RU2252692C2 - Method and device for studying functional state of brain and method for measuring subelectrode resistance - Google Patents

Method and device for studying functional state of brain and method for measuring subelectrode resistance Download PDF

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RU2252692C2
RU2252692C2 RU2003123601/14A RU2003123601A RU2252692C2 RU 2252692 C2 RU2252692 C2 RU 2252692C2 RU 2003123601/14 A RU2003123601/14 A RU 2003123601/14A RU 2003123601 A RU2003123601 A RU 2003123601A RU 2252692 C2 RU2252692 C2 RU 2252692C2
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amplifier
brain
activity
connected
current
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RU2003123601/14A
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RU2003123601A (en
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С.М. Захаров (RU)
С.М. Захаров
А.А. Скоморохов (RU)
А.А. Скоморохов
Б.Е. Смирнов (RU)
Б.Е. Смирнов
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ОБЩЕСТВО С ОГРАНИЧЕННОЙ ОТВЕТСТВЕННОСТЬЮ НАУЧНО-ПРОИЗВОДСТВЕННО-КОНСТРУКТОРСКАЯ ФИРМА "Медиком МТД"
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Abstract

FIELD: medicine; medical engineering.
SUBSTANCE: method involves recording multichannel electroencephalogram, electrocardiogram record and carrying out functional test and computer analysis of electrophysiological signals synchronously with multichannel record of electroencephalogram and electrocardiogram in real time mode. Superslow brain activity is recorded, carotid and spinal artery pools rheoelectroencephalogram is recorded and photopletysmogram of fingers and/or toes is built and subelectrode resistance of electrodes for recording bioelectrical cerebral activity is measured. Physiological values of bioelectrical cerebral activity are calculated and visualized in integrated cardiac cycle time scale as absolute and relative values of alpha-activity, pathological slow wave activity in delta and theta wave bandwidth. Cerebral metabolism activity dynamics level values are calculated and visualized at constant potential level. Heart beat rate is determined from electrocardiogram, pulsating blood-filling of cerebral blood vessels are determined from rheological indices data. Peripheral blood vessel resistance level, peripheral blood vessel tonus are determined as peripheral photoplethysmogram pulsation amplitude, large blood vessel tonus is determined from pulse wave propagation time data beginning from Q-tooth signal of electrocardiogram to the beginning of systolic wave of peripheral photoplethysmogram. Postcapillary venular blood vessels tonus is determined from constant photoplethysmogram component. Functional brain state is determined from dynamic changes of physiological values before during and after the functional test. Device for evaluating functional brain state has in series connected multichannel analog-to-digital converter, microcomputer having galvanically isolated input/output ports and PC of standard configuration and electrode unit for reading bioelectric cerebral activity signals connected to multichannel bioelectric cerebral activity signals amplifier. Current and potential electrode unit for recording rheosignals, multichannel rheosignals amplifier, current rheosignals generator and synchronous rheosignals detector are available. The device additionally has two-frequency high precision current generator, master input of which is connected to microcomputer. The first output group is connected to working electrodes and the second one is connected to reference electrodes of electrode unit for reading bioelectrical cerebral activity signals. Lead switch is available with its first input group being connected to potential electrodes of current and potential electrodes unit for recording rheosignals. The second group of inputs is connected to outputs of current rheosignals oscillator. The first group of outputs is connected to current electrodes of current and potential electrodes unit for recording rheosignals. The second group of outputs is connected to inputs of synchronous detector of rheosignals. Demultiplexer input is connected to output of synchronous detector of rheosignals and its outputs are connected to multichannel rheosignals amplifier inputs. Outputs of multichannel bioelectrical cerebral activity signals amplifier, multichannel rheosignals amplifier and electrophysiological signal amplifier are connected to corresponding inputs of multichannel analog-to-digital converter. Microcomputer outputs are connected to control input of lead switch, control input of multichannel demultiplexer, control input of multichannel analog-to-digital converter and synchronization inputs of current rheosignals oscillator and synchronous detector of rheosignals. To measure subelectrode resistance, a signal from narrow bandwidth current generator of frequency f1 exceeding the upper frequency fup of signals under recording is supplied. A signal from narrow bandwidth current generator of frequency f2≠ f1>fup is supplied to reference electrode. Voltages are selected and measured at output of each amplifier with frequencies of f1, f2 - Uf1 and Uf2 using narrow bandwidth filtering. Subelectrode resistance of each working electrode is determined from formula Zj=Ujf1 :(Jf1xKj), where Zj is the subelectrode resistance of j-th electrode, Ujf1 is the voltage at output from j-th amplifier with frequency of f1, Kj is the amplification coefficient of the j-th amplifier. Subelectrode resistance of reference electrode is determined from formula ZA=Ujf2 :(Jf2xKj), where ZA is the subelectrode resistance of reference electrode, Ujf2 is the voltage at output from j-th amplifier with frequency of f2, Jf2 is the voltage of narrow bandwidth current oscillator with frequency of f2.
EFFECT: wide range of functional applications.
15 cl, 10 dwg

Description

The invention relates to medicine and can be used to monitor the condition of patients with impaired cerebral circulation and for the differential diagnosis of epilepsy and epileptiform manifestations.

Paroxysmal conditions of the nervous system relate to nervous diseases that are widespread, especially in developed countries, and tend to increase. Diagnosis of these diseases is usually carried out according to a thorough clinical examination of patients, including the use of electrophysiological methods, angiography, fluoroscopy, nuclear magnetic resonance imaging, positron emission tomography and other instrumental approaches. To clarify the diagnosis, a clinical and biochemical analysis of blood and other biological fluids is often used for the content of excitatory and inhibitory neurotransmitters and neuropeptides or their metabolic products: glutamate, GABA, serotonin, dopamine, monoamine oxidase, endorphin, etc. (see, for example, the patent of the Russian Federation №2112243, IPC 7 G 01 N 33/53, C 12 Q 1/04, A 61 K 39/00) However, the use of these methods to assess the functional state of the brain and the organism does not allow one to determine the extent of involvement of certain metabolic regulatory systems in the pathogenesis of the disease, which is very important for determining treatment tactics, requires large time and economic costs for research, does not have a sufficient level of specificity for each nosological form, practically does not make it possible to identify a predisposition (risk group), to diagnose diseases at an early stage stages.

A known method for determining the bioelectric activity of the brain, including the imposition on the patient’s head of measuring electrodes above the brain and a zero electrode at a certain distance from the brain, amplifying the signals from the measuring electrodes in two stages: at the first stage, the biopotential from each measuring electrode is fed to one input of the corresponding differential amplifier, at the second input of which the biopotential is supplied from the zero electrode, at the second stage, the output signal of each differential amplifier compares with an averaged output signal of differential amplifiers of adjacent measuring electrodes (see application of Great Britain No. 1501803, IPC 3 А61В 5/04, NKI G1N, A3R, publ. 1979). This method, due to the lack of the ability to measure subelectrode resistances, does not have sufficient accuracy of recording the ultra slow (less than 1 Hz) bioelectrical activity of the brain, which estimates the magnitude of cerebral energy consumption. Therefore, such a study of the functional state of the brain is not very informative for the differential diagnosis of epilepsy and epileptiform manifestations.

In the patent of the Russian Federation No. 2007116, IPC 5 A 61 B 5/04, publ. 1994, a method is described for recording a level shift in the constant electric potential of the brain, used in assessing the stability of a functional state, in the diagnosis of neurosis and mental illness. The method is as follows. A pair of recording electrodes is mounted on the subject’s head over a given area of the brain. The electrodes are connected to an electric voltage amplifier, the output of which is read at the beginning and end of the shear caused by external influence, the values of the constant electric potential and compare them with each other. To exclude the influence of instability of the interelectrode skin potential, the amplifier input is short-term shunted by the reference resistance and a comparison is made between the decrease in resistance that occurs during short-term shunting of the amplifier input at the beginning and end of the shift. If the decrease in gain is the same, then it is believed that the effect of the skin potential does not affect, and the result is recorded. If the decrease in gain at the beginning and end of the shift is different, then it is believed that the results are distorted by the instability of the skin potential, and registration is not carried out. The disadvantage of this method of assessing the functional state of the brain is its limited applicability, the lack of the possibility of differential diagnosis of cerebral circulation, low information content and low accuracy due to the instability and differences in the electrode resistance.

Patent of the Russian Federation No. 2187958, IPC 7 A 61 B 5/04, publ. 2002, a method for studying the state of cerebral vessels, including local cold exposure and rheoencephalography, characterized in that local cold exposure is carried out in the projection of the basin of the vessels of the internal carotid artery by a heat exchanger with a temperature t ° = 10 ± 2 ° C for 10 min, is protected moreover, rheoencephalography is carried out before, immediately and after 10 and 20 minutes after cold exposure. This method has limited use and is unsuitable for the differential diagnosis of epilepsy and epilepiform manifestations.

From the description of the patent of the Russian Federation No. 2189776, IPC 7 A 61 B 5/0476, publ. 2002, a known method for diagnosing and predicting the development of epilepsy in patients with a preclinical stage of the disease. An electroencephalogram is recorded in the patient's state of passive wakefulness. Using cross-correlation analysis process fragments of EEG with a duration of not more than one minute, which do not contain paroxysmal activity. The cross-correlation coefficients (CCR) of alpha activity between the leads of the left frontal and left occipital regions are obtained. The obtained values of CKr in the range from –1.00 to -0.35 indicate the patient’s health, with values of CKr from -0.34 to 0.00, the preclinical stage of epilepsy is diagnosed, and with values of CKr from 0.01 to 1.00 - clinical stage of epilepsy. The method improves the accuracy of diagnosis of the development of epilepsy. The disadvantage of this method is of limited use and does not allow, due to low information content, to carry out differential diagnosis of cerebrovascular disorders.

