Stabilometric Biofeedback Training in Cognitive and Affective Function Improvement. Contribution of the Russian Scientific School. Part II.

This review is the second part of the critical analysis of recent papers of Russian and other authors devoted to the study of the stabilometric parameters in postural control biofeedback training and rehabilitation, associated with psychological functions. The review presents the studies of postural control features in chronic pain syndrome, chronic fatigue syndrome, Parkinson's disease, multiple sclerosis, and depression. The leading role of Russian researchers in the development and application of stabilometric biofeedback in the training of optimal functioning, rehabilitation, and correction of neurological disorders is noted. The paradigm of stabilometric biofeedback training of the cognitive and affective functions is offered.

Psychophysiological Indicators of Postural Control. Contribution of the Russian Scientific School. Part I.

This article aimed to systematically review the published results of studies of psychophysiological mechanisms of posture maintenance and identify the key factors that influence the effectiveness of postural control. The recommendations of "Preferred Reporting Elements for Systematic Reviews and Meta-Analyzes" (PRISMA) were followed for the review. The results were classified, taking into account the target psychophysiological mechanisms and factors affecting postural control. The article presents the theoretical and empirical results of the Russian scientific school of research on the role of support afferentation in the sensorimotor mechanisms of cognitive and postural functions. Due to the limited number of randomized studies found, it was impossible to make meta-analytic comparisons, so the literature analysis was carried out only qualitatively. Meanwhile, our systematic review provides promising information about possible relationships between stabilometric and psychological indicators of postural control, which have theoretical significance and application in the correction and training of posture control. However, more thorough research is needed to overcome the methodological shortcomings that we have encountered in our qualitative analysis.

Psychophysiological Analysis of Thymoleptic Effects of Xenon in Humans.

This pilot study was aimed at evaluation of the translational potential of xenon as a potential antidepressant. In placebo-controlled double-blind study, 14 healthy right-handed volunteers were randomly assigned to 15-min inhalation session of either gas mixture with xenon (25%Хе/30%О2/45%N2) or placebo (70%N2/30%О2) with simultaneous recording of 64-channel EEG. To assess the dynamics and nature of emotional activation in response to xenon and placebo, we analyzed both the intensity of positive and negative emotions and individual alpha peak frequency (iAPF) of EEG. We found that xenon in sub-anesthetic doses promoted positive emotional arousal, and that emotional response to xenon depended on individual neurophysiological endophenotype of alpha-activity (iAPF). The authors suggest that iAPF shifts can be used as a neurophysiological predictor of individual thymoleptic response to xenon.

Training of support afferentation in postmenopausal women.

We have recently shown a diminishing of the Menopause Index in old-aged women who underwent special training directed at the enhancement of support afferentation by increasing the plantar forefoot sensitivity (Bazanova et al., 2015). Based on these results we hypothesized, that purposeful training of support afferentation through stimulation of plantar graviceptors by Aikido practice will decrease excessive postural and psychoemotional tension not only in rest condition, but during cognitive and manual task performance too. Fluency of cognitive and motor task performance, EEG alpha power as an index of neuronal efficiency of cognitive control, amount of alpha power suppression as a visual activation measure and EMG power of forehead muscles as a sign of psychoemotional tension were compared in three groups of post-menopausal women: i) 8years training with forefeet support afferentation with Aikido practice (A), ii) 8years fitness training (F) and iii) no dedicated fitness training for past 8years (N). Simultaneous stabilometry, EEG, and frontal EMG recording were performed in sitting and standing up position in eyes closed and eyes open condition. Recording done at rest and while performing cognitive and finger motor tasks. We compared studied parameters between groups with one- and two-way analyses of variance (ANOVAs) with Bonferroni correction for multiple comparisons, followed by post hoc two-tailed unpaired t-tests. The fluency of tasks performance, EMG and alpha-EEG-activity displayed similar values in all groups in a sitting position. Center of pressure (CoP) sway length, velocity and energy demands for saving balance increased when standing up, more in group N than in groups F and A (all contrasts p values<0.002, η2>0.89). Post hoc t-tests showed increased fluency in standing in both Aikido (p<0.01) and Fitness (p<0.05) subjects in relation to untrained subjects. Increasing fluency in motor task performance was in parallel with enhancing the EEG alpha-2-power and decreasing EMG power only in A group (η2>0.77). Fluency in motor task and alpha EEG power decreased, but frontal EMG power increased in response to standing in untrained women (group N) and did not change in F group. Post hoc t-tests showed that EEG amount of alpha-2 power suppression in response to visual activation and frontal EMG power was lower in A than F and N groups (p<0.004) during motor task performance in the standing position. These results were interpreted as showing that training of forefoot plantar surface sensitivity in postmenopausal women decreases levels of psychoemotional tension and increases cognitive control caused by the psychomotor and postural challenges. Thus, Aikido training aimed at learning coordination between manual task performance and balance control by increasing the plantar support zones sensation decreases the cost of maintained vertical position and dependence of motor coordination on visual contribution.

