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Background and Objectives: Psychological state of a person can change under conditions of cognitive load. Excessive cognitive load can lead to distress, which reduces performance. Diagnosis of changes in the psychophysical state in the process of performing cognitive tasks is important for human health and increasing the efficiency of his work. Therefore, the purpose of the study is to develop a hardware and software complex for diagnosing the psychophysiological state of a person in the process of solving cognitive problems. Materials and Methods: Electroencephalogram signals were recorded using a developed device and a certified standard recorder during a biological experiment. A comparison was made of the diagnostic capabilities of the developed hardware-software complex and a serial device. Results: A hardware-software complex has been developed for diagnosing the psychophysiological state of a person in the process of solving cognitive problems using an electroencephalogram signal. The developed system has shown sensitivity and specificity values close to those of the serial recorder. Using the developed complex, the electroencephalogram channels suitable for diagnosing the psychophysical state have been selected. Conclusion: The developed hardware-software complex can be used to diagnose the psychophysiological state of a person in the process of performing cognitive tasks.

Background and Objectives: the coupling of EEG signals during an epileptic seizure in patients during coma is being studied. Materials and Methods: the analysis of the applicability of the method of detecting the interaction between oscillatory systems based on the phase dynamics modeling to EEG signals during an epilepsy seizure in comatose patients is carried out. Results: a method of preliminary filtering of EEG signals has been proposed and the values of the method parameters have been selected, which allow obtaining reliable estimates of directional coupling at a significance level of 0.05. As an example, the analysis of the couplings between EEG signals of two patients with the mentioned pathologies was carried out using the method of the coupling estimation developed in this work.

Background and Objectives: Index equal to the spectral power of the low-frequency oscillations from the time series of the time intervals between the hearts contractions are often used when investigating the cardiovascular system. Experimental studies have shown that this spectral index was a preclinical marker of cardiovascular diseases, including arterial hypertension and diabetes. However, physiological understanding of this index, in particular, its relation to the tone of autonomic control is still largely not understood. Materials and Methods: This problem was studied using mathematical models of the cardiovascular system, which simulated a healthy subject and an arterial hypertension patient. Conclusion: The decrease in the power of low-frequency oscillations in the time-series of the time intervals between the heart contractions in arterial hypertension patients was due to decreased dynamic range of the arterial baroreceptors.

Background and Objectives: The development of methods for the analysis of non-stationary signals of biological nature makes it possible to solve a number of fundamental and applied problems. The use of these methods is promising for the diagnosis and prevention of diseases of the cardiovascular system. The creation of the device makes it possible to detect diseases at an early stage. However, this requires the development of methods for analyzing non-stationary signals of biological nature in real time. Therefore, the purpose of the study is the method for diagnosing the phase chain of autonomic control of blood circulation in real time. Materials and Methods: Test realizations of instantaneous phase differences were created, repeating the statistical properties of real data recorded from people. A comparison of the sensitivity of the developed and known methods for different values of the input parameters was carried out. The complexity of the two methods was estimated. Results: A method was developed for diagnosing the phase chains of autonomic control of blood circulation in real time. The methods showed similar sensitivity values. The developed method has less complexity in comparison with the known method. Conclusion: The developed method can be used to diagnose the phase synchronization of the autonomic regulation circuits of the heart and blood vessels in real time.

Background and Objectives: Due to the development of methods for analyzing signals of autonomous blood circulation control, cardiovascular system disorders can be diagnosed today in the early stages. It is promising to use specialized devices for personalized diagnosis of the cardiovascular system and monitoring its state. Research on autonomous blood circulation control systems is a complex problem both from the point of view of physiology and radiophysics. Its solution requires the development of methods and specialized devices for the analysis and registration of signals from the cardiovascular system. Therefore the object of research is the development of a photoplethysmogram sensor with a digital communication channel with a band of 0.05-30 Hz, recording the signals from the autonomous blood circulation monitoring system. Materials and Methods: To compare the level of noise and nonlinear distortions in the center of the frequency range of interest to us (at a frequency of 0.1 Hz), the power spectra of the signals were analyzed, and the coherence function was also calculated. Results: a prototype of a device for recording and analyzing a photoplethysmogram signal was developed and implemented, which makes it possible to register the signals from the circuits of autonomous blood circulation regulation. A comparative analysis of the developed device with a serial analog sensor was carried out, which demonstrated the advantages of the developed device. Conclusion: The developed broadband digital sensor can be used in wearable devices to diagnose the functional state of the cardiovascular system based on the analysis of synchronization between the circuits of autonomous regulation of blood circulation.

Objective—Heart rate variability (HRV) and photoplethysmographic waveform variability (PPGV) are available approaches for assessing the state of cardiovascular autonomic regulation. The goal of our study was to compare the frequency-domain features and low-frequency (LF) synchronization of the PPGV and HRV with increasing severity of cardiovascular diseases. Methods—Our study included 998 electrocardiogram (ECG) and finger photoplethysmogram (PPG) recordings from subjects, classified into five categories: 53 recordings from healthy subjects, aged 28.1 ± 6.2 years, 536 recordings from patients with hypertension (HTN), 49.0 ± 8.8 years old, 185 recordings from individuals with stable coronary artery disease (CAD) (63.9 ± 9.3 years old), 104 recordings from patients with myocardial infarction (MI) that occurred three months prior to the recordings (PMI) (65.1 ± 11.0 years old), and 120 recordings from study subjects with acute myocardial infarction (AMI) (64.7 ± 11.5 years old). Spectral analyses of the HRV and PPGV were carried out, along with an assessment of the synchronization strength between LF oscillations of the HRV and of PPGV (synchronization index). Results—Changes in all frequency-domain indices and the synchronization index were observed along the following gradient: healthy subjects → patients with HTN → patients with CAD → patients with PMI → patients with AMI. Similar frequency-domain indices of the PPGV and HRV show little relationship with each other. Conclusions—The frequency-domain indices of the PPGV are highly sensitive to the development of any cardiovascular disease and, therefore, are superior to the HRV indices in this regard. The S index is an independent parameter from the frequency-domain indices. [ABSTRACT FROM AUTHOR]