Changes in EEG Rhythms and Spike Activity of Brainstem Dopaminergic Neurons Induced by Neurofeedback Sessions in Cats

We examined the dynamics of the ratios of spectral power densities (SPDs) of the alpha vs theta rhythms (α/θ ratio). of EEG and of the spiking frequency of supposedly dopaminergic (DA) neurons of the ventral tegmentum in the course of neurofeedback sessions directed toward changes in the EEG characteristics. Trainings were performed using techniques analogous to that used in neurofeedback sessions in humans. The level of the noise acoustic signal presented to the animal decreased with increase in the α/θ ratio in the occipital leads. In the control realizations, there were no dependences between the intensity of the acoustic signal and modulation of the current EEG. It was found that the animals learned, in a conditioned-reflex mode, to correlate changes in the intensity of the sound signal and power of the EEG rhythms and to control the latter; a high sound intensity was probably considered a factor of discomfort. The α/θ ratio in the course of neurofeedback sessions changed due to some increase in the SPD of the alpha EEG component and a noticeable drop in the SPD of theta oscillations. In a parallel manner with such modifications, augmentation of the spike activity of DA neurons was observed. Probable mechanisms of the involvement of the cerebral DA system in the formation of the effects of neurofeedback sessions are discussed.     

Dynamics of EEG potentials at the beginning of a series of EEG-feedback sessions

We studied changes in the amplitudes of event-related EEG potentials (ERPs) and power spectra of background EEG in the course of a series of EEG-feedback sessions directed toward an increase in the ratio of powers of the α vs θ rhythms. The examined group included 70 volunteers divided into an experimental group (n = 37) and a control group (n = 33). The intensity of acoustic white noise overlapping the musical background served as a feedback signal; it became lower with increase in the above ratio, while in the control group it remained constant. The EEG potentials were recorded from C3 and C4 leads. The ERPs were recorded within a paradigm of measuring time intervals. Within a series of EEG-feedback sessions, the α/θ ratio decreased somewhat both in the control and experimental groups, but in subjects of the latter group this decrease was less significant, and the mean intragroup index became significantly greater than the respective value in the control group after the end of the third session. The EEG-feedback sessions also resulted in significant increases in the amplitudes of early components of the readiness potential in both hemispheres and in the amplitude of the contingent negative variation in the right hemisphere. We conclude that, in most healthy subjects, at least three sessions of α/θ training are necessary to form an effective series providing considerable changes in the pattern of EEG potentials. Neirofiziologiya/Neurophysiology, Vol. 39, No. 1, pp. 88–98, January–February, 2007.     

Correlation of the characteristics of EEG potentials with the indices of attention in 12-to 13-year-old children

We studied correlations of the spectral characteristics of EEG with the indices characterizing the level of attention in 60 children (12 to 13 years old). Indices of voluntary attention were measured using a complex of psychological tests, including a Bourdon’s test (correcture test), a two-stimulus go/no-go test, a computer test (a modification of the Bourdon’s test for characterization of concentration and stability of attention), and Schulte’s tables. Children manifesting a good working ability (corresponding to the results of the go/no-go test and correcture test) showed relatively high values of the ratio of spectral powers (SPs) of the beta 1 and theta rhythms. These ratios were greater in the right hemisphere; this is probably indicative of a greater contribution of neuronal mechanisms of this hemisphere to providing watchfulness and stability of attention. Children demonstrating increased impulsivity (according to the results of the go/no-go test) were characterized by low modal frequencies of the alpha rhythm in the occipital brain regions, while children with relatively high values of this frequency in various cerebral regions demonstrated high indices of attentiveness and rates of the cognitive processes. Children performing the test task with especially high accuracy were characterized by high ratios of SPs of the low-frequency beta rhythm vs theta rhythm (mostly in the central and parietal regions of both hemispheres). The approach we have applied can be used for measuring the objective indices characterizing the state of the attention sphere in children. Neirofiziologiya/Neurophysiology, Vol. 38, No. 3, pp. 248–256, May–June, 2006.     