[Stabilometry, Electromyography and Electroencephalography in Postmenopausal Women after Training of the Leg Support Sensation].

Ageing, lack of physical activity and sedentary lifestyle cause disorders of the sensorimotor system of postural control. The role of support afferentation in the changes in cortical activity in balance impairments has not been studied yet. The purpose of this study was to investigate the changes in the stabilographic parameters of the body center of gravity, alpha activity indices of the electroencephalography (EEG) and electromyographic (EMG) measurements of forehead muscle tone in response to visual activation in standing and sitting positions in postmenopausal women after and without training of leg support sensation (LSS) The variables were compared between 3 groups: Group A (n = 12, age: 66 ± 9 years)--women who have trained LSS with the help of Aikido techniques for 8 years; group F (n = 12, age: 65 ± 6 years)--women who have attended Fitness training for 8 years; group N (n = 11, age: 66 ± 7 years)--women who have not taken physical exercises for the last 8 years. It was found that in group N a change in body position from "sitting" to "standing" leads to a much greater increase in the area of stabilogram and in the energy expenditure needed to maintain the bal- ance than in groups A and F. Posture changes from sitting to standing position increases the tension of the forehead muscles and the suppression of alpha-1-amplitude, but decreases the power in high- and low-frequency alpha-band of EEG and the width of alpha-band in group N. In women ofgroup F the posture change does not result in an increase in EMG and signs of activation or tension in EEG; in group A it leads to a decrease of visual activation indices and psychoemotional tension and to an increase in power in alpha-2-band which is a sign of neuronal efficiency. Basing on these data, we can conclude that training focused on support afferentation in postmenopausal women decreases the psychoemotional tension and increases neuronal efficiency ofsensorimotor integration of postural control system and can be used in the prevention of falls in elderly people.

[EEG alpha indices in dependence on the menstrual cycle phase and salivary progesterone].

The effects of the neurohumoral status on the EEG alpha - activity indices were studied in a within-subject design with 78 women aged 18-27 years during 1-2 menstrual cycle. Psychometric and EEG indices of alpha waves basal body temperature, saliva progesterone and cortisol level were monitored every 2-3 days. Menstrual and follicular recording sessions occurred before the ovulatory temperature rise, luteal recording session--after increasing progesterone level more than 20% respect to previous day and premenstrual sessions after decreasing progesterone level more that 20% respect to previous day. The design consisted of rest and task periods EEG, EMG and ECG recordings. Half the subjects began during their menstrual phase and half began during their luteal phase. All 5 phases were compared for differences between psychometric features EEG alpha activity, EMG and ECG baseline resting levels, as well as for reactivity to cognitive task. The results showed menstrual phase differences in all psychometric and alpha EEG indices. The cognitive fluency, alpha peak frequency, alpha band width, power in alpha-2 frequency range are maximal at luteal, alpha visual activation and reactivity to cognitive task performance--at follicular phase. The hypothesis that the EEG alpha activity depends on the hormonal status supported by the positive association salivary progesterone level with the alpha peak frequency, power in the alpha-2 band and negative--with the power of the alpha-1 band. According these results, we conclude that psycho-physiological recording sessions with women might be provided with a glance to phase of menstrual cycle.