A known method for determining a violation of the blood supply to the head (see patent of the Russian Federation No. 2159075, IPC 7 A 61 B 5/05, publ. 2000), in accordance with which differential rheograms are recorded from the neck, chest, arms. Measure their amplitude-time characteristics. The volume of blood flow to the head is calculated as the difference in the volume of blood flow in the areas of the chest - neck and chest - arms. The envelope rheogram is recorded on the chest - neck section and the amplitudes of its venous systolic and main waves are measured. Calculate their ratio. An ultrasound dopplerogram of blood flow through the right atrioventricular opening of the heart is recorded. It measures the average blood flow velocity during early filling of the right ventricle of the heart and systole of the right atrium. Calculate their ratio. Violation of the blood supply to the head is determined by the calculated values. The disadvantage of this method is that it allows to identify pathological disorders only with their clinical severity and is not very effective in prenosological diagnosis.

From the description of the patent of the Russian Federation No. 2188575, IPC 7 A 61 B 5/0476, G 01 N 33/53, publ. 2002, there is a known method for diagnosing and predicting the development of epilepsy in patients with a preclinical stage of the disease, including EEG monitoring, processing of the obtained EEG by the method of fractal analysis and obtaining values of fractal dimension (FR), calculation of the values of the paraximal activity test (PAT) by the content in the blood auto-antibodies to a quisqualate-binding membrane protein, calculation of the epilepsy index (IE) by the formula IE = PAT × FR and diagnosis of the clinical stage of epilepsy with IE = 132.5 ± 5.32, no signs of epi epsii at values IE = 45.05 ± 3.31 and preclinical epilepsy at intermediate values of IE. This method allows you to identify the preclinical stage of epilepsy, but is not very informative for the differential diagnosis of epilepsy and epileptiform manifestations.

From the patent of the Russian Federation No. 2103912, IPC 6 A 61 B 5/0476, publ. 1998, there is a known method for examining the brain, according to which an electroencephalogram is taken before and after the presentation of a stimulus, the EEG power spectrum or the synchronism coefficient of electrical processes at each electrode location with respect to neighboring ones is calculated. The change in the magnitude of the obtained values after the stimulus is determined and the results of the calculations are presented in the form of a topographic map. In addition, the temperature is measured at the points of location of the electrodes, its difference is calculated and entered into the map. This method allows simultaneously with the measurement and study of electrical processes, measure and study the thermal field of the head. The disadvantage of this method is the lack of differential diagnosis of cerebrovascular accidents, the inability to distinguish between epilepsy and epileptiform manifestations.

A known method for diagnosing the degree of psychophysiological maladaptation in patients with initial forms of chronic cerebrovascular pathology (see patent of the Russian Federation No. 2154979, IPC 7 A 61 B 5/04, 5/0476, publ. 2000). This method is as follows. A patient who is in a state of relaxed wakefulness with his eyes closed is made multi-channel EEG recording according to the standard method, having 19 or more electrodes for tracking artifacts. At the same time, a computer-aided spectral analysis of artifact-free EEG fragments is carried out with an assessment of the power of the spectrogram in the frequency bands alpha (8 ... 12 Hz), beta (12 Hz and higher), theta (4 ... 8 Hz) and delta ( 0 ... 4 Hz) activity. With a value of the absolute power of alpha activity of more than 10 μV 2 , or more than 80 μV 2 , and / or with values of the power of alpha activity of more than 50%, a significant degree of psychophysiological maladaptation is diagnosed. The described method allows you to objectify in patients with initial forms of vascular diseases of the brain a significant psychophysiological maladaptation, which is an important pathogenetic factor in the development of pathology. The disadvantage of this method is the low efficiency in determining the causes of cerebrovascular accident and in the differential diagnosis of epilepsy and epileptiform manifestations.

Closest to the claimed method for studying the functional state of the brain by most coinciding signs is a method for studying the individual characteristics of the regulation of the physiological functions of the human body, protected by the patent of the Russian Federation No. 2185088, IPC 7 A 61 5/00, 5/04, publ. 2002. A method for studying the individual characteristics of the regulation of physiological functions includes recording an electroencephalogram (EEG), an electrocardiogram (ECG) pneumogram, measuring blood pressure (BP) and conducting seven functional breathing tests. Features of the regulation of physiological functions are determined by indicators of external respiration and gas exchange, PACO 2 , RAO 2 , pneumograms, the nature and rate of occurrence of changes in ECG, blood pressure, EEG, the latent period of the motor reaction, the rate of production of non-respiratory conditioned reflexes. The first test, 1-2-minute non-dosed intensity hyperventilation, is carried out taking into account the sensations caused by changes in cerebral circulation, dizziness, mild headache, veils in front of the eyes, changes in the central nervous system, manifested in the form of sensory or motor disorders, in the form of paresthesia , numbness, stiffness, tension, trembling, as well as vegetative shifts in the form of a sensation of warmth, palpitations, sweating, dry mouth, allowing to identify physiological functions: cardiovascular stye, respiratory, nervous system, involved in the development of hyperventilation syndrome. The second test - rigid hyperventilation is carried out for 2.5-3.5 minutes, during which the subject is given commands to maintain the level of ventilation, carried out in order to identify people who are sensitive to hyperventilation, registering the speed of sensations and their nature. The third test, isocapnic hyperventilation, which ensures the maintenance of a stable level of RSO 2 in the subjects, is carried out to identify subjects with a predominance of neurogenic factor in the regulation of functions. The fourth test is breath holding at the level of a calm breath. The fifth test is breath holding at the level of a normal exhalation. Sixth test - breath holding on inhalation after arbitrary hyperventilation. In all three breath-holding samples, the time from the start of the breath-hold until the first impulse to breathe (phase 1) to the resumption of breathing (phase 2), as well as the total time of breath-holding, is determined. In the first phase, the individual sensitivity of the subjects to the totality of humoral CO 2 and O 2 and neurogenic factors is evaluated; in the second phase, the ability to volitional efforts is evaluated. The seventh test - hypoventilation - breathing mode, in which the subject breathes at least 10 minutes in rhythm two breaths per minute without depth restriction, after a preliminary respiratory training, the duration of which is individually determined. The seven samples listed make it possible to identify the individual sensitivity of the subjects to humoral and neurogenic factors, the first and second tests with hyperventilation to the degree of PACO 2 fall and neurogenic shifts expressed to varying degrees, the third test with hyperventilation to only neurogenic factors, the fourth and fifth tests with breath holding - to the accumulation of CO 2 , a decrease in RAO 2 and neurogenic factors, the sixth test with a breath hold - to a decrease in RAO 2 , the seventh test - to a decrease in RAO 2 , the accumulation of PACO 2 , neurogenic factors, training respiration and the ability to establish a new, more effective breathing stereotype. The achieved result consists in the possibility of obtaining the most complete information about the formation of the physiological reactions of the body to voluntary control of respiration and its adaptive capabilities, targeted influence on the functional state of the body, increasing the mental and physical performance of healthy people, increasing the efficiency of adaptation to changing environmental conditions, training and establishing new effective breathing stereotype. The disadvantage of the prototype method is that it is applicable for studying the individual characteristics of healthy people and is ineffective in establishing the causes of cerebrovascular accident, in the differential diagnosis of epilepsy and epileptiform manifestations, in identifying the initial manifestations of cerebrovascular disorders and predicting their development.

The problem solved by the invention is to increase efficiency in determining the causes of cerebrovascular accident and in the differential diagnosis of epilepsy and epileptiform manifestations, identifying the initial manifestations of cerebrovascular disorders and predicting their development.

The solution to this problem is achieved by the fact that in a method for studying the functional state of the brain, including multi-channel recording of an electroencephalogram (EEG), electrocardiogram (ECG), conducting a functional test and computer analysis of electrophysiological signals, in addition, synchronously with multi-channel recording of EEG and ECG in real time register ultra-slow brain activity, record rheoelectroencephalogram (REG) in the basins of the carotid and vertebral arteries and photoplethysmogram (FIG) of the fingers and / or feet and the measurement of the electrode resistance of the electrodes to measure the bioelectrical activity of the brain, at the same time on a single cardiocycle time scale, i.e. in conjunction with each of the automatically recognized cardiocycles, physiological indicators of the bioelectrical activity of the brain are calculated and visualized - the absolute and relative values of the alpha activity power, pathological slow-wave activity in the range of delta and theta waves, an indicator of the level of brain metabolic activity by the constant component of the EEG, the heart rate by ECG, the pulse rate of blood vessels in the brain according to the rheographic indexes of REG, peripheral cerebral vascular resistance index (PPSS), peripheral vascular tone index in the form of an amplitude of peripheral PPG pulsation, the main vessels tonus by the pulse wave propagation time from the Q wave of the ECG signal to the beginning of the peripheral PPG systolic wave, and the DC component of the post-capillary-venous vessels tone FIG, and the differential diagnosis of epilepsy and epileptiform manifestations is carried out according to the dynamics of changes in physiological parameters before, during I and after a functional test. To determine the functional state of the brain, a functional test is carried out for hyperventilation and, if after the start of the test, a decrease in the rheographic index of REG is observed by more than 20%, and then paroxysmal manifestations on the EEG are observed in the form of a sharp increase in the ratio of pathological slow-wave waves in delta and theta -range to alpha activity, then a potential cause of paroxysmal manifestations on the EEG formulate vascular disorders of the brain. If a decrease in the rheographic index of REG and the appearance of paroxymal manifestations on the EEG is accompanied by a shift in the level of the constant potential of super slow brain activity, then it is concluded that there is an effect of the vascular factor on paroxysmal manifestations, accompanied by metabolic changes. If a decrease in the Rheographic index of REG and the appearance of paroxysmal manifestations on the EEG is not accompanied by a significant decrease in peripheral blood flow by PPG, then the insufficiency of regulatory processes to compensate for a decrease in peripheral blood flow and redistribution of the general blood flow to vital organs is formulated as a possible cause of vascular disorders of the brain. If the decrease in the rheographic index of REG and the appearance of paroxysmal manifestations on the EEG coincide, then it is additionally concluded that there is a focus of pathological activity that determines the inadequacy of regional cerebral blood flow. If before the functional test for hyperventilation, EEG disorganization, a decrease in pulse blood supply and an increase in REG tone were observed, and during the test, normalization of cerebral blood flow indicators was observed, expressed in an increase in pulse blood supply, a decrease in peripheral resistance of cerebral vessels, and normalization of EEG, expressed in an increase in the level of alpha activity with the preservation of zonal differences in the fronto-occipital regions, a decrease in the ratio of pathological slower wave waves in the delta and theta ranges for alpha activity, then formulate the assumption of the presence of cerebrovascular disorders associated with a violation of the gas composition of the blood in the initial background state. If a functional test for hyperventilation is carried out and during the test the extrasystoles are observed on the ECG signal and they are preceded by paroxysms on the synchronously recorded EEG signals, then a conclusion is drawn about the cerebrogenic nature of heart rhythm disturbances if there is no causal-time relationship between paroxysms on the EEG and extrasystoles on the ECG , then a conclusion is drawn about the cardiogenic nature of heart rhythm disturbances. A long passive orthostatic test is performed, and if the patient has a synocopal state during the test, then with a pronounced bradycardia or asystole by ECG before the onset of the synocopal state and a decrease in cerebral blood flow by REG, the cardioinhibitory cause of the syncope state is diagnosed, with the previous synocopal state of pronounced signs deposition of blood in the extremities by PPG and a decrease in cerebral blood flow by REG and the absence of significant smart sheniya heart rate ECG diagnosed vazodepresivnuyu cause syncope, and when the preceding paroxysms syncope EEG and no significant reduction in heart rate and ECG pronounced signs of blood in the extremities of the Deposit of FIGs diagnosed type convulsive syncope.

