Theta bursts precede, and spindles follow, cortical and thalamic downstates in human NREM sleep

Abstract:Since their discovery, slow oscillations have been observed to group spindles during non-REM sleep. Previous studies assert that the slow oscillation downstate (DS) is preceded by slow spindles (10-12Hz), and followed by fast spindles (12-16Hz). Here, using both direct transcortical recordings in patients with intractable epilepsy (n=10, 8 female), as well as scalp EEG recordings from a healthy cohort (n=3, 1 female), we find in multiple cortical areas that both slow and fast spindles follow the DS. Although discrete oscillations do precede DSs, they are theta bursts (TB) centered at 5-8Hz. TBs were more pronounced for DSs in NREM stage N2 compared with N3. TB with similar properties occur in the thalamus, but unlike spindles they have no clear temporal relationship with cortical TB. These differences in corticothalamic dynamics, as well as differences between spindles and theta in coupling high frequency content, are consistent with NREM theta having separate generative mechanisms from spindles. The final inhibitory cycle of the TB coincides with the DS peak, suggesting that in N2, TB may help trigger the DS. Since the transition to N1 is marked by the appearance of theta, and the transition to N2 by the appearance of DS and thus spindles, a role of TB in triggering DS could help explain the sequence of electrophysiological events characterizing sleep. Finally, the coordinated appearance of spindles and DSs are implicated in memory consolidation processes, and the current findings redefine their temporal coupling with theta during NREM sleep.Significance StatementSleep is characterized by large slow waves which modulate brain activity. Prominent among these are ‘downstates,’ periods of a few tenths of a second when most cells stop firing, and ‘spindles,’ oscillations at about twelve times a second lasting for about a second. In this study, we provide the first detailed description of another kind of sleep wave: ‘theta bursts,’ a brief oscillation at about six cycles per second. We show, recording during natural sleep directly from the human cortex and thalamus, as well as on the human scalp, that theta bursts precede, and spindles follow downstates. Theta bursts may help trigger downstates in some circumstances, and organize cortical and thalamic activity so that memories can be consolidated during sleep.

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Endogenous memory reactivation during sleep in humans is clocked by slow oscillation-spindle complexes

Nature Communications ◽

10.1038/s41467-021-23520-2 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Thomas Schreiner ◽

Marit Petzka ◽

Tobias Staudigl ◽

Bernhard P. Staresina

Keyword(s):

Memory Function ◽

Nrem Sleep ◽

Stimulus Category ◽

Learning Material ◽

Memory Reactivation ◽

Eeg Recordings ◽

Surface Eeg ◽

Function Of Sleep ◽

Prior Experiences

AbstractSleep is thought to support memory consolidation via reactivation of prior experiences, with particular electrophysiological sleep signatures (slow oscillations (SOs) and sleep spindles) gating the information flow between relevant brain areas. However, empirical evidence for a role of endogenous memory reactivation (i.e., without experimentally delivered memory cues) for consolidation in humans is lacking. Here, we devised a paradigm in which participants acquired associative memories before taking a nap. Multivariate decoding was then used to capture endogenous memory reactivation during non-rapid eye movement (NREM) sleep in surface EEG recordings. Our results reveal reactivation of learning material during SO-spindle complexes, with the precision of SO-spindle coupling predicting reactivation strength. Critically, reactivation strength (i.e. classifier evidence in favor of the previously studied stimulus category) in turn predicts the level of consolidation across participants. These results elucidate the memory function of sleep in humans and emphasize the importance of SOs and spindles in clocking endogenous consolidation processes.

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P.129 Bi-insular Responsive Neurostimulation Artifact on Scalp Electroencephalogram

Canadian Journal of Neurological Sciences / Journal Canadien des Sciences Neurologiques ◽

10.1017/cjn.2021.405 ◽

2021 ◽

Vol 48 (s3) ◽

pp. S56-S56

Author(s):

EM Paredes-Aragón ◽

M Chávez-Castillo ◽

GL Barkley ◽

JG Burneo ◽

A Suller-Martí

Keyword(s):