Interpreting EEG alpha activity.

Exploring EEG alpha oscillations has generated considerable interest, in particular with regards to the role they play in cognitive, psychomotor, psycho-emotional and physiological aspects of human life. However, there is no clearly agreed upon definition of what constitutes 'alpha activity' or which of the many indices should be used to characterize it. To address these issues this review attempts to delineate EEG alpha-activity, its physical, molecular and morphological nature, and examine the following indices: (1) the individual alpha peak frequency; (2) activation magnitude, as measured by alpha amplitude suppression across the individual alpha bandwidth in response to eyes opening, and (3) alpha "auto-rhythmicity" indices: which include intra-spindle amplitude variability, spindle length and steepness. Throughout, the article offers a number of suggestions regarding the mechanism(s) of alpha activity related to inter and intra-individual variability. In addition, it provides some insights into the various psychophysiological indices of alpha activity and highlights their role in optimal functioning and behavior.

[The response of EEG activation in different neurohumoral conditions].

In order to examine under what neurohumoral condition response to the usual opening of the eyes is an incentive for the activation, electroencephalographic, electrocardiographic and electromyographic characteristics of the eyes open reaction in relation to the psychometric indicators of emotional stress and cognitive performance were recorded in 59 healthy women aged 18-27 every 2-3 days for 1-2 menstrual cycles, established in accordance with the morning levels of progesterone. For excluding NOVELTY factor influence one 29 women started monitoring at menstrual phase and other 30--at luteal phase of menstrual cycle. 30 women participated in a one-time monitoring, in which the relationship of these parameters with the current level of progesterone and cortisol in saliva was studied. Two factors ANOVA showed that the depth of the power suppression and the width of the individually determined low frequency alpha EEG range on follicular is more than on the luteal phase of the menstrual cycle of women and are influenced the NOVELTY. "Berger effect" indices of the upper alpha range are not changed depending on the neurohumoral status. Depth of the amplitude decrease and width of merely low-frequency alpha band could predict the activation in the eyes open response due to unidirectional changes and relationship to vegetative and hormonal characteristics of the activation. It was firstly established that eyes opening is an incentive factor to the activaition only when neurohumoral state corresponds to the follicular phase of the women mensrual cycle. This study reviles the dependence of the neuronal and vegetative activation mechanisms of the individual alpha frequency profile EEG and neurohumoral status.

[Voluntary alpha-power increasing training impact on the heart rate variability].

In order to study the effect of the alpha EEG power increasing training at heart rate variability (HRV) as the index of the autonomic regulation of cognitive functions there were follow tasks: (1) to figure out the impact of biofeedback in the voluntary increasing the power in the individual high-frequency alpha-band effect on heart rate variability and related characteristics of cognitive and emotional spheres, (2) to determine the nature of the relationship between alpha activity indices and heart rate variability, depending on the alpha-frequency EEG pattern at rest (3) to examine how the individual alpha frequency EEG pattern is reflected in changes HRV as a result of biofeedback training. Psychometric indicators of cognitive performance, the characteristics of the alpha-EEG activity and heart rate variability (HRV) as LF/HF and pNN50 were recorded in 27 healthy men aged 18-34 years, before, during, and after 10 sessions of training of voluntary increase in alpha power in the individual high-frequency alpha band with eyes closed. To determine the biofeedback effect on the alpha power increasing training, data subjects are compared in 2 groups: experimental (14) with the real and the control group (13 people)--with mock biofeedback. The follow up effect of trainings was studied through month over the 10 training sessions. Results showed that alpha biofeedback training enhanced the fluency and accuracy in cognitive performance, decreased anxiety and frontal EMG, increased resting frequency, width and power in individual upper alpha range only in participants with low baseline alpha frequency. While mock biofeedback increased resting alpha power only in participants with high baseline resting alpha frequency and did change neither cognitive performance, nor HRV indices. Biofeedback training eliminated the alpha power decrease in response to arithmetic task in both with high and low alpha frequency participants and this effect was followed up over the month. Mock biofeedback training has no such effect. The positive correlation between the alpha-peak frequency and pNN50 in patients with initially low, but negative--those with high baseline alpha frequency explains the multidirectional biofeedback effects on HRV in low and high alpha frequency subjects. The individual alpha-frequency EEG pattern determines the effectiveness of the alpha EEG biofeedback training in changing heart rate variability, which provides a basis for predicting the results and develop individual approaches to the biofeedback technology implementation that can be used in clinical practice for treatment and rehabilitation of psychosomatic syndromes and in educational training.

