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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 -
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 -
Neuron May 2013Brain rhythms regulate information processing in different states to enable learning and memory formation. The <1 Hz sleep slow oscillation hallmarks slow-wave sleep and...
Brain rhythms regulate information processing in different states to enable learning and memory formation. The <1 Hz sleep slow oscillation hallmarks slow-wave sleep and is critical to memory consolidation. Here we show in sleeping humans that auditory stimulation in phase with the ongoing rhythmic occurrence of slow oscillation up states profoundly enhances the slow oscillation rhythm, phase-coupled spindle activity, and, consequently, the consolidation of declarative memory. Stimulation out of phase with the ongoing slow oscillation rhythm remained ineffective. Closed-loop in-phase stimulation provides a straight-forward tool to enhance sleep rhythms and their functional efficacy.
Topics: Acoustic Stimulation; Adult; Brain; Brain Waves; Electroencephalography; Female; Humans; Male; Memory; Neurons; Neuropsychological Tests; Periodicity; Polysomnography; Sleep
PubMed: 23583623
DOI: 10.1016/j.neuron.2013.03.006 -
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 -
Nature Reviews. Neuroscience Apr 2016The hippocampal local field potential (LFP) shows three major types of rhythms: theta, sharp wave-ripples and gamma. These rhythms are defined by their frequencies, they... (Review)
Review
The hippocampal local field potential (LFP) shows three major types of rhythms: theta, sharp wave-ripples and gamma. These rhythms are defined by their frequencies, they have behavioural correlates in several species including rats and humans, and they have been proposed to carry out distinct functions in hippocampal memory processing. However, recent findings have challenged traditional views on these behavioural functions. In this Review, I discuss our current understanding of the origins and the mnemonic functions of hippocampal theta, sharp wave-ripples and gamma rhythms on the basis of findings from rodent studies. In addition, I present an updated synthesis of their roles and interactions within the hippocampal network.
Topics: Animals; Brain Waves; Hippocampus; Humans; Learning; Nerve Net; Periodicity
PubMed: 26961163
DOI: 10.1038/nrn.2016.21 -
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 -
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