Moderation of Increased Anxiety in Children and Teenagers with the Use of Neurotherapy: Estimation of the Efficacy

We estimated the efficacy of using the technique of feedback (FB) by EEG characteristics (EEG-FB, neurotherapy) with the aim of reducing increased anxiety levels in healthy 10- to 14-year-old children. The anxiety level was estimated using the Prikhojan anxiety test, the Spielberger–Khanin questionnaire, and the House–Tree–Person projective drawing technique. Positive effects of series of neurotherapy sessions were obvious. After training was completed, we observed significant increases in the ratios of the amplitudes of alpha and theta rhythms, semsorimotor and theta rhythms, as well as of the modal frequency of the EEG alpha rhythm in tested persons of the experimental group (n = 7). In the control group (n = 10), changes in these values did not reach the significance level. In the experimental group of tested persons subjected to EEG-FB sessions, the anxiety level decreased appreciably; in addition, the indices “feeling of inferiority” and “frustration” decreased significantly. In the control group, alterations of these psychological indices were not unidirectional. Therefore, modifications of the EEG pattern, which occurred in the course of training and were accompanied by a decrease in the anxiety level in the experimental group, can be indicative of the expediency of EEG-FB for the reduction of high anxiety levels in children and teenagers.     

Correlations between the psychological peculiarities of an individual and the efficacy of a single neurofeedback session (by the EEG characteristics)

Modifications of different EEG rhythms induced by a single neurofeedback session (by the EEG characteristics) directed toward an increase in the ratio of the spectral powers (SPs) of the α vs θ oscillations were compared with the psychological characteristics of the tested subjects (the group included 30 persons). A generally accepted neurofeedback technique was used; the intensity of acoustic white noise served as the feedback signal. EEG potentials were recorded from the C3 and C4 leads. Psychological testing was carried out using Eysenck’s (EPQ), Rusalov’s (OST), and (16 PF) questionnaires. The directions of changes in the SPs of EEG frequency components were found to significantly correlate with some individuality-related peculiarities of the tested subjects. The SP of the δ rhythm correlated with the EPQ scale “neuroticism,” OST scale “social plasticity,” and 16 PF factors H (“parmia”), I (“premsia”), and Q₃ (“self-control of behavior”). The SP of the θ component demonstrated correlations with the OST scales “ergisity,” “plasticity,” and “social temp” and with 16 PF factors M (“autia”), Q₄ (“frustration”), and Q1 (“exvia”). The SP of the α rhythm correlated with 16 PF factors Q₃ (“self-control of behavior”), G (“strength of superEgo”), O (“hypothymia”), L (“protension”), and N (“shrewdness”). The SP of the β rhythm correlated with the OST scale “emotionality,” while that of the γ rhythm showed correlations with the 16 PF indices L (“protension”) and M (“autia”). Changes in the ratio of the α vs θ SPs correlated with the EPQ scale “neuroticism.” Thus, our data confirm the statement that a high individual variability of the results of a single (first in the series) neurofeedback session is to a great extent related to peculiarities of the individual psychological pattern of the subject. Neirofiziologiya/Neurophysiology, Vol. 38, No. 3, pp. 239–247, May–June, 2006.     

Modulation of EEG Rhythms and Changes in Spike Activity of Noradrenergic Neurons of the <Emphasis Type="Italic">Locus Coeruleus</Emphasis> Related to Feedback Sessions by EEG Characteristics

In chronic experiments on awake cats, we studied the dynamics of the spectral power density (SPD) of the α rhythm vs SPD of the θ rhythm ratio and also of the characteristics of impulse activity generated by supposedly noradrenergic (NA) neurons of the locus coeruleus in the course of feedback (FB) sessions by EEG characteristics (EEG-FB). Trainings were performed using a technique analogous to that in EEG-FB sessions for humans. The level of a sound noise signal presented to the animal decreased with increase in the α/θ SPD ratio in the occipital lead. Changes in the level of the sound signal did not depend on EEG modulation in the control series. The animals were trained to correlate changes in the loudness of the sound signal with the power of EEG rhythms and, in such a way, to control the latter. The α/θ SPD ratio in EEG-FB sessions changed mostly due to a significant increase in the α rhythm power. The frequency of the impulse activity of NA neurons increased in a parallel manner with such EEG modulation. Possible mechanisms of the involvement of the cerebral NA system in the formation of the effects of EEG-FB sessions are discussed.     