Scientific Literature ◽

Seizure Activity ◽

Epileptiform Activity ◽

Scalp Eeg ◽

Proven Efficacy ◽

Eeg Recordings ◽

Scalp Electroencephalogram ◽

Intracranial Electroencephalography

Background: Background: Responsive Neurostimulation (RNS) has proven efficacy in treating medically resistant epilepsy as an intracranial system detecting, recording and treating seizures automatically. No information exists pertaining to artifact characteristics of RNS findings in scalp EEG. Methods: A 30 year-old female was diagnosed using intracranial electroencephalography(iEEG), with bi-insular epilepsy, of unknown cause. She presented large number of focal unaware non-motor seizures and seizures with progression to bilateral tonic-clonic. She was implanted with bi-insular RNS. Results: During scalp EEG recordings, a prominent artifact was seen corresponding to an automatized discharge suspectedly evoked by the RNS trying to minimize the frequent epileptiform activity in her case. Figure 1 and 2 depict these findings. Conclusions: Artifact seen by the RNS in scalp EEG has not been previously described in scientific literature. These findings must be identified to better characterize the role of the RNS in EEG and treatment of seizure activity visible on scalp recordings.

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Sleep is more than rest for plasticity in the human cortex

SLEEP ◽

10.1093/sleep/zsaa216 ◽

2021 ◽

Author(s):

Christoph Nissen ◽

Hannah Piosczyk ◽

Johannes Holz ◽

Jonathan G Maier ◽

Lukas Frase ◽

...

Keyword(s):

Visual Cortex ◽

Primary Visual Cortex ◽

Neural Plasticity ◽

Discrimination Task ◽

Cortical Plasticity ◽

Brain Activity ◽

Nrem Sleep ◽

Human Cortex ◽

Healthy Humans ◽

Active Wakefulness

Abstract Sleep promotes adaptation of behavior and underlying neural plasticity in comparison to active wakefulness. However, the contribution of its two main characteristics, sleep-specific brain activity and reduced stimulus interference, remains unclear. We tested healthy humans on a texture discrimination task, a proxy for neural plasticity in primary visual cortex, in the morning and retested them in the afternoon after a period of daytime sleep, passive waking with maximally reduced interference, or active waking. Sleep restored performance in direct comparison to both passive and active waking, in which deterioration of performance across repeated within-day testing has been linked to synaptic saturation in the primary visual cortex. No difference between passive and active waking was observed. Control experiments indicated that deterioration across wakefulness was retinotopically specific to the trained visual field and not due to unspecific performance differences. The restorative effect of sleep correlated with time spent in NREM sleep and with electroencephalographic slow wave energy, which is thought to reflect renormalization of synaptic strength. The results indicate that sleep is more than a state of reduced stimulus interference, but that sleep-specific brain activity restores performance by actively refining cortical plasticity.

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Material and physical model for evaluation of deep brain activity contribution to EEG recordings

Functional Materials Letters ◽

10.1142/s1793604715400032 ◽

2015 ◽

Vol 08 (03) ◽

pp. 1540003 ◽

Cited By ~ 1

Author(s):

Yan Ye ◽

Xiaoping Li ◽

Tiecheng Wu ◽

Zhe Li ◽

Wenwen Xie

Keyword(s):

Neuronal Activity ◽

Surface Potential ◽

Brain Activity ◽

Human Head ◽

Brain Structures ◽

Dipole Source ◽

Head Model ◽

Scalp Eeg ◽

Eeg Recordings ◽

Deep Brain

Deep brain activity is conventionally recorded with surgical implantation of electrodes. During the neurosurgery, brain tissue damage and the consequent side effects to patients are inevitably incurred. In order to eliminate undesired risks, we propose that deep brain activity should be measured using the noninvasive scalp electroencephalography (EEG) technique. However, the deeper the neuronal activity is located, the noisier the corresponding scalp EEG signals are. Thus, the present study aims to evaluate whether deep brain activity could be observed from EEG recordings. In the experiment, a three-layer cylindrical head model was constructed to mimic a human head. A single dipole source (sine wave, 10 Hz, altering amplitudes) was embedded inside the model to simulate neuronal activity. When the dipole source was activated, surface potential was measured via electrodes attached on the top surface of the model and raw data were recorded for signal analysis. Results show that the dipole source activity positioned at 66 mm depth in the model, equivalent to the depth of deep brain structures, is clearly observed from surface potential recordings. Therefore, it is highly possible that deep brain activity could be observed from EEG recordings and deep brain activity could be measured using the noninvasive scalp EEG technique.

