics: Animal Communication; Animals; Auditory Perception; Biological Evolution; Brain Waves; Humans; Music; Speech Perception; Time Perception
PubMed: 30266149
DOI: 10.1016/j.tics.2018.08.002 -
British Journal of Clinical Pharmacology Jan 2014To assess centrally mediated analgesic mechanisms in clinical trials with pain patients, objective standardized methods such as electroencephalography (EEG) has many... (Review)
Review
To assess centrally mediated analgesic mechanisms in clinical trials with pain patients, objective standardized methods such as electroencephalography (EEG) has many advantages. The aim of this review is to provide the reader with an overview of present findings in analgesics assessed with spontaneous EEG and evoked brain potentials (EPs) in humans. Furthermore, EEG methodologies will be discussed with respect to translation from animals to humans and future perspectives in predicting analgesic efficacy. We searched PubMed with MeSH terms 'analgesics', 'electroencephalography' and 'evoked potentials' for relevant articles. Combined with a search in their reference lists 15 articles on spontaneous EEG and 55 papers on EPs were identified. Overall, opioids produced increased activity in the delta band in the spontaneous EEG, but increases in higher frequency bands were also seen. The EP amplitudes decreased in the majority of studies. Anticonvulsants used as analgesics showed inconsistent results. The N-methyl-D-aspartate receptor antagonist ketamine showed an increase in the theta band in spontaneous EEG and decreases in EP amplitudes. Tricyclic antidepressants increased the activity in the delta, theta and beta bands in the spontaneous EEG while EPs were inconsistently affected. Weak analgesics were mainly investigated with EPs and a decrease in amplitudes was generally observed. This review reveals that both spontaneous EEG and EPs are widely used as biomarkers for analgesic drug effects. Methodological differences are common and a more uniform approach will further enhance the value of such biomarkers for drug development and prediction of treatment response in individual patients.
Topics: Analgesics; Animals; Brain Waves; Electroencephalography; Evoked Potentials; Humans
PubMed: 23593934
DOI: 10.1111/bcp.12137 -
Neuron Oct 2019Magnetoencephalography (MEG) is an invaluable tool to study the dynamics and connectivity of large-scale brain activity and their interactions with the body and the... (Review)
Review
Magnetoencephalography (MEG) is an invaluable tool to study the dynamics and connectivity of large-scale brain activity and their interactions with the body and the environment in functional and dysfunctional body and brain states. This primer introduces the basic concepts of MEG, discusses its strengths and limitations in comparison to other brain imaging techniques, showcases interesting applications, and projects exciting current trends into the near future, in a way that might more fully exploit the unique capabilities of MEG.
Topics: Brain; Brain Mapping; Brain Waves; Cognitive Neuroscience; Functional Neuroimaging; Humans; Magnetoencephalography; Neural Pathways; Neuroimaging
PubMed: 31647893
DOI: 10.1016/j.neuron.2019.07.001