Modifications of the EEG frequency pattern in humans related to a single neurofeedback session

We studied changes in the frequency pattern of EEG related to a single session of biological feedback by the EEG characteristics (neurofeedback, NFB) directed toward an increase in the ratio of α/θ spectral powers (SPs) (an experimental group; 30 subjects) and to a session of the supposedly indifferent acoustic influence (listening to a musical background; 30 persons). A standard technique of EEG recording was used; the loudness of white noise overlapping the musical background served as an NFB signal. EEG was recorded from the C3 and C4 leads. Within the examined experimental group, an NFB session elicited a trend toward statistically insignificant decreases in the SPs of δ, α, and β rhythms and increases in the SPs of θ and γ EEG components. Listening to a supposedly neutral musical background by the control group, with no attempts at self-control of the SPs of EEG rhythms, was followed by rather clear unidirectional (partially significant) decreases in the SPs of θ, α, β, and γ components; the δ activity in the left hemisphere decreased, while in the right hemisphere it increased. In general, results of the single NFB session were characterized by a high interindividual variability, which can be related mostly to the specificities of psychophysiological characteristics of the personality of the tested subject. Neirofiziologiya/Neurophysiology, Vol. 37, Nos. 5/6, pp. 443–451, September–December, 2005.     

Modifications of EEG Related to Repeated Static Grasp Efforts Developed by the Hand in Humans

The characteristics of EEG recorded before, in the course, and after three sequential static grasp efforts developed by the right hand were analyzed in 14 healthy volunteers of both sexes, 19 to 56 years old. The grasps were 3 min long, and intervals between the sequential trials were 5 min long. The mean intensity was, as a rule, the greatest in the first trial and decreased, because of fatigue, in the second and third trials. In the course of the grasp effort, significant (P ≤ 0.05) or close to significant decreases in the spectral power were observed in all trials within the alpha2 subrange in some frontal, central, and central/temporal leads. This reaction of desynchronization of alpha2 oscillations probably reflects activation of the sensorimotor cortical zones. Within the above period, the power of alpha2 oscillations increased in the occipital leads. In a few leads of the frontal group, the powers of delta, theta1, theta2, and alpha1 oscillations increased significantly (P < 0.05) in the course of the first trial. Such reaction was not observed in the second and third trials, while the powers of delta and alpha1 ranges increased in the occipital sites (P < 0.05). The powers of delta and theta oscillations increased, as compared with the control values, after the second and third grasps. Such specific EEG modifications in sequential trials can be related to the actions of a novelty factor in the first trial and a fatigue factor in the subsequent trials. The coherence coefficient (CC) of alpha and beta oscillations for symmetric leads usually increased in the course of the grasp. This effect reached a significance level (P < 0.05) for alpha2 oscillations in central, posterotemporal, parietal, and occipital pairs. The CC for beta2 oscillations increased in both temporal lead pairs. A drop in the interhemisphere coherence was more typical of the delta and theta1 ranges. Therefore, changes in the CC values show that the structure of interhemisphere interaction undergoes modifications with the development of the grasp static efforts. Neirofiziologiya/Neurophysiology, Vol. 37, No. 4, pp. 362–371, July–August, 2005.     

Peculiarities of EEG in hard-of-hearing children of primary school age

Electroencephalographic examination of 7-to 9-year-old children with sensorineural deafness of degrees II and III included EEG recording in the resting state, in the course of reaction of activation (at opening of the eyes), under conditions of rhythmic photostimulation with frequencies of 4, 6, 9, and 12 sec⁻¹ and under those of the hyperventilation test. The results allow us to conclude that systems responsible for generation of EEG in hard-of-hearing children demonstrate some functionally immaturity. The following facts confirm the above conclusion. As compared with the norm, greater normalized spectral powers (SPs) of the delta and theta rhythms, a higher intensity of electrogenesis (integral power of oscillations) within all frequency ranges, and a smaller mean frequency of the dominant rhythm were typical of hard-of-hearing children. In these children, the reaction of activation in the majority of cases looked like incomplete suppression of the alpha rhythm. Upon rhythmic photostimulation, hard-of-hearing boys and girls demonstrated following of the rhythm at frequencies of 4 and 6 sec⁻¹ while children with normal hearing demonstrated that at 9 and 12 sec⁻¹ frequencies. The characteristics of EEG reactions under the conditions of the hyperventilation test reflected the immaturity of the fronto-thalamic controlling system, as well as certain dysfunction of lower brainstem regions in children with disorders of hearing. Neirofiziologiya/Neurophysiology, Vol. 40, No. 2, pp. 137–146, March–April, 2008.     