A device for studying the functional state of the brain is an independent object of the invention.

Known electroencephalograph, protected by USSR patent N 880241, IPC 3 . АВВ 5/04 (application of Germany N 2727583 dated 06/20/77), containing measuring electrodes placed on the patient’s head, lead selector made in the form of a head image with switches with indicator lights placed on it, and signal amplifiers, the inputs of which are through the lead selector is connected to the measuring electrodes, and the output signals control the recorders. This electroencephalograph provides the visibility of connecting the measuring electrodes to the inputs of the amplifiers, thereby reducing the likelihood of their erroneous connection. The disadvantages of such an electroencephalograph include the lack of the possibility of an operative analysis of electroencephalograms, the inability to detect violations of cerebral blood flow.

A device for assessing pathological changes in the systemic activity of the human brain, including a set of sensors applied to the human head and / or connected to deep electrodes, a multi-channel amplifier of sensor signals with the number of channels corresponding to the number of sensors, a unit for simultaneous conversion of signals from continuous to discrete, block for statistical processing of the obtained data and block volume playback (see US patent No. 4736751, IPC 5 A 61 5/04, publ. 1988). Such a device does not provide identification of the causes of cerebrovascular accident and is not effective enough for the differential diagnosis of epilepsy and eleptiform manifestations.

From the patent of the Russian Federation No. 2177716, IPC 7 A 61 B 5/0476, publ. In 2002, a device for assessing pathological changes in the systemic activity of the brain is known, which includes a set of sensors placed on a person’s head and / or connected to deep electrodes and / or located at some distance from the head, a multi-channel amplifier of sensor signals, for example, an electroencephalograph , with the number of channels corresponding to the number of sensors, a signal conversion unit, for example, conversion from continuous to discrete, a unit for measuring the statistical relationship between processes, a unit of measurement the rhenium of the dimension of the space of the displayed processes corresponding to the aggregate statistical properties of the relationships between the measured processes, a unit for calculating the coordinates and / or values of the radius vectors of the displayed processes, a unit for visualizing the spatial distribution of the radius vectors of the displayed processes, for example, a plotter or graphic display, a storage device, a difference measurement unit parameters of the spatial distributions of the radius vectors of the displayed processes, the visualization block differences in integrative activity of the patient’s brain, test presentation unit and synchronization unit. The device allows to reliably identify the degree and nature of persistent pathological abnormalities in the systemic activity of the human brain, determine their localization and the nature of the disorders, quantify the degree of pathological abnormalities associated with performing tests or with any changes in the functional state of the brain. The disadvantage of this device for assessing pathological changes in the systemic activity of the brain is its relatively low efficiency in the differential diagnosis of epilepsy and eleptiform manifestations, the inability to diagnose the cause of cerebrovascular accident.

Device for recording, recording and analysis of electrophysiological signals, protected by the patent of the Russian Federation No. 2102004, IPC 6 A 61 V 5/04, publ. 1998, contains a series-connected electrode block, a selective multichannel amplifier, a multiplexer, an analog-to-digital converter, a control and preprocessing device, a galvanic separation unit, an interface unit, and a personal computer. The power circuits of the multichannel amplifier are connected to the output buses of the emergency current protection block, the first group of inputs of which is connected to the electrodes, and the second to the output buses of the power source. This device is not effective in the differential diagnosis of epilepsy and eleptiform manifestations due to the lack of the ability to measure brain impedance simultaneously with the collection of signals of brain bioelectrical activity and the control of sub-electrode resistances.

Closest to the claimed device for studying the functional state of the brain is a device for studying the biological activity of the brain, containing a block of discharge electrodes, an electrocardiogram sensor, a patch panel made in the form of an image of the head with sockets for connecting the discharge electrodes, a multi-channel preamplifier, the inputs of which are connected to the corresponding sockets for connecting the patch panel, and the outputs with the corresponding information outputs with lead assignments, an electrocardiogram signal amplifier, the outputs of which are connected to the corresponding connection sockets of the patch panel, an electrode impedance control unit, a multi-channel selective amplifier, an analog-to-digital converter, a sound stimulus generator, a visual stimulus generator and a computer with a magnetic disk drive, a display and by a printing device, an additional unit of measuring electrodes, an intracranial impedance measuring unit, a health monitoring unit with connection block, four-channel differential amplifier, multi-channel analog switch, amplifier with adjustable bias voltage and gain, memory unit, microprocessor, information exchange and interface units, and four-channel analog switch (see patent of the Russian Federation No. 2076625, IPC 6 A 61 B 5/04, publ. 1997 g). This device allows you to take and analyze signals of electroencephalography, electrography and rheoelectroencephalography during one examination session, control the parameters of amplifiers and the impedance of the electrodes, which is especially important in studies involving functional tests.

A device for studying the biological activity of the brain according to the patent of the Russian Federation No. 2076625 adopted as a prototype. Common signs of the claimed device with the prototype are the following:

- purpose - both devices are designed to study the functional state of the brain;

- both devices include functionally similar functional units - an electrode block for collecting signals of brain bioelectrical activity (in the prototype this is a block of discharge electrodes), a block of electrophysiological signal sensors (in the prototype is a cardiac signal sensor), a block of current and potential electrodes for recording re-signals ( in the prototype - a block of measuring electrodes), a multi-channel amplifier of signals of bioelectric activity of the brain (in the prototype - a multi-channel preliminary amplifier), a multi-channel amplifier of reosignals (in the prototype - a multi-channel selective amplifier), multi-channel analog-to-digital converter (in the prototype - a multi-channel analog switch and analog-to-digital converter), an amplifier of electrophysiological signals (in the prototype - an amplifier of an electrocardiogram), microcomputer (in the prototype - microprocessor), a standard configuration PC (in the prototype - a computer with a display and a printing device), a current re-signal generator and a synchronous re-signal detector (in the prototype - b approx impedance measuring intracranial);

- connections of blocks and nodes — an electrode block for collecting signals of brain bioelectrical activity and a block of electrophysiological signal sensors are connected respectively to a multi-channel amplifier of signals of bioelectric activity of the brain and an amplifier of electrophysiological signals (in the prototype they are connected through a patch panel), a multi-channel analog-to-digital converter, microcomputers and PCs of a standard configuration are connected in series (in the prototype, through the data bus and the device is paired Iya, respectively).

The disadvantages of the prototype are the lack of the possibility of synchronous acquisition of electroencephalography and rheoelectroencephalography signals, which reduces the possibility of their mutual correlation, low accuracy of measurement of the electrode resistance, which reduces the accuracy of registration of ultra slow bioelectric activity of the brain. These shortcomings significantly complicate the differential diagnosis of epilepsy and epileptiform manifestations and the identification of the initial manifestations of regulatory disorders.

The problem solved by the invention is to increase the efficiency of the differential diagnosis of epilepsy and epileptiform manifestations, identifying the initial manifestations of regulatory disorders.