[Cognitive efficiency and psychoemotional tension in the various menstrual cycle phases].

Characteristics of the cognitive and emotional spheres were recorded in 67 healthy women aged 18-25 years 9-12 times in 1-2 menstrual cycles. The relationship of psychophysiological indicators activity of progesterone and cortisol in saliva was studied using a single monitoring. Using within individual comparisons it was established that the level of the psychoemotional tension women is lowest, and the cognitive effectiveness--the highest in the luteal phase of the menstrual cycle, then other phases. The highest level of non-verbal creativity was marked on the ovulatory and luteal but the highest activation and audio sensitivity--on the follicular and ovulatory phases of the cycle. The Correlation analysis showed that the changes of psychophysiological characteristics during a cycle are connected with the changes in the level of progesterone. These results provide evidence of the psychophysiological characteristics dependence on the neurohumoral status and the need to consider the phase of the menstrual cycle in psychometric measurements of female subjects.

[Alpha power voluntary increasing training for cognition enhancement study].

With the aim simultaneous alpha EEG stimulating and EMG decreasing biofeedback training impact on the alpha-activity and cognitive functions 27 healthy male subjects (18-34 years) were investigated in pre- and post 10 training sessions of the voluntary increasing alpha power in individual upper alpha range. The accuracy of conceptual span task, fluency and flexibility in alternatives use task performance and alpha-activity indices were compared in real (14 participants) and sham (13 participants) biofeedback groups for the discrimination of the feedback role in training. The follow up effect oftrainings was studied through month over the training sessions. Results showed that alpha biofeedback training enhanced the fluency and accuracy in cognitive performance, increased resting frequency, width and power in individual upper alpha range only in participants with low baseline alpha frequency. While mock biofeedback increased resting alpha power only in participants with high baseline resting alpha frequency and did not change the cognitive performance. Biofeedback training eliminated the alpha power decrease in response to arithmetic task in both with high and low alpha frequency participants and this effect was followed up over the month. Mock biofeedback training has no such effect. It could be concluded that alpha-EEG-EMG biofeedback has application not only for cognition enhancement, but also in prognostic aims in clinical practice and brain-computer interface technology.

[Individual alpha peak frequency variability and reproducibility in various experimental conditions].

The test-retest study of the individual alpha peak frequency (IAPF) variability was provided in eyes closed and eyes open conditions in standard (8-12 Hz) and individual alpha band range in different brain areas in 96 healthy male subjects (aged 25-40). The pairwise comparisons showed that IAPF means are not different in the left and right hemisphere sites, in eyes closed and eyes open conditions, in standard and individual alpha range. Computed in the first 5 s after opening eyes fronto-central area IAPF mean was lower than in eyes closed condition. IAPF computed in individual alpha range in posterior area in eyes closed condition had the minimal variability and was the most reproducible in test retest investigation.

[Electroencephalogram alpha activity: modern interpretations].

This review of modem interpretations of nature and physiological significance of EEG alpha activity was inspired with the following aims: 1--alpha activity phenomena determination, 2--summering the experimental and theoretical data about the nature, origin and neurophysiological mechanisms of the alpha oscillations distribution, 3--description of the most famous brain alpha activity structure hypothesis, 4--presentation of authors hypothesis about EEG alpha activity indices as: 1--individual alpha peak frequency in parietal-occipital brain area, 2--alpha spindle features: length, amplitude variability and steepness, 3--reactivity to visual stimulations as: amount and time duration of amplitude suppression and frequency range width in which amplitude suppression is appeared.