Topographic analysis of dimension estimates of EEG and filtered rhythms in epileptic patients with complex partial seizures

Nonlinear dynamic properties were analyzed on the EEG and filtered rhythms recorded from healthy subjects and epileptic patients with complex partial seizures. Estimates of correlation dimensions of control EEG, interictal EEG and ictal EEG were calculated. The values were demonstrated on topograms. The delta (0.5–4 Hz), theta (4–8 Hz), alpha (8–13 Hz), beta (13–30 Hz) and gamma (30–40 Hz) components were obtained and considered as signals from the cortex. Corresponding surrogate data was produced. Firstly, the influence of sampling parameters on the calculation was tested. The dimension estimates of the signals from the frontal, temporal, parietal and occipital regions were computed and compared with the results of surrogate data. In the control subjects, the estimates between the EEG and surrogate data did not differ (P > 0.05). The interictal EEG from the frontal region and occipital region, as well as its theta component from the frontal region, and temporal region, showed obviously low dimensions (P < 0.01). The ictal EEG exhibited significantly low-dimension estimates across the scalp. All filtered rhythms from the temporal region yielded lower results than those of the surrogate data (P < 0.01). The dimension estimates of the EEG and filtered components markedly changed when the neurological state varied. For each neurological state, the dimension estimates were not uniform among the EEG and frequency components. The signal with a different frequency range and in a different neurological state showed a different dimension estimate. Furthermore, the theta and alpha components demonstrated the same estimates not only within each neurological state, but also among the different states. These results indicate that the theta and alpha components may be caused by similar dynamic processes. We conclude that the brain function underlying the ictal EEG has a simple mechanism. Several heterogeneous dynamic systems play important roles in the generation of EEG. Received: 10 December 1999 / Accepted in revised form: 8 May 2000     

Correlation between the Activity of Dopaminergic Neurons of the Ventral Tegmentum and Spectral Power of the EEG Rhythms in Awake Cats

We studied correlations between the frequency of background impulse activity (BIA) of dopaminergic (DAergic) neurons of the ventral tegmentum (VT) and spectral power (SP) of the frequency components of EEG samples recorded in awake cats. The EEG was recorded monopolarly (electrodes were fixed in the cranial bones) from the frontal, occipital, and right and left temporal regions of the cortex. In a great majority of the cases, the BIA frequency of VT DA-ergic neurons demonstrated significant positive correlations with changes in the SPs of the alpha and beta EEG rhythms. The closest correlations of the spiking frequency of DA-ergic cells with the SP of the alpha rhythm was observed in the occipital region, while those with the beta SP were found in the frontal area. Correlations of the activity of DA-ergic neurons with the SPs of the alpha and beta rhythms in the left temporal cortical zone were closer, as compared with those in the symmetrical right zone. Correlations of the SPs of the delta, theta, and gamma EEG components with the discharge frequency of VT DA neurons were of opposite directions, and in most cases such correlations did not reach the level of significance. The results of this study show that, in some cases, specific EEG patterns can be considered indicators of the state of the cerebral VT DA-ergic system. Neirofiziologiya/Neurophysiology, Vol. 40, No. 4, pp. 359–367, July–August, 2008.     

EEG signature and phenomenology of alpha/theta neurofeedback training versus mock feedback

Alpha/theta (a/t) neurofeedback training has in the past successfully been used as a complementary therapeutic relaxation technique in the treatment of alcoholism. In spite of positive clinical outcomes, doubts have been cast on the protocol's specificity when compared to alternative relaxation regimes. This study investigated the basic tenet underlying the a/t training rationale, that accurate a/t feedback representation facilitates the generation of these frequency components. Two groups of healthy volunteers were randomly assigned to either (a) real contingent a/t feedback training or (b) a noncontingent mock feedback control condition. The groups were compared on measures of theta/alpha (t/a) ratios within and across training sessions, as well as activational self-report scales after each session. The contingent a/t feedback group displayed significant within-session t/a ratio increments not evident in the mock control group, as well as higher overall t/a ratios in some but not all of the training sessions. No differences were found between the groups in terms of subjective activational phenomenology, in that both groups reported significantly lower levels of activation after training sessions. The data demonstrate that irrespective of considerations of clinical relevance, accurate a/t neurofeedback effectively facilitates production of higher within-session t/a ratios than do noncontingent feedback relaxation.     