The solution to this problem is achieved by the fact that a device for studying the functional state of the brain, containing a multichannel analog-to-digital converter in series, a microcomputer with galvanically isolated input-output ports and a PC of a standard configuration, an electrode block for collecting signals of brain bioelectric activity connected to a multichannel an amplifier of signals of bioelectric activity of the brain, a unit of sensors of electrophysiological signals, connected with an amplifier of electrophysiological signals, a block of current and potential electrodes for recording reosignals, a multichannel amplifier of reosignals, a generator of current reosignals and a synchronous detector of reosignals, additionally contains a two-frequency precision current generator whose input is connected to a microcomputer, the first group of outputs is connected to working electrodes, and the second - with reference electrodes of the electrode block for picking up signals of bioelectrical activity of the brain, lead switch the first group of inputs is connected to the potential electrodes of the current and potential electrode block for recording the re-signals, the second group of inputs is to the outputs of the current rheological signal generator, the first group of outputs is to the current electrodes of the current and potential electrode block to record the re-signals, the second group of outputs is with inputs of a synchronous detector of rheosignals, a demultiplexer, the input of which is connected to the output of a synchronous detector of rheosignals, and outputs with inputs of a multi-channel amplifier For re-signals, the outputs of the multi-channel amplifier of signals of bioelectric activity of the brain, the multi-channel amplifier of re-signals and the amplifier of electrophysiological signals are connected to the corresponding inputs of the multi-channel analog-to-digital converter, the outputs of the microcomputer are connected to the control switch input, the demultiplexer control input, the multi-channel analog-to-digital converter control input synchronization inputs of the current rheosignal generator and the synchronous reo detector signals. The block of sensors of electrophysiological signals contains electrodes for measuring electrical activity of the heart, electrical signals of motor activity of muscles, a photosensor of a pulse wave and a sensor of a respiratory wave. The generator of current rheosignals contains a constant voltage source, the poles of which are connected to the input of the voltage - current linear converter through a controlled switch and a narrow-band voltage amplifier, the output of which is the output of the generator. The synchronous rheosignal detector contains a differential amplifier, a bandpass filter and an inverter connected in series, as well as a controllable switch, switchable inputs are connected to the inverter input and output, the inputs of a synchronous detector are the inputs of a differential amplifier and a control input of a controllable switch, and the output is the output of a controllable switch. A two-frequency precision current generator contains two frequency dividers, the inputs of which are combined and are the driving input of the generator, and the outputs are connected through capacitors with a capacity of 10 ... 20 pF: the first with outputs for connecting working electrodes, the second for connecting reference electrodes. The amplification channel of a multichannel amplifier of signals of bioelectric activity of the brain contains a differential amplifier connected in series, the non-inverting input of which is connected to the input for connecting the corresponding working electrode, and the inverting one through the matching stage with the input for connecting the reference electrode, an amplifier with a constant current gain of unity , and gain in the working frequency band equal to the nominal, and a low-pass filter.

The method of measuring the electrode resistance is an independent object of the invention.

A known method of measuring electric skin resistance, protected by copyright certificate of the USSR No. 1821195, IPC 5 A 61 H 39/00, A 61 V 5/05, publ. 1993, according to which measuring electrodes are applied to the skin, constant-constant stabilized electric current pulses of 200 ... 380 μs duration are passed between them at a current density of 7.1 ... 36.2 μA, the resistance is measured repeatedly at the end of each pulse, and the value of the correction to the measured resistance as the difference between the resistance value in the first measurement and the resistance value in the second 42 seconds after the first measurement, and the resistance value in each subsequent measurement is determined taking into account m of the amendment. This method is not applicable for synchronous measurement of the sub-electrode resistance when registering the biopotentials of the brain and / or electrical signals generated by the heart and / or electrical signals of muscle movements.

According to the method of two-electrode measurement of electrical resistance of biological objects, protected by the USSR copyright certificate No. 1204182, IPC 4 A 61 V 5/05, G 01 R 27/02, publ. 1986, electrodes are placed on the object under study, through which the measuring current is passed and the interelectrode resistance R1 is measured, then the magnitude of the measuring current and the electrode area are changed by a factor of k, provided that the external dimensions of the electrodes are unchanged and the new value of the interelectrode resistance R2 is measured, and the tissue resistance bioobject and sub-electrode resistance R3 calculated by the formulas. This method is also unacceptable for the synchronous measurement of sub-electrode resistances when registering the biopotentials of the brain and / or electrical signals generated by the heart and / or electrical signals of muscle movements.

The technical result from the use of the invention is the provision of the possibility of synchronous measurement of sub-electrode resistances when registering the biopotentials of the brain and / or electrical signals generated by the heart and / or electrical signals of muscle movements.

This result is achieved by the fact that in the method for measuring the sub-electrode resistance when registering the biopotentials of the brain and / or electrical signals generated by the heart and / or electrical signals of muscle movements using differential amplifiers of these signals, a signal from a narrow-band current generator with frequency f 1 exceeding the upper frequency of the recorded signals f Вepx , and a signal from a narrow-band current generator with a frequency f 2 ≠ f 1 > f is fed to the reference electrode Vepx , narrow-band filtering is used to isolate and measure at the output of each amplifier voltage with frequencies f 1 and f 2 - U f1 and u f2 , and the sub-electrode resistance of each of the electrodes is determined taking into account the current values of narrow-band current generators with frequencies f 1 and f 2 - J f1 , J f2 and measured voltages with frequencies f 1 and f 2 - U f1 , U f2 . The electrode resistance of each working electrode is determined by the formula Z j = U jf1: (J f1 × K j ), where Z j is the electrode resistance of the j-th electrode, U jf1 is the voltage at the output of the j-th amplifier with frequency f 1 , J f1 is the current of the narrow-band current generator with a frequency of f 1 , K j is the gain of the j-th amplifier, and the electrode resistance of the reference electrode is determined by the formula: Z A = U jf2: (J f1 × K j ), where Z A is the electrode resistance of the reference electrode A, associated with the j-th amplifier, U jf2 is the voltage at the output of the j-th amplifier with a frequency f 2 , j f2 is the current short-band current generator with a frequency of f 2 .

The applicant has not identified sources containing information about technical solutions identical to the present inventions, which allows us to conclude that they meet the criterion of "novelty."

The applicant is not aware of any publications that would contain information on the influence of the distinguishing features of inventions on the achieved technical result. In this regard, according to the applicant, it can be concluded that the claimed technical solutions meet the criterion of "inventive step".

The invention is illustrated by drawings. Figure 1 shows a structural diagram of a device for studying the functional state of the brain, figure 2 is a functional diagram of an amplifier channel of an amplifier of signals of bioelectrical activity of the brain, figure 3 is a functional diagram of a generator of current rheosignals, figure 4 is a functional diagram of a synchronous rheosignal detector, FIG. 5 is a functional diagram of a two-frequency precision current generator, FIGS. 6 and 8 are examples of recording values of physiological signals: the initial background state is on the left, on the right - with a three-minute hyperventilation, Figs. 7 and 9 show the cardiocycle dynamics of physiological parameters for these examples; Fig. 10 is a functional diagram explaining a method for measuring sub-electrode resistances.

The list of positions in figure 1 - figure 5:

1 - a block of electrodes for picking up signals of bioelectric activity of the brain;

2 - a block of sensors of electrophysiological signals;

3 - block current and potential electrodes for recording rheosignals;

4 - lead switch;

5 - current rheosignal generator;

6 - synchronous rheosignal detector;

7 - a multi-channel amplifier of signals of bioelectric activity of the brain;

8 - amplifiers of electrophysiological signals;

9 - demultiplexer;

10 - multi-channel amplifier rheosignals;

11 - multi-channel analog-to-digital Converter (MACP);

12 - microcomputer with galvanically isolated input-output port;

13 - two-frequency precision current generator;

14 - PC standard configuration;

15 - controlled switch;

16 - low pass filter;

17 - band-pass filter;

18 - controlled switch;

19 - frequency divider with a frequency f 1 ;

20 - frequency divider with a frequency f 2 .

