Analysis two types of K complexes on the human EEG based on classical continuous wavelet transform.

In our work, we compare EEG time-frequency features for two types of K-complexes detected in volunteers performing the monotonous psychomotor test with their eyes closed. Type I K-complexes preceded spontaneous awakenings, while after type II K-complexes, subjects continued to sleep at least for 10 s after. The total number of K-complexes in the group of 18 volunteers was 646, of which of which type I K-complexes was 150 and type II K-complexes was 496. Time-frequency analysis was performed using continuous wavelet transform. EEG wavelet spectral power was averaged upon several brain zones for each of the classical frequency ranges (slow wave, δ, θ, α, ß1, ß2, γ bands). The low-frequency oscillatory activity ( δ-band) preceding type I K-complexes was asymmetrical and most prominent in the left hemisphere. Statistically significant differences were obtained by averaging over the left and right hemispheres, as well as projections of the motor area of the brain, p<0.05. The maximal differences between the types I and II of K-complexes were demonstrated in δ-, θ-bands in the occipital and posterior temporal regions. The high amplitude of the motor cortex projection response in ß2-band, [20;30] Hz, related to the sensory-motor modality of task in monotonous psychomotor test. The δ-oscillatory activity preceding type I K-complexes was asymmetrical and most prominent in the left hemisphere may be due to the important role of the left hemisphere in spontaneous awakening from sleep during monotonous work, which is an interesting issue for future research.

EEG biomarkers of activation of the lymphatic drainage system of the brain during sleep and opening of the blood-brain barrier.

The lymphatic drainage system of the brain (LDSB) is the removal of metabolites and wastes from its tissues. A dysfunction of LDSB is an important sign of aging, brain oncology, the Alzheimer's and Parkinson's diseases. The development of new strategies for diagnosis of LDSB injuries can improve prevention of age-related cerebral amyloid angiopathy, neurodegenerative and cerebrovascular diseases. There are two conditions, such as deep sleep and opening of the blood-brain-barrier (OBBB) associated with the LDSB activation. A promising candidate for measurement of LDSB could be electroencephalography (EEG). In this pilot study on rats, we tested the hypothesis, whether deep sleep and OBBB can be an informative platform for an effective extracting of information about the LDSB functions. Using the nonlinear analysis of EEG dynamics and machine learning technology, we discovered that the LDSB activation during OBBB and sleep is associated with similar changes in the EEG θ-activity. The OBBB causes the higher LDSB activation vs. sleep that is accompanied by specific changes in the low frequency EEG activity extracted by the power spectra analysis of the EEG dynamics combined with the coherence function. Thus, our findings demonstrate a link between neural activity associated with the LDSB activation during sleep and OBBB that is an important informative platform for extraction of the EEG-biomarkers of the LDSB activity. These results open new perspectives for the development of technology for the LDSB diagnostics that would open a novel era in the prognosis of brain diseases caused by the LDSB disorders, including OBBB.

Infections, Pandemics, and Sleep Disorders.

Studies of the neurological symptoms and signs associated with the acute and late phases of infectious diseases are important in pandemic conditions. The novel coronavirus infection (COVID-19) pandemic has increased the number of patients with sleeplessness, this being an adverse prognostic factor for infections. This review addresses the factors and mechanisms of sleep impairments and their relationship with inflammation and immune system dysfunction in infectious diseases. In particular, impairments to the functioning of the melatoninergic system are discussed as the cause of sleeplessness during pandemics. The relevance of developing measures for rehabilitating patients, particularly use of Sonnovan to restore normal sleep, which plays a fundamental role in supporting people's mental and physical health, is emphasized.

[Infections, pandemics and sleep disorders]. / Infektsii, pandemii i narusheniya sna.

The study of neurological symptoms and signs connected with acute and long-term periods of infectious diseases is relevant during pandemics. The COVID-19 pandemic has increased the number of patients suffering from insomnia. Sleep disturbance is an unfavorable prognostic factor for infections. Risk factors and mechanisms of sleep disturbance, their relationship with inflammation and dysfunction of the immune system in infectious diseases are presented. In particular, dysfunction of the melatonergic system as the cause of insomnia during pandemics is considered. The authors highlight the relevance of measures aimed at the rehabilitation of patients, in particular, the use of sonnovan to restore normal sleep, which is important for a person's mental and physical health.

Synchronization of infra-slow oscillations of brain potentials with respiration.

We study the synchronization of infra-slow oscillations in human scalp electroencephalogram signal with the respiratory signal. For the cases of paced respiration with a fixed frequency and linearly increasing frequency, we reveal the phase and frequency locking of infra-slow oscillations of brain potentials by respiration. It is shown that for different brain areas, the infra-slow oscillations and respiration can exhibit synchronous regimes of different orders.