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Modality and folk psychology

Studies in history and philosophy of science and technology ◽

10.15421/271903 ◽

2019 ◽

Vol 28 (1) ◽

pp. 19-27

Author(s):

Ja. O. Petik

Keyword(s):

Modal Logic ◽

Brain Activity ◽

Formal System ◽

Philosophy Of Logic ◽

Psychological States ◽

Formal Systems ◽

Modern Psychology ◽

Philosophical Interpretation ◽

Important Direction

The connection of the modern psychology and formal systems remains an important direction of research. This paper is centered on philosophical problems surrounding relations between mental and logic. Main attention is given to philosophy of logic but certain ideas are introduced that can be incorporated into the practical philosophical logic. The definition and properties of basic modal logic and descending ones which are used in study of mental activity are in view. The defining role of philosophical interpretation of modality for the particular formal system used for research in the field of psychological states of agents is postulated. Different semantics of modal logic are studied. The hypothesis about the connection of research in cognitive psychology (semantics of brain activity) and formal systems connected to research of psychological states is stated.

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Delta band activity contributes to the identification of command following in disorder of consciousness

Scientific Reports ◽

10.1038/s41598-021-95818-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Gonzalo Rivera-Lillo ◽

Emmanuel A. Stamatakis ◽

Tristan A. Bekinschtein ◽

David K. Menon ◽

Srivas Chennu

Keyword(s):

Functional Neuroimaging ◽

Brain Activity ◽

Disorder Of Consciousness ◽

Fine Grained ◽

Electrical Brain Activity ◽

Delta Band ◽

Delta Modulation ◽

Command Following ◽

Band Activity

AbstractThe overt or covert ability to follow commands in patients with disorders of consciousness is considered a sign of awareness and has recently been defined as cortically mediated behaviour. Despite its clinical relevance, the brain signatures of the perceptual processing supporting command following have been elusive. This multimodal study investigates the temporal spectral pattern of electrical brain activity to identify features that differentiated healthy controls from patients both able and unable to follow commands. We combined evidence from behavioural assessment, functional neuroimaging during mental imagery and high-density electroencephalography collected during auditory prediction, from 21 patients and 10 controls. We used a penalised regression model to identify command following using features from electroencephalography. We identified seven well-defined spatiotemporal signatures in the delta, theta and alpha bands that together contribute to identify DoC subjects with and without the ability to follow command, and further distinguished these groups of patients from controls. A fine-grained analysis of these seven signatures enabled us to determine that increased delta modulation at the frontal sensors was the main feature in command following patients. In contrast, higher frequency theta and alpha modulations differentiated controls from both groups of patients. Our findings highlight a key role of spatiotemporally specific delta modulation in supporting cortically mediated behaviour including the ability to follow command. However, patients able to follow commands nevertheless have marked differences in brain activity in comparison with healthy volunteers.

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Conditional Entropy: A Potential Digital Marker for Stress

Entropy ◽

10.3390/e23030286 ◽

2021 ◽

Vol 23 (3) ◽

pp. 286

Author(s):

Soheil Keshmiri

Keyword(s):

Resting State ◽

Nearest Neighbor ◽

Brain Activity ◽

Solution Concept ◽

Conditional Entropy ◽

K Nearest Neighbor ◽

Brain Response ◽

Substantial Progress ◽

Eeg Recordings ◽

The Brain

Recent decades have witnessed a substantial progress in the utilization of brain activity for the identification of stress digital markers. In particular, the success of entropic measures for this purpose is very appealing, considering (1) their suitability for capturing both linear and non-linear characteristics of brain activity recordings and (2) their direct association with the brain signal variability. These findings rely on external stimuli to induce the brain stress response. On the other hand, research suggests that the use of different types of experimentally induced psychological and physical stressors could potentially yield differential impacts on the brain response to stress and therefore should be dissociated from more general patterns. The present study takes a step toward addressing this issue by introducing conditional entropy (CE) as a potential electroencephalography (EEG)-based resting-state digital marker of stress. For this purpose, we use the resting-state multi-channel EEG recordings of 20 individuals whose responses to stress-related questionnaires show significantly higher and lower level of stress. Through the application of representational similarity analysis (RSA) and K-nearest-neighbor (KNN) classification, we verify the potential that the use of CE can offer to the solution concept of finding an effective digital marker for stress.

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The relationship between fasting-induced torpor, sleep and waking in laboratory mice

SLEEP ◽

10.1093/sleep/zsab093 ◽

2021 ◽

Author(s):

Yi-Ge Huang ◽

Sarah J Flaherty ◽

Carina A Pothecary ◽

Russell G Foster ◽

Stuart N Peirson ◽

...