The claimed method for studying the functional state of the brain is implemented as follows. Electrodes are placed on the patient’s head to record the bioelectrical activity of the brain and to record rheographic signals in the carotid and vertebral artery pools, electrodes for detecting electrocardiographic signals, a skin-galvanic reaction sensor, a respiratory wave sensor (if necessary) are attached to the fingers, pulse wave sensors (blood supply). The electrodes and sensors are each connected to a separate input of a multi-channel amplifier connected to a multi-channel analog-to-digital converter, the output of which is connected to a galvanically isolated input / output port of the microcomputer. This allows for simultaneous real-time multichannel recording of the electroencephalogram (EEG), recording of the rheoelectroencephalogram (REG) in the basins of the carotid and vertebral arteries, recording of the electrocardiogram (ECG), photoplethysmogram (PPG) and pneumograms and performing their computer analysis. Simultaneously with multichannel recording of electroencephalograms, rheoelectroencephalograms and electrocardiograms, subelectrode resistances are measured, which provides not only control of the reliability of the contacts of the electrodes with the skin, but also a higher accuracy in determining the parameters of the electroencephalogram, as well as registration of super slow brain activity (SMA) during functional tests. Computer analysis and processing of electrophysiological signals in a PC allows for a single time-cycle cycle time scale, i.e. in relation to each of the automatically recognized cardiocycles, to calculate and visualize the physiological indicators of brain bioelectric activity - the absolute and relative values of the alpha activity power, pathological slow-wave activity in the range of delta and theta waves, an indicator of the dynamics of the level of brain metabolic activity by the constant component of the EEG, the heart rate by ECG, the pulse rate of blood vessels in the brain according to the rheographic indexes of REG, peripheral cerebral vascular resistance index (PPSS), peripheral vascular tone index in the form of an amplitude of peripheral PPG pulsation, the main vessels tonus by the pulse wave propagation time from the Q wave of the ECG signal to the beginning of the peripheral PPG systolic wave, and the DC component of the post-capillary-venous vessels tone FIG, spectral analysis of artifact-free EEG fragments with an estimate of the power of spectrograms in standard frequency ranges. The determination of all these indicators is carried out according to well-known formulas. After turning on and checking the operation of the equipment, a functional test for hyperventilation is carried out in a typical mode. The patient is offered to breathe deeply rhythmically for 3 minutes. The depth of inspiration and the fullness of exhalation should be maximum, respiratory rate within 16 ... 20 per minute. Respiratory parameters are monitored using a respiratory wave sensor. The recording and registration of electrophysiological parameters must be done at least 3 minutes before the sample and at least 5 minutes after its completion. When ascertaining during the test, the presence of a decrease in the rheographic index and paroxysmaximum manifestations on the EEG in the form of a sharp increase in the ratio of pathological slow-wave waves in the delta and theta ranges to alpha activity distinguishes the potential causes of paroxysmal manifestations on the EEG. The differential diagnosis of epilepsy and epileptiform manifestations is as follows. If at first there was a decrease in the rheographic index by more than 20%, and then paroxysmal manifestations are observed, then the cause should be considered with a high probability vascular disorders of the brain. If a decrease in the rheographic index of REG and the appearance of paroxymal manifestations on the EEG is accompanied by a shift in the level of constant potential, then it is concluded that there is an effect of the vascular factor on paroxysmal manifestations, accompanied by metabolic changes. If a decrease in the Rheographic index of REG and the appearance of paroxymal manifestations on the EEG is not accompanied by a significant decrease in peripheral blood flow by PPG, then a potential possible cause of vascular disorders of the brain may be insufficient regulatory processes to compensate for a decrease in peripheral blood flow and the redistribution of total blood flow to vital organs. If the decrease in the rheographic index of REG and the appearance of paroxysmal manifestations on the EEG coincide, then it is additionally concluded that there is a focus of pathological activity that determines the inadequacy of regional cerebral blood flow. If prior to the functional test for hyperventilation, EEG disorganization, a decrease in pulse blood supply and an increase in REG tone were observed, and during the test, normalization of cerebral blood flow indicators was observed, expressed in an increase in pulse blood supply, a decrease in the peripheral resistance of cerebral vessels, and normalization of EEG, expressed in an increase in the level of alpha activity while maintaining zonal differences in the fronto-occipital regions, a decrease in the ratio of pathological medulla wave waves in the delta and theta ranges to alpha activity, then suggest the presence of cerebrovascular disorders associated with a violation of the gas composition of the blood in the initial background state. If a functional test for hyperventilation is carried out and during the test the extrasystoles are observed on the ECG signal and they are preceded by paroxysms on the synchronously recorded EEG signals, then a conclusion is drawn about the cerebrogenic nature of heart rhythm disturbances. If there is no causal-temporal relationship between paroxysms on the EEG and extrasystoles on the ECG, then a conclusion is drawn about the cardiogenic nature of heart rhythm disturbances. To identify the causes of synocopal conditions, a long passive orthostatic test is performed and, if the patient has a synocopal state during the test, then with a pronounced bradycardia or asystole by ECG before the onset of the synocopal state and a decrease in cerebral blood flow by REG, the cardioinhibitory cause of the syncopal state is diagnosed, previous signs of blood deposition of blood in the extremities by PPG and a decrease in brain parameters blood flow by REG, and the absence of a significant decrease in heart rate by ECG, a vasodepressive cause of the syncopal state is diagnosed, and with previous paroxysms on the EEG and the absence of a significant decrease in heart rate by ECG and pronounced signs of blood deposition in the extremities, the convulsive type of syncope is diagnosed.

Synchronous registration of EEG, REG, CMA and other signals with the possibility of a compressed presentation of trends in physiological parameters in a single time scale allows expanding diagnostic capabilities in the study of various diseases and disorders. It allows you to control the correctness of studies (in particular, provoking tests on hyperventilation), take into account the possible influence of the vascular factor in epilepsy, identify patients with an improperly formed respiratory pattern leading to cerebrovascular disorders, provide useful information in the differential diagnosis of syncopal conditions, and investigate the nature of the interactions between body systems for various disorders, provide a more informed choice of therapeutic measures and tsenku their effectiveness.

Due to the importance of aggregate studies that allow simultaneous monitoring of changes in EEG and REG during various functional tests, the results of which can establish a reliable relationship between pathological rhythms of EEG and the dynamics of changes in cerebral blood flow - the amplitude of REG, arterioles tone and venous outflow. The achievement of the above technical result is illustrated by the following examples. At the initial manifestations of cerebrovascular insufficiency (NPNCM), EEGs with a high degree of synchronization (mainly in the alpha range) are often found. This is due to the activation of integrative structures of the mesencephalic level that occurs in response to a deterioration in the blood supply to the brain. With discirculatory disorders in the vertebrobasilar bed, phenomena of desynchronization and flattening of the EEG can be observed, with thrombosis and stenosis with the corresponding clinical manifestations (paresis, intermittent blindness and aphasia), changes in the EEG are manifested by slow waves of the delta and theta range. A close correlation was found between the volume of blood flow in the basin of the affected vessel and the average frequency of rhythmic activity in this area, which allows judging by the EEG data on the possibilities of compensation and rehabilitation for ischemic disorders of cerebral circulation. On the same basis, EEG is used to control brain functions during carotid endarterectomy operations.

In case of ischemic cerebrovascular accident, EEG data can, to a certain extent, serve differential diagnostic purposes. So, with carotid stenosis, pathological EEG occurs in 50% of patients, with carotid artery thrombosis - in 70%, and with sylvian artery thrombosis - in 95%. Electroencephalography in the differential diagnosis of vascular stroke is of particular importance. In hemorrhagic strokes, changes in the EEG are much more severe and persistent, accompanied by more pronounced cerebral changes, which corresponds to a more severe clinical picture. Synchronous registration of the listed electrophysiological signals makes it possible to identify the effect of the vascular factor in paroxysmal conditions and epilepsy by comparing changes in the parameters of cerebral blood flow preceding manifestations of epileptiform activity. For example, an inadequately strong deterioration in the parameters of cerebral blood flow (most often this is expressed in a decrease in pulse blood supply, an increase in vascular tone, an increase in instability of tone indicators, etc.) for ongoing functional tests can provoke the occurrence of epileptiform activity on the EEG. Comparing the degree of change in the parameters of cerebral blood flow by REG with the corresponding changes in the EEG, as well as the temporal relationships of these changes, a decision can be made on the predominant emphasis in the treatment of vascular disorders or on the joint use of drugs that improve cerebral hemodynamics and anticonvulsants. Simultaneous registration of the respiratory curve with the help of the respiratory belt helps to control the correctness of the tests with hyperventilation and breath holding. Such control is highly desirable for a correct meaningful interpretation, since superficial quickened or, on the contrary, slowed breathing during hyperventilation can lead to the opposite physiological effect (hypercapnia instead of hypocapnia).

If the moment of the appearance of epileptiform outbreaks and discharges is preceded by significant changes in the parameters of cerebral blood flow, this may indicate the primary effect of disturbances in the cerebral blood flow. For example, before a three-minute hyperventilation in the initial state, a somewhat disorganized alpha activity of high amplitude, irregular in frequency, was observed. The rheoencephalogram in the initial state was relatively normal in shape with a slightly increased tone. In the third minute of hyperventilation, outbreaks of polymorphic, mainly slow-wave (theta range and partially delta), epileptiform activity began to appear. Before the outbreak of REG, there is a significant instability of pulse blood supply and vascular tone of various calibers, even in neighboring cardiac cycles the amplitude of REG pulsations differs by one and a half or more times, the shape of the re-wave varies from hypotonic to hypertonic. Some changes are also observed in peripheral photoplethysmogram (PPG), in particular, an increase in the tone of resistive vessels (a decrease in the amplitude of the PPG pulsation).

Low values of the tone of cerebral arterioles correspond to minimal, in comparison with other groups of patients, changes in EEG. The growth of pathological elements of the EEG increases in proportion to the increase in the phenomena of intracranial hypertension. From a prognostic point of view, low initial values of tonus indices are evidence of the preservation of the central mechanisms of vasomotor regulation, and high values of tonus correlate with the loss of central mechanisms of vasomotor regulation and the initial manifestations of coronary artery disease.

As an illustration, consider a few research examples.

Example 1. In the first study (6 and 8), the patient showed a decrease in the threshold of convulsive readiness for hyperventilation. In the second study (Fig.7 and 9), the patient recorded a normalization of the EEG and REG values for hyperventilation.

The images in Figs. 7 and 8 illustrate the dynamics of trends in the initial state and when conducting a provoking 3-minute hyperventilation test for the following physiological parameters: heart rate (HR), amplitude of the systolic wave of PPG (ASV FPG), pulse wave propagation time (VRPV, FIG), the left occipital lead EEG index, the ratio of the power of the slow-wave components of the EEG (the sum of the subdialazones of the delta and theta waves) to the alpha power of the left frontal EEG lead (D + T / A, F3-A1), rheographic index on the left fronto-mastoidalnomu retracted REG (RI, FM_L), the constant component (AGR) in the left frontal EEG leads (SS, F3-A1).

In Fig.7, the following characteristic moments are noticeable. A provoking hyperventilation test leads to combined changes in almost all physiological signals, in particular, a sharp increase in heart rate (from 84 to 106 beats / min), a sharp increase in the tone of peripheral resistive vessels (ASV PPG in the background was about 4 pm, and reached 0 in HB) , 47 pm, i.e., the amplitude of the pulsation of resistive vessels decreased several times), a significant decrease in the alpha index at the 3rd minute of hyperventilation (in the background about 70%, at the 3rd minute - about 20%), a sharp increase in the prevalence pathological slow-wave components (delta and theta) over normal alpha activity - more than 10 times, a sharp decrease in pulse blood supply by REG-RI decreased from 1.2-1.35 to 0.7-0.8 Ohms, an increase in the level of constant potential in the process of hyperventilation (almost 2 mV). The completion of the provocative test led to the gradual normalization of most physiological parameters: heart rate decreased almost to the initial values (87 beats / min). VRPV increased even above the initial values, which indicates a significant decrease in the tone of the main arteries. The alpha index of the occipital leads of the EEG has recovered. The ratio of slow-wave and fast-wave components of the EEG normalized.