Changes in EEG Power Spectra During Biofeedback of Slow Cortical Potentials in Epilepsy

The goal of the study was to explore parallel changes in EEG spectral frequencies during biofeedback of slow cortical potentials (SCPs) in epilepsy patients. Thirty-four patients with intractable focal epilepsy participated in 35 sessions of SCP self-regulation training. The spectral analysis was carried out for the EEG recorded at the same electrode site (Cz) that was used for SCP feedback. The most prominent effect was the increase in the 2 power (6.0–7.9 Hz) and the relative power decrement in all other frequency bands (particularly 1, 2, and 2) in transfer trials (i.e., where patients controlled their SCPs without continuous feedback) compared with feedback trials. In the second half of the training course (i.e., sessions 21–35) larger power values in the , , and bands were found when patients were required to produce positive versus negative SCP shifts. Both across-subject and across-session (within-subject) correlations between spectral EEG parameters, on the one hand, and SCP data, on the other hand, were low and inconsistent, contrary to high and stable correlations between different spectral variables. This fact, as well as the lack of considerable task-dependent effects during the first part of training, indicates that learned SCP shifts did not directly lead to the specific dynamics of the EEG power spectra. Rather, these dynamics were related to nonspecific changes in patients' brain state.     

Interrelations between Peculiarities of the Motivational Sphere of a Personality and Characteristics of the Current EEG

In a group of 70 adult subjects of both sexes, we estimated the levels of the need for achievement and its motivation (interpreted as generalized characteristics of the state of the motivational sphere of a personality and diagnosed using questionnaires of Orlov and Mehrabian) and examined the correlations of these estimates with spectral powers (SPs) of the frequency components (rhythms) of the current background EEG (С3 and С4 leads according to the 10–20 system). Despite the fact that naturally high interindividual variability exists, high estimates of the need for achievement correlated with medium values of the SPs of most EEG frequency components (δ, θ, α, and β₁ rhythms), low SPs of the β₂ and γ rhythms, and higher values of the coefficient of reactivity (CR) of the α rhythm. A high level of the need for achievement corresponded to higher SPs of the θ and γ rhythms and high CR of the α rhythm, a medium SP of this EEG component, and lower SPs of the δ and β rhythms. The coefficient of interhemisphere asymmetry of the α rhythm was the highest at low values of the studied psychological indices. Interrelations that we found in our study can be explained as follows: both the characteristics of the need for achievement and motivation typical of a certain personality and the amplitude parameters of the EEG rhythms observed in this individual depend significantly on genetically determined factors (in particular, on neurochemical ones). These peculiarities of neurodynamic constitution of the individual are, to a considerable extent, due to the specificity of organization and functioning of a few neurotransmitter (aminergic, in particular) and neurohumoral systems. Neirofiziologiya/Neurophysiology, Vol. 41, No. 1, pp. 61–69, January–February, 2009.     

Correlation between level of aggressiveness of personality and characteristics of EEG frequency components

In a group of 80 adults of both sexes, we studied the correlation between the characteristics of aggressiveness of the individual (diagnosed using the Buss-Durkee questionnaire) and parameters of the frequency components (rhythms) of EEG recorded in the resting state from leads C3 and C4 according to the 10–20 system. Despite the natural high interindividual variability, the higher spectral powers of nearly all EEG frequency components (δ-, θ-, α-, and β rhythms) and coefficient of reactivity of the α rhythm corresponded in general to lower indices on the scales of the Buss-Durkee questionnaire and smaller values of the index of aggressiveness and index of hostility. These correlations probably reflect a significant dependence of both characteristics of aggressiveness of personality and amplitude parameters of the EEG rhythms on hereditary factors. Both these aspects of the neurodynamic constitution of the individual are to a significant extent determined by the specificity of organization and functioning of a few neurotransmitter (in particular, aminergic) and neurohumoral systems. Neirofiziologiya/Neurophysiology, Vol. 38, Nos. 5/6, pp. 448–457, September–December, 2006.     

Correlations between the content of toxic and essential metals in the organism and characteristics of EEG potentials in youths under conditions of an urban environment