Biofeedback in psychomotor training. Electrophysiological basis.

The influences of individual musical practice and the same practice supplemented with biofeedback using electrophysiological markers for optimum music-performing activity were studied in 39 music students. Traditional technical practice produced increases in integral EMG power and decreases in alpha activity in most of the students with initially low maximum alpha activity peak frequencies. Similar practice but combined with individual sessions of alpha-EEG/EMG biofeedback were accompanied by increases in the frequency, bandwidth, and activation responses of EEG alpha rhythms in all subjects, along with decreases in EEG integral power. The efficacy of training with biofeedback and the ability to experience psychomotor learning depended on the initial individual characteristics of EEG alpha activity.

[Biofeedback in psychomotor training. Electrophysiological bases].

Comparison of influence of usual musical practice and the same trainings but using biofeedback on electrophysiological and psychological markers of optimal psychomotor functioning in 39 students-musicians revealed that the obvious musical practice caused psychomotor pressure in most students (with initially low individual alpha peak frequency), whereas similar practice combined with an individualized session of alpha-EEG/EMG biofeedback was accompanied by increase of alpha-activity in all examinees and a decrease (reduction) of integrated EMG that indicated reaching of optimal psychomotor functioning. It appears that the psychomotor learning ability depends on the baseline individual alpha-activity. Individual alpha peak frequency was associated with fluency and efficiency of psychomotor performance, individual alpha band width--with plasticity and creativity, individual amount of alpha suppression in response to opening eyes--with the level of selfactualization. These alpha activity EEG indices correlated with efficiency of the biofeedback training.

Individual measures of electroencephalogram alpha activity and non-verbal creativity.

The aim of the present work was to study correlational interactions between individual measures of alpha-activity in the baseline electroencephalogram (maximum peak frequency, range width, depth of alpha activity desynchronization reactions, structural characteristics of alpha spindles) and measures of non-verbal intellect ("Fluency," "Originality," "Flexibility") in the Torrance test in 98 healthy male subjects. These studies provided the first demonstration that individuals with high alpha-rhythm maximum peak frequency values and prolonged alpha spindles were generally characterized by more "fluent" non-verbal intellect. In turn, high levels of originality and intellectual plasticity showed a significant association with a wider range of alpha activity and variability of alpha spindle amplitude. The highest levels of originality in solving non-verbal tasks were seen in subjects with the lowest values for individual alpha-activity peak frequencies. These measures of the alpha rhythm can be regarded as individual markers of the productivity, plasticity, and originality of non-verbal intellect.

[Individual alpha activity of electroencephalogram and nonverbal creativity].

The main objective of present correlational investigation was to clarify relationships between nonverbal creativity indices and individual electroencephalogram alpha activity indices: individual alpha peak frequency, alpha band width, magnitude of alpha desynchronization and alpha spindle indices such as duration, amplitude, variability and skewness. The EEG was recorded in 98 healthy male right-handed subjects. Scores of nonverbal creativity (i. e., fluency, originality, and flexibility) were assessed using the Torrance test of nonverbal performance. The study showed that fluency in creative performance was associated with individual alpha peak frequency and alpha spindles duration, whereas originality and plasticity--with individual alpha band width and spindle amplitude variability. The findings also show that both highest and lowest individual alpha peak frequency indices are associated with enhanced scores of originality. It is suggested that individual alpha activity indices could be presented as individual predictors of fluency, plasticity and originality of nonverbal creativity.

[Learnability and individual frequency characteristics of EEG alfa activity].

The aim of the study was to determine correlations between individual frequency characteristics of EEG alfa activity (individual frequency of maximal alfa spectral peak IFMA, alfa band width--IABW, alfa spindle variability--AA, length--T, and steepness--S) and individual psychometric intelligence characteristics, calculated EEG-predictors, and real learnability indices. The subjects were 129 healthy men aged 16-50. The results show that people manifesting high IFMA along with low variability and the longest duration of alfa spindle, exhibit better performance in acquiring empiric knowledge. The best learnability is a distinctive feature of people with the highest IFMA and the widest IABW.