Figure 6 presents the physiological signals (EEG, REG, ECG, PPG). On the left is the initial background state, on the right is the 3rd minute of hyperventilation. A marked deterioration of the EEG and REG signals on the provoking effect, in particular, a decrease in the pulse blood supply to the cerebral vessels (RI REG) and the appearance of paroxysmal flashes of slow-wave activity on the EEG.

Example 2. On Fig and 9 shows a comparative diagram of the dynamics of the average EEG, REG, ECG, PPG on provocative effects in the second study, when the patient was fixed normalization of EEG and REG on hyperventilation. The initial state is characterized by a low-amplitude desynchronized EEG (alpha waves are almost not noticeable), increased tone of the cerebral vessels (the second systolic wave is higher in amplitude than the first, PPSS 100%), decreased pulse blood filling (RI at the level of 0.08 ... 0, 09 ohms). With the provoking effect in the form of hyperventilation, the following changes are observed: the alpha rhythm is much more pronounced with normal zonal differences preserved, the tone of the cerebral vessels normalized (the second systolic wave became lower than the first in amplitude, PPSS at 70%), the pulse blood supply to the cerebral vessels returned to normal (RI at the level of 0.12 ohms).

Comparison of deviations of physiological parameters in two patients allows us to draw the following conclusions. In the 1st patient with a revealed increase in the seizure threshold for hyperventilation, it should be noted that a deterioration in EEG indicators (a 40% decrease in alpha activity, an increase in the ratio of slow-wave delta and theta activity to alpha by 4.7 times) is accompanied by a decrease in performance pulse blood filling of cerebral vessels (reduction of the rheographic index by 30%). First, there is a significant deterioration in cerebral blood flow (observed from the 1st minute of hyperventilation), and then the occurrence of paroxysmal manifestations of pathological activity (at the 3rd minute of hyperventilation). With hyperventilation, the amplitude of pulsations of peripheral PPG decreases (by 46%).

For a patient with normalization of EEG indices during hyperventilation, a different picture is observed. The hyperventilation test leads to normalization of the EEG (an increase in the alpha index by 64%, a decrease in the ratio of slow-wave delta and theta activity to alpha by 35%) is accompanied by an improvement in the pulse blood filling of the cerebral vessels (an increase in the rheographic index by almost 30%). Normalization of EEG and REG begins simultaneously 30 seconds after the start of hyperventilation. The hyperventilation test leads to a significantly larger increase in the tone of the peripheral vessels (a decrease in the amplitude of pulsations of the finger PPG by 5.5 times, whereas in the first patient, the decrease in PPG was only 2 times).

It can be assumed that the second patient in the initial state had insufficient oxygen content in the blood, due to which the initial EEG and REG values were somewhat disturbed. Hyperventilation led to an increase in the oxygen content in the blood, which led to the normalization of cerebral blood flow and EEG. In addition, the second patient seems to have more developed adaptive capabilities, as with a provocative effect, adaptation mechanisms worked to increase the tone of the peripheral vessels, which means that the ratio for the redistribution of total blood flow in favor of the cerebral due to peripheral has improved. In the first patient, the peripheral vascular tone increased slightly, the corresponding redistribution of blood flow did not occur, cerebral blood flow decreased significantly, which could lead to a deterioration in EEG.

It should be noted that sharp changes in the indicators of EEG, REG, CMA are observed in many cases and when performing mental stress. Figure 10 shows the trends in physiological indicators for EEG, REG, ECG, SMA - the constant component of the electrocardiogram (PS EEG) during arithmetic and linguistic tests. Sharp changes in the alpha index and PS EEG are noticeable. After mental exertion, there is a compensatory increase in RI REG. The method of combined analysis of EEG, REG and SMA can also be successfully used to conduct research in various groups of patients with mental and neuropsychiatric abnormalities to study memory mechanisms, etc.

A device for studying the functional state of the brain, using which the claimed method is implemented, contains (Fig. 1) a block of electrodes 1 for collecting signals of bioelectrical activity of the brain, a block of 2 sensors of electrophysiological signals, a block of 3 current and potential electrodes for recording re-signals, a lead switch 4, a generator of 5 current re-signals, a synchronous detector of 6 re-signals, a multi-channel amplifier 7 signals of bioelectric activity of the brain, an amplifier of 8 electrophys iologicheskih signals, the demultiplexer 9, reosignalov multichannel amplifier 10, multichannel analog-to-digital converter (Matzpen) 11, a microcomputer 12 with electrically isolated input-output port, dual frequency precision current generator 13 and the PC 14, a standard configuration. Block 1, which includes a device for fixing electrodes, working (signal), reference and zero electrodes, connecting conductors and a connector for connecting to a multi-channel amplifier 7, can be made in the form of an elastic cap and is intended for convenient and comfortable fixing of electrodes on the patient's head. Block 2 includes at least electrocardiographic electrodes and photoplethysmographic sensors and oculograms and elements for fixing electrodes and sensors on the patient’s body. If it is necessary to control the duration and depth of breathing during a functional test for hyperventilation, block 2 may additionally contain a respiratory wave sensor (for example, a respiratory belt). Block 3 includes current electrodes for supplying current pulse signals and potential electrodes for removing the voltage drop from current pulse signals and can be combined with block 1, i.e. current and potential electrodes can be fixed on the same elastic cap, while in the fastening elements the electrodes of block 3 are grouped in pairs - current electrode b 1 and the corresponding potential electrode B 1 . Switch 4 is designed for temporary separation of rheosignals and includes two demultiplexers, one of which connects the current electrodes of block 3 to the output of the generator 5 and the potential electrodes of block 3 with even numbers to the input of the synchronous detector 6, and the other with odd numbers. The generator 5 (Fig. 3) contains a constant voltage source E, the poles of which are controlled by a switch 15, a narrow-band amplifier including C3, R7, Y3, and a low-pass filter 16 are connected to the input of the voltage-current linear converter (U4, Tp1, R8) . At the output of the generator 6, the frequency of the sinusoidal current is equal to the switching frequency of the controlled switch 15. The synchronous detector 6 (Fig. 4) contains a differential amplifier U5 with a bandpass filter 17 at the output and a controlled switch 18, one input of which is connected directly to the bandpass filter, and the second through an inverter . The control inputs of the switches 15 and 18 are fed synchronous signals from the microcomputer 12. The multi-channel amplifier 7 is designed to amplify the signals of the bioelectric activity of the brain, recorded using the working electrodes of unit 1. Each amplification channel of this amplifier contains (Fig.2) a series-connected differential amplifier (U1 , R1, R2), an amplifier with a constant current coefficient equal to unity, and gain in the working frequency band (У2, R3, R4, R5, С1), and a low-pass filter. The non-inverting input of the differential amplifier is connected to the corresponding working electrode of block 1 and one of the outputs of the two-frequency precision generator 13, and the inverting through the matching stage with the corresponding reference electrode A. The two-frequency precision current generator 13 with synchronization from the microcomputer 12 can be implemented in the form of two reference frequency dividers with different division factors (figure 5). The frequency f 1 at the output of the frequency divider 19 is more than 1.5 ... 2.0 times the upper f vex frequency of the analyzed signals, the frequency f 2 at the output of the frequency divider 20 is greater than the frequency f 1 , for example, if the upper frequency of the analyzed electroencephalographic signals is 300 Hz , then the frequency at the output of the frequency divider 19 is set within 450 ... 500 Hz. The frequency of the frequency divider 20 is set different from the frequency of the frequency divider 19 to 50 ... 100 Hz. By narrow-band filtering by digital methods, the signals of these generators are extracted from the output voltages of the multi-channel amplifier 7 and are used in the calculation of sub-electrode resistances. The current generator mode is ensured by the fact that the output of the divider is connected to each electrode of block 1 through a high-Q capacitor of small capacity (10 ... 20 pF). The output of the frequency divider 19 is connected to the working electrodes of block 1, the output of the frequency divider 20 is connected to the reference electrodes. The amplifier 8 contains an amplifier stage for each of the electrophysiological signals. The electrical circuits of these cascades are made without any features, their description is given in textbooks. The output of the synchronous detector 6 is connected to the input of the multiplexer 9, the outputs of which are connected to the inputs of the multi-channel amplifier 10. The outputs of the multiplexer 9 are connected from the microcomputer 12 synchronously with the switching of the electrodes of block 3 by the lead switch 4. The outputs of the multi-channel amplifiers 7 and 10 and the amplifier 8 are connected to the corresponding inputs multi-channel analog-to-digital Converter 11, the purpose of which is the conversion of analog signals into discrete form with spatial separation of channels. The microcomputer is designed to provide real-time removal of all signals, their preliminary processing (digital filtering), monitoring the operation of unit 1 and multi-channel amplifier 7 and controlling the operation of switch 4, generator 5, synchronous detector 6, multiplexer 9, two-frequency precision generator 13 and multichannel analog-to-digital Converter 11. Microcomputer 12 channel is connected to the PC 14. The purpose of the PC 14 is the statistical processing of recorded synchronously in real time electrophysiological signals (EEG, ECG, REG, SMA, PPG), calculation in a single cardiocyclic time scale, i.e. in relation to each of the automatically recognized cardiocycles, physiological indicators: bioelectrical activity of the brain - absolute and relative values of the power of alpha activity, pathological slow-wave activity in the range of delta and theta waves, the dynamics of the level of brain metabolic activity in the constant component of EEG, ECG heart rate, pulse blood vessels in the brain vessels according to the rheographic indexes of REG, peripheral resistance of the cerebral vessels (PPSS), ne tone peripheral in the form of the amplitude of the pulsation of the peripheral PPG, the tone of the main vessels according to the propagation time of the pulse wave from the Q wave of the ECG signal to the beginning of the systolic wave of the peripheral PPG, the tone of the post-capillary-venular vessels by the constant component of the PPG, the display of these indicators on the display screen in volume and in the form for differential diagnosis of epilepsy and epileptiform manifestations.