In 18-to 19-year-old students, the content of a number of microelements, as well as of calcium, in biologically stable tissues (hair samples) was measured using X-ray fluorescent analysis. In the tested persons, we observed a certain deficit of main elements (calcium, copper, and zinc), while in some persons the levels of toxic lead and strontium were exceeded. Correlation analysis of the parameters of EEG potentials (current EEG and evoked and event-related potentials, EPs and ERPs, respectively) showed the existence of a few significant (or close to those) correlations of the spectral powers of some rhythms and derivatives of a few indices of the background EEG and more numerous cases of correlations of the parameters of EPs and ERPs (latencies and amplitudes) with the contents of the studied elements. The physiological importance of metals, according to the number of characteristics of EEG potentials that correlate with their contents, can be arranged in descending order as follows: As, Zn > Ca > Cd > Pb > Sr. None of the studied parameters of EEG phenomena correlated with the level of copper. The strength of correlations varied from weak to mild (0.29 < R < 0.50). The densest correlations were observed for the concentrations of toxic lead and cadmium. With respect to the characteristics of ERPs, some of the elements under study demonstrated synergism (e.g., lead and arsenic), while others were in an antagonistic relation (cadmium and calcium). Neirofiziologiya/Neurophysiology, Vol. 38, No. 2, pp. 167–174, March–April, 2006.     

The Effectiveness of Neurofeedback and Stimulant Drugs in Treating AD/HD: Part II. Replication

This study replicated T. R. Rossiter and T. J. La Vaque (1995) with a larger sample, expanded age range, and improved statistical analysis. Thirty-one AD/HD patients who chose stimulant drug (MED) treatment were matched with 31 patients who chose a neurofeedback (EEG) treatment program. EEG patients received either office (n = 14) or home (n = 17) neurofeedback. Stimulants for MED patients were titrated using the Test of Variables of Attention (TOVA). EEG (effect size [ES] = 1.01–1.71) and MED (ES = 0.80–1.80) groups showed statistically and clinically significant improvement on TOVA measures of attention, impulse control, processing speed, and variability in attention. The EEG group demonstrated statistically and clinically significant improvement on behavioral measures (Behavior Assessment System for Children, ES = 1.16–1.78, and Brown Attention Deficit Disorder Scales, ES = 1.59). TOVA gain scores for the EEG and MED groups were not significantly different. More importantly, confidence interval and nonequivalence null hypothesis testing confirmed that the neurofeedback program produced patient outcomes equivalent to those obtained with stimulant drugs. An effectiveness research design places some limitations on the conclusions that can be drawn.     

Modifications of EEG Related to Directed Perception and Analysis of Olfactory Information in Humans

We recorded EEG in adult volunteers in the course of perception of smells of plant essential oils under conditions of directed attention. It was found that perception of olfactory information, even in the case of mild intensity of the smells inducing no aversive effects, correlates with noticeable changes in the EEG characteristics mostly typical of the reaction of nonspecific EEG activation induced by sensory stimulation and manifested in a decrease in the spectral power, SP, of low-frequency EEG components (6–10 Hz)). In addition, the SP of relatively high-frequency EEG components (11–25 Hz) increased; this effect was most pronounced in the occipital regions of the neocortex. Perception of the smells of essential oils was also accompanied by increases in the coherence of EEG oscillations, most intense in the β2 range (20–25 Hz). Such modifications were maximum in the left temporal/parietal region; this is interpreted as an indication of the special role of these cortical areas in the processes of interaction between the neocortical part of the olfactory analyzer and the respective structures of other analyzer systems. It is hypothesized that such interaction is necessary for the formation of a semantic image of the analyzed stimuli. Neirofiziologiya/Neurophysiology, Vol. 41, No. 1, pp. 70–78, January–February, 2009.     

Correlations between EEG Characteristics and Contents of Some Micro- and Macroelements (Lead,Strontium, and Calcium) in the Organism of 12- to 13-Year-Old Children Living in Ecologically Unfavourable Regions of Ukraine

In 12- to 13-year-old children, inhabitants of regions of Ukraine with high levels of industrial contamination, we found higher contents of lead and calcium, as compared with the upper limits of the norm, in samples of biologically stable tissues (hairs). Concentrations of strontium were within the limits of reference values. Correlation analysis of the EEG frequency components vs levels of the above-mentioned metals demonstrated the existence of significant (or close to significant) relations between normalized spectral powers of the rhythms of background EEG recorded at different functional states (eyes open/closed, solving an arithmetic task) and concentrations of these elements. According to the number of the correlations found and their strength, the order of significance of the effects of the above elements with respect to the pattern of EEG activity was the following: Ca > Sr > Pb. The intensity of significant correlations varied from mild to moderately strong (0.41 < r < 0.70). The tightest correlations with the levels of all elements were observed under conditions of cognitive loading (solving an arithmetic task). High-frequency EEG components (β1 and β2 rhythms) were found to be the EEG components most sensitive to the contents of the mentioned elements.