Keyword(s):

Body Temperature ◽

Rem Sleep ◽

Brain Activity ◽

Mammalian Species ◽

Nrem Sleep ◽

Laboratory Mice ◽

State Classification ◽

Metabolic Suppression ◽

The Relationship ◽

Electroencephalogram Eeg

Abstract Study objectives Torpor is a regulated and reversible state of metabolic suppression used by many mammalian species to conserve energy. Whereas the relationship between torpor and sleep has been well-studied in seasonal hibernators, less is known about the effects of fasting-induced torpor on states of vigilance and brain activity in laboratory mice. Methods Continuous monitoring of electroencephalogram (EEG), electromyogram (EMG) and surface body temperature was undertaken in adult, male C57BL/6 mice over consecutive days of scheduled restricted feeding. Results All animals showed bouts of hypothermia that became progressively deeper and longer as fasting progressed. EEG and EMG were markedly affected by hypothermia, although the typical electrophysiological signatures of NREM sleep, REM sleep and wakefulness enabled us to perform vigilance-state classification in all cases. Consistent with previous studies, hypothermic bouts were initiated from a state indistinguishable from NREM sleep, with EEG power decreasing gradually in parallel with decreasing surface body temperature. During deep hypothermia, REM sleep was largely abolished, and we observed shivering-associated intense bursts of muscle activity. Conclusions Our study highlights important similarities between EEG signatures of fasting-induced torpor in mice, daily torpor in Djungarian hamsters and hibernation in seasonally-hibernating species. Future studies are necessary to clarify the effects on fasting-induced torpor on subsequent sleep.

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Neural silences can be localized rapidly using noninvasive scalp EEG

Communications Biology ◽

10.1038/s42003-021-01768-0 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Alireza Chamanzar ◽

Marlene Behrmann ◽

Pulkit Grover

Keyword(s):

Center Of Mass ◽

Cost Effective ◽

Human Head ◽

Head Model ◽

Cortical Function ◽

Scalp Eeg ◽

Localization Algorithms ◽

Important Benefit ◽

Eeg Recordings ◽

Detection And Localization

AbstractA rapid and cost-effective noninvasive tool to detect and characterize neural silences can be of important benefit in diagnosing and treating many disorders. We propose an algorithm, SilenceMap, for uncovering the absence of electrophysiological signals, or neural silences, using noninvasive scalp electroencephalography (EEG) signals. By accounting for the contributions of different sources to the power of the recorded signals, and using a hemispheric baseline approach and a convex spectral clustering framework, SilenceMap permits rapid detection and localization of regions of silence in the brain using a relatively small amount of EEG data. SilenceMap substantially outperformed existing source localization algorithms in estimating the center-of-mass of the silence for three pediatric cortical resection patients, using fewer than 3 minutes of EEG recordings (13, 2, and 11mm vs. 25, 62, and 53 mm), as well for 100 different simulated regions of silence based on a real human head model (12 ± 0.7 mm vs. 54 ± 2.2 mm). SilenceMap paves the way towards accessible early diagnosis and continuous monitoring of altered physiological properties of human cortical function.

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Zero-crossing patterns reveal subtle epileptiform discharges in the scalp EEG

Scientific Reports ◽

10.1038/s41598-021-83337-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Jan Pyrzowski ◽

Jean- Eudes Le Douget ◽

Amal Fouad ◽

Mariusz Siemiński ◽

Joanna Jędrzejczak ◽

...

Keyword(s):

Normal Subjects ◽

Intracranial Eeg ◽

Zero Crossing ◽

Temporal Precision ◽

Scalp Eeg ◽

Epileptiform Discharges ◽

Interictal Epileptiform Discharges ◽

Eeg Recordings ◽

Patients With Epilepsy ◽

Low Amplitude

AbstractClinical diagnosis of epilepsy depends heavily on the detection of interictal epileptiform discharges (IEDs) from scalp electroencephalographic (EEG) signals, which by purely visual means is far from straightforward. Here, we introduce a simple signal analysis procedure based on scalp EEG zero-crossing patterns which can extract the spatiotemporal structure of scalp voltage fluctuations. We analyzed simultaneous scalp and intracranial EEG recordings from patients with pharmacoresistant temporal lobe epilepsy. Our data show that a large proportion of intracranial IEDs manifest only as subtle, low-amplitude waveforms below scalp EEG background and could, therefore, not be detected visually. We found that scalp zero-crossing patterns allow detection of these intracranial IEDs on a single-trial level with millisecond temporal precision and including some mesial temporal discharges that do not propagate to the neocortex. Applied to an independent dataset, our method discriminated accurately between patients with epilepsy and normal subjects, confirming its practical applicability.

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