The claimed device operates as follows. Electrodes for taking an electroencephalogram and rheogram are fixed on the head using an elastic helmet (a special electrode elastic cap), electrodes for taking an electrocardiogram and sensors for skin-galvanic reaction, pulsometry (PPG) and myography are fixed to the patient using electrically conductive glue or adhesive tape, a respiratory wave - using the respiratory belt. During long-term monitoring, when the exchange channel between the microcomputer 12 and the PC 14 is organized via a radio channel, accelerometers can additionally be fixed on the patient, the signals from which establish the patient’s motor activity. The communication of the PC 14 with the microcomputer 12 via the radio channel not only allows the patient to be in comfortable conditions, but also monitor several patients at the same time. After installing the electrodes and sensors of the unit 1 ... 3 and turning on the power, the operability and reliability of connecting the electrodes and sensors is checked. Subelectrode resistances are measured, and if the subelectrode resistance of an electrode exceeds a threshold value, then its serviceability and reliability of the installation are checked, a faulty electrode is replaced, a working one is reinstalled. Then turns on the microcomputer 12 in the mode of picking up physiological signals. The electrical signals supplied to the inputs are amplified, converted into an MAPC 3 from an analog form to a discrete one, cleared of artifacts in a microcomputer 4 and stored in code form in the drive 10. The speed of the microcomputer 4 and the capacity of the drive 10 allow real-time synchronous recording and storage daily monitoring data: EEG signals for the required number of leads (up to 32 digital leads); rheographic signals (up to 6 channels); physiological signals along the channels: ECG, EOG, PG, EMG; body position signals from gyroscopic sensors; values of subelectrode resistances; markers of various types; reflecting certain events; functional tests, scheduled by the program or conducted by a doctor in the process of EEG-video monitoring; pretreatment results to identify EEG and ECG abnormalities. The recorded information from the microcomputer 12 is transmitted to the PC 14 connecting it to the port of the PC 14, or over the air. In PC 14, the necessary fragments of electrophysiological signals are processed and, depending on the purpose of the study, the processes that are necessary for the doctor to visually evaluate the processes are displayed in a single time interval.

Processing is performed using all the possibilities of mathematical processing. For example, the processing of an electroencephalogram is performed using all the capabilities of a computer-based electroencephalograph, such as reference reconstruction, vertical “split”, automatic search for artifacts and epileptiform activity, two- and three-dimensional toposcope, spectral, auto-correlation analysis and coherence function with topographic mapping, analysis of functional asymmetries, as well as automatic generation of descriptions and classification of EEG with the ability to edit, three-dimensional okalizatsiya pathological sources of brain electrical activity, etc.

Long-term monitoring of the electroencephalogram and other physiological parameters simultaneously removed from it is an important diagnostic method that allows us to differentiate between pseudoepileptic and true epileptic paroxysms. EEG video monitoring is used when it is necessary to confirm the correctness of the preliminary diagnosis of “epilepsy”, especially in complex cases where accurate differential diagnosis is crucial for choosing the best treatment tactics and predicting the course of the disease. The diagnosis of epilepsy is evident when epileptic EEG patterns are detected on the interictal / paroxysmal EEG. The absence of EEG abnormalities in the interictal / attack period does not completely exclude epilepsy. It is known that a significant number of simple partial paroxysms, accompanied by vegetative or somatosensory symptoms, are often characterized by the absence of changes in the EEG during superficial application of electrodes. The presence of epileptic EEG patterns at the time of the attack is also not absolute evidence of epilepsy. Patients with rhythmic repetitive motor phenomena on the EEG in some cases have artifacts resembling epileptic EEG patterns and capable of misleading an inexperienced electroencephalographist. To avoid errors, it is necessary to compare synchronous changes in EEG and REG studies. When preparing a patient, it is advisable to use a combined electrode system containing EEG and REG channels.

To obtain complex information during the examination of a particular patient, simultaneous aggregate registration of the brain's electrical activity and parameters of cerebral circulation is used. Such an approach not only saves research time due to a single recording in the initial (background) state and during functional tests as part of a simultaneous EEG-REG study. Obtaining complex information when comparing the dynamics of synchronous changes in EEG, REG and ECG during the simultaneous study, which in turn allows you to:

- evaluate the possible effect of the vascular factor on paroxysmal manifestations (if any);

- identify possible cerebrovascular causes of changes in the bioelectric activity of the brain;

- to compare paroxysmal manifestations on the EEG and signs of heart rhythm disturbance and ECG conduction (if any) in order to identify the type of disorders (cardiogenic or cerebrogenic);

- to analyze the interaction of the central nervous system, the ANS and cerebral circulation based on a comparison of the dynamics of the EEG, REG and ECG signals, as well as physiological parameters calculated on the basis of these signals.

According to the data obtained using the claimed device, patients with initially low levels of cerebral blood flow are characterized by a significant increase in the number of diffuse pathological theta inclusions equivalent to the processes of demyelination, atherosclerosis, and diffuse brain ischemia. In patients with excessive plethora of cerebral vessels (RI = 0.3 Ohm), moderately reduced tone and slowed venous outflow, signs of bilaterally synchronized rhythm are also observed, reflecting the phenomena of dysfunction of the median brain formations. That is, in both cases, significant deviations of the hemodynamic components of the brain indicate a violation of the central mechanisms of regulation of vasomotor control. Slowing of the venous outflow, specific for the phenomena of increased blood supply to the brain and high tone of the arterioles, indicates an increase in intracranial hypertension with a loss of negative feedback between the center and the main components of the cerebral blood flow, which correlates with EEG manifestations of irritative and diffuse changes in the functional state of the brain stem. Low values of arteriole tone corresponded to minimal, in comparison with other groups of patients, changes in EEG. The growth of pathological elements of the EEG increased in proportion to the increase in the phenomena of intracranial hypertension. From a prognostic point of view, low initial values of tonus indices are evidence of the preservation of the central mechanisms of vasomotor regulation, and high values of tonus correlate with the loss of central mechanisms of vasomotor regulation and the initial manifestations of coronary artery disease.

Comparison of EEG and REG from the point of view of identifying the provoking factors of elements of epileptiform activity is important. If the moment of the appearance of epileptiform outbreaks and discharges is preceded by significant changes in the parameters of cerebral blood flow, this may indicate the primary effect of disturbances in the cerebral blood flow.

However, this does not limit the possible scope of synchronous recording of EEG and printing signals that reflect the activity of cerebral, central and peripheral blood flow. Given the dependence of the functional state of the brain on the state of the cardiovascular system, taking into account changes in the recorded parameters of the vascular system can help in interpreting the emerging phenomena on the EEG. This may apply to the identification of the triggering factors of epileptic seizures (analysis of changes in cerebral blood flow that preceded the onset of the attack), and for the differential diagnosis of epileptic and non-epileptic seizures (for example, incidence of syncope states associated with cardiac arrhythmias or vasodepressor reactions), to the identification of EEG disturbances cerebrovascular nature (upon the normalization of EEG and REG when conducting any tests, such as hyperventilation), and to confirm the presence of p gulyatornyh disorders manifested in the EEG, REG and heart rate variability. In the framework of separately conducted studies of EEG, REG, cardiointervalography, and indicators of central hemodynamics, the same functional tests are often used. Synchronous registration of these data allows not only to reduce the total study time, but also to get a unique opportunity to compare indicators obtained from different types of signals in order to more reliable interpretation of the data. A comparison of these data allows us to clarify the nature of the underlying vascular disease and the regionality of cerebrovascular disorders. In addition to REG and ECG, it is advisable to use other physiological signals. These may include peripheral photoplethysmogram (PPG, to control the reactivity of resistive vessels, the tone of the main arteries, the state of the post-capillary-venous bed), galvanic skin reaction (RAG, to control psychoemotional stress, especially during psychological tests), pneumogram (PG, for assessment of the frequency and depth of breathing, control of the correctness of various respiratory tests) and other signals.

Analysis of super slow brain activity is practically the only electrophysiological method that allows us to estimate the magnitude of cerebral energy consumption. Metabolic disorders play an important role in the development of vascular and atrophic diseases of the brain, epilepsy and affect the course of neurotic disorders. Registration of SMA with the necessary accuracy is ensured only with the measurement of sub-electrode resistances and taking into account their changes during monitoring.

The method of measuring the electrode resistance is illustrated by the circuit depicted in figure 10. Figure 10 shows: 1e, 2e - electrodes connected to the inputs of a differential amplifier, 1 ... k - working electrodes, a - reference electrodes, Jf 1 - current generator with frequency f 1 , Jf 2 - current generator with frequency f 2 , Zd1, Zd2, Za, Z1 ... Zk are the electrode resistance of the electrodes 1d, 2d, a, 1 ... k, respectively, Ud, Ya, Y1 ... Yk are the differential, reference, and working amplifiers, respectively, f 1 , f 2 - band-pass filters, U f1 , u f2 - voltage at the output of amplifiers Ud, Wa, U1 ... UK.

The claimed method of measuring the sub-electrode resistance during registration using input amplifiers of the brain biopotentials and / or electrical signals generated by the heart and / or electrical signals of muscle movements is implemented as follows. A signal from a narrow-band current generator Jf 1 with a frequency f 1 exceeding the upper frequency of the recorded signals f Вepx is supplied to each working electrode, and a signal from a narrow-band current generator Jf 2 with a frequency f 2 is supplied to the reference electrode

Figure 00000002
f 1 > f vepx . By narrow-band filtering, the voltage with a frequency of f 1 -U f1 and the voltage with a frequency of f 2 - U f2 are isolated from the output voltage of each working amplifier U1 ... Uk, the electrode resistance of the working electrode is determined by the formula Z j = U jf1 : (J 1 × K j ), where Z j is the sub-electrode resistance of the j-th working electrode, U jf1 is the voltage at the output of the j-th working amplifier with a frequency f 1 , Jf 1 is the current of a narrow-band current generator with a frequency f 1 , K j is the gain j-th working amplifier, the sub-electrode resistance of the reference electrode is determined according to the formula Za = U jf2 : (J f2 × K j ), where Za is the sub-electrode resistance of the reference electrode associated with the j-th working amplifier, U jf2 is the voltage at the output of the j-th working amplifier with frequency f 2 , J f2 is the current narrowband current generator with a frequency of f 2 . The amplification factors of the amplifiers are measured before installing the electrodes, for example, as the ratio of the voltage at the output of the amplifier to the calibrated voltage at the input. The current generators Jf 1 and Jf 2 can also be pre-calibrated. The frequencies f 1 and f 2 are selected from the condition of excluding the influence on the measurement results of the analyzed signals. Since the change in the subelectrode resistances is influenced by slow processes, the operation of the generators Jf 1 and Jf 2 can be separated in time. Then there is no need to combat combinational frequencies.

Claims (15)

1. A method for studying the functional state of the brain, including multi-channel recording of an electroencephalogram (EEG), electrocardiogram (ECG) and conducting a functional test, characterized in that it additionally with multi-channel recording of EEG and computer spectral analysis of artifacts lacking EEG fragments with an estimate of the power of spectrograms in standard frequency the ranges synchronously and in real time, they record the ultra slow brain activity, record the rheoencephalogram (REG) in the pools with nnyh and vertebral arteries photoplethysmogram (PPG), fingers and / or toes and the measurement of resistances of electrodes subelectrode pickup signals bioelectric activity of the brain, with a single pokardiotsiklovom time scale, i.e. in relation to each of the automatically recognized cardiocycles, physiological indicators of the brain bioelectrical activity are calculated and visualized - the absolute and relative values of the alpha activity power, pathological slow-wave activity in the range of delta and theta waves, the level of constant potential for super slow brain activity, frequency ECG heart rate, pulse blood vessels of the brain vessels by Rheographic indexes REG, the indicator of peripheral resistance I of cerebral vessels (PPSS), an indicator of peripheral tonus in the form of an amplitude of pulsation of peripheral PPG, an indicator of the tone of the main vessels according to the time of propagation of a pulse wave from the Q wave of the ECG signal to the onset of a systolic wave of peripheral PPG, an indicator of the tone of post-capillary-venous vessels by the constant component of the PPG, and the functional state of the brain is determined by the dynamics of changes in physiological parameters before, during and after a functional test.
2. The method according to claim 1, characterized in that they carry out a functional hyperventilation test and if, after the start of the test, a decrease of more than 20% in the rheographic index of the REG is observed, and then paroxysmal manifestations on the EEG are observed in the form of a sharp increase in the ratio of pathological slow-wave waves to delta and theta ranges for alpha activity, then a potential cause of paroxysmal manifestations on the EEG formulate vascular disorders of the brain.
3. The method according to claim 2, characterized in that if the decrease in the rheographic index of REG and the appearance of paroxysmal manifestations on the EEG is accompanied by a shift in the level of the constant potential of super slow brain activity, it is concluded that there is an effect of the vascular factor on paroxysmal manifestations, accompanied by metabolic changes.
4. The method according to claim 2, characterized in that if the decrease in the rheographic index of REG and the appearance of paroxysmal manifestations on the EEG is not accompanied by a significant decrease in peripheral blood flow by PPG, then a potential regulation of vascular disorders of the brain is formulated by the insufficiency of regulatory processes for compensatory decrease in peripheral blood flow and the redistribution of total blood flow to vital organs.
5. The method according to claim 2, characterized in that if the localization of the decrease in the rheographic index of REG and the appearance of paroxysmal manifestations on the EEG coincides, then it is additionally concluded that there is a focus of pathological activity that determines the inadequacy of regional cerebral blood flow.
6. The method according to claim 1, characterized in that they carry out a functional hyperventilation test and if EEG disorganization, decreased pulse blood supply and increased tone by REG were observed prior to the functional test, and normalization of cerebral blood flow was observed during the test, which is expressed in an increase pulse blood supply, a decrease in the index of peripheral resistance of cerebral vessels and normalization of EEG, expressed in an increase in the level of alpha activity while maintaining zonal differences about fronto-occipital regions, a decrease in the ratio of pathological slow-wave waves in the delta and theta ranges to alpha activity, then they formulate the assumption of the presence of cerebrovascular disorders associated with a violation of the gas composition of the blood in the initial background state.
7. The method according to claim 1, characterized in that a functional test for hyperventilation is carried out and if during the test the extrasystoles are observed on the ECG signal and they are preceded by paroxysms on synchronously recorded EEG signals, then a conclusion is drawn about the cerebrogenic nature of heart rhythm disturbances.
8. The method according to claim 1, characterized in that a long passive orthostatic test is carried out, and if the patient has a syncopal state during the test, then with pronounced bradycardia or asystole on the ECG until the onset of the synocopal state and a decrease in cerebral blood flow is diagnosed by REG cardioinhibitory cause of syncope, with previous signs of deposition of blood in the extremities preceding the synocopal state by PPG and a decrease in cerebral blood flow by REG and the absence of a significant decrease in heart rate by ECG, a vasodepressive cause of the syncopal state is diagnosed, and with previous paroxysms of the syncopal state on the EEG and the absence of a significant decrease in heart rate by ECG and pronounced signs of blood deposition in the extremities, the convulsive type of syncope is diagnosed.
9. A device for studying the functional state of the brain, containing a series-connected multichannel analog-to-digital converter, a microcomputer with galvanically isolated input-output ports and a PC of a standard configuration, an electrode block for picking up signals of the bioelectrical activity of the brain, connected to a multi-channel amplifier of signals of the bioelectric activity of the brain brain, an electrophysiological signal sensor unit connected to an electrophysiological signal amplifier s, a block of current and potential electrodes for recording reosignals, a multi-channel amplifier of reosignals, a generator of current reosignals and a synchronous detector of reosignals, additionally contains a two-frequency precision current generator whose input is connected to a microcomputer, the first group of outputs is connected to working electrodes, and the second to reference electrodes of the block of electrodes for picking up signals of bioelectrical activity of the brain, lead switch, the first group of inputs of which is connected to potential electrodes of the current and potential electrodes block for recording re-signals, the second group of inputs - with the outputs of the current re-signal generator, the first group of outputs - with current electrodes of the current and potential electrode blocks for recording the re-signals, the second group of outputs - with inputs of the synchronous re-signal detector, demultiplexer the input of which is connected to the output of the synchronous rheosignal detector, and the outputs are connected to the inputs of the multichannel rheosignal amplifier, the outputs of the multichannel amplifier an amplifier of signals of bioelectric activity of the brain, a multi-channel amplifier of rheosignals and an amplifier of electrophysiological signals are connected to the corresponding inputs of the multi-channel analog-to-digital converter, the outputs of the microcomputer are connected to the control input of the lead switch, the control input of the demultiplexer, the control input of the multi-channel analog-to-digital converter and synchronization inputs of the current rheosignal generator and a synchronous rheosignal detector.
10. The device according to claim 9, characterized in that the block of electrophysiological signal sensors contains electrodes for sensing electrical activity of the heart, electrical signals of muscle motor activity, a pulse wave photosensor and a respiratory wave sensor.
11. The device according to claim 10, characterized in that the generator of current rheosignals contains a constant voltage source, the poles of which are connected to the switched inputs of the controlled switch, the output of the controlled switch through a narrow-band voltage amplifier connected to the input of the linear voltage-current converter, the output of which is the output of the generator .
12. The device according to claim 10, characterized in that the synchronous rheosignal detector comprises a differential amplifier, a bandpass filter and an inverter connected in series, as well as a controllable switch, the switched inputs of which are connected to the input and output of the inverter, the inputs of the differential amplifier and the control are inputs controlled switch input, output - controlled switch output.
13. The device according to claim 10, characterized in that the two-frequency precision current generator contains two frequency dividers, the inputs of which are combined and are the driving input of the generator, and the outputs through capacitors with a capacity of 10 ... 20 pF are respectively connected to the working electrodes and reference electrodes.
14. The device according to claim 10, characterized in that the amplification channel of the multichannel amplifier of signals of bioelectric activity of the brain contains a differential amplifier connected in series, the non-inverting input of which is connected to the input for connecting the corresponding working electrode, and the inverting channel through the matching cascade with the input for connecting the reference an electrode, an amplifier with a DC gain of unity, and a gain in the working frequency band equal to the nominal, and a filter p low frequencies.
15. The method of measuring the sub-electrode resistance during registration using differential amplifiers of the biopotentials of the brain, characterized in that for each working electrode a signal is supplied from a narrow-band current generator with a frequency f 1 exceeding the upper frequency of the recorded signals f vepx , and a signal from narrow-band current generator with a frequency of f 2 ≠ f 1 > f Вepx , narrow-band filtering is isolated and measured at the output of each voltage amplifier with frequencies f 1 and f 2 - U f1 and U f2 , while the electrode resistance of each working electrode is determined by the formula Z j = U jf1 : (J f1 × K j ), where Z j is the sub-electrode resistance of the j-th electrode, U jf1 is the voltage at the output of the j-th amplifier with a frequency f 1 , J f1 is the current of a narrow-band current generator with a frequency f 1 , K j is the gain of the j-th amplifier, and the electrode resistance of the reference electrode is determined by the formula Z A = U jf2 : (J f2 × K j ), where Z A is the electrode resistance of the reference electrode a communion j-th amplifier, U jf2 - voltage at the j-th output of the amplifier with a frequency f 2, J f2 - current uzkopol waist current generator with a frequency f 2.
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