Biofeedback in optimizing psychomotor reactivity: II. The dynamics of segmental α-activity characteristics

To estimate the EEG predictors of successful training in the voluntary control of psychomotor reactivity, 29 healthy young (aged 22.3 ± 1.5 years) musical performers were examined. The estimation was carried out in terms of segmental α-activity analysis using a biofeedback session as an example, simultaneously stimulating the EEG α rhythm and decreasing the muscle tone. On the first day of the study, the musicians followed instructions for the voluntary control of comfortable finger motor activity when performing musical passages for the right hand during a standard performance practice (without any use of an adaptive feedback). On the second day, the muscle tone and the power of the EEG α rhythm were voluntarily controlled in the context of a biofeedback technology. The analysis of the unsteady EEG segmentation showed that the dynamics of changes in the coherence and segmental characteristics of the α activity were the same for both effective biofeedback training and the standard successful performance practice: an increase in the α-rhythm coherence, an increase in the lifetime of α spindles, and a decrease in their amplitude variability. The results obtained are discussed in terms of the formation and dissociation of neuron ensembles in central mechanisms of optimal psychomotor functioning.     

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.     

Effect of voluntary EEG α power increase training on heart rate variability

The following objectives were set out to study the effect of EEG α power increase training on the heart rate variability (HRV) as an index of the autonomic regulation of cognitive functions: (1) to establish the interrelation between a voluntary increase in the α power in the individual upper α band and the HRV and related characteristics of cognitive and emotional spheres; (2) to determine the nature of the relationship between the α-activity indices and HRV depending on the resting α-frequency EEG pattern; and (3) to study how the individual α-frequency EEG pattern is reflected in the HRV changes as a result of biofeedback training. Psychometric indices of cognitive performance and the characteristics of EEG α activity and HRV were recorded in 27 healthy men 18–34 years of age before, during, and after ten training sessions of a voluntary increase in α power in the individual upper α band with the eyes closed. To determine the biofeedback effect in the α power increase training, the data of two groups were compared: the experimental, with a real biofeedback (14 subjects), and the control, with a sham biofeedback (13 subjects). The follow-up effect of the training was assessed one month after its end. The results showed that α biofeedback training increased the resting α frequency, improved cognitive performance, reduced psychoemotional stress, and increased HRV only in the subjects with a low baseline α frequency. In the subjects with a high baseline resting α frequency, the α biofeedback training had no effect on the resting α power and cognitive performance but reduced the HRV (judging by the pNN ₅₀ parameter). The positive correlation between the α peak frequency and HRV in subjects with initially low α frequency and the negative correlation in the subjects with a high baseline α frequency explains the opposite biofeedback effects on HRV in subjects with low and high α frequency. From the theoretical standpoint, the results of this study contribute to understanding the mechanisms of heart-brain neurovisceral relationships and their effect on the cognitive performance. From the applied standpoint, they suggest that EEG biofeedback can be used for improving autonomic regulation in healthy subjects and the development of individual approaches to the development of the biofeedback technology, which can be used both in clinical practice for treatment and rehabilitation of psychosomatic syndromes and in educational training.     

Training for voluntarily increasing individual upper α power as a method for cognitive enhancement

In order to estimate the effect of simultaneous α EEG stimulating and electromyogram (EMG) decreasing biofeedback training on the α activity and cognitive functions, fluency, accuracy, and flexibility during cognitive tasks, as well as α-activity characteristics before, during, and after ten training sessions of voluntarily increasing α power in an individual upper α range with the eyes closed were studied in 27 healthy men aged 18–34 years. To isolate the biofeedback effect in training for the α power increase, data on two groups of subjects were compared: an experimental group (14 subjects) with true biofeedback and a control group (13 subjects) with sham biofeedback. Follow-up testing was performed one month after the end of training to estimate the stability of the effect. The results showed that the training for the upper α power increase using biofeedback increased the frequency, width, and power in an individual upper α range at rest and improved cognitive performance only in subjects with a low baseline α frequency. Conversely, sham biofeedback training (without the feedback signal) increased the α power, though less efficiently, only in subjects with a high baseline α frequency, this increase was not accompanied by improved cognitive performance. The biofeedback α training eliminated the decrease in the α amplitude in response to a cognitive task after the biofeedback training course, this effect being preserved within one month. It may be concluded that α EEG-EMG biofeedback training can be used for improving cognitive processes in healthy subjects, as well as for prognostic purposes in clinical practice and in the brain-computer interface technology.     

Correction of functional disturbances during pregnancy by the method of adaptive EEG biofeedback training

The applicability and efficiency of the electroencephalogram (EEG)-based method of biofeedback (BFB) training in correcting functional disorders in pregnancy have been evaluated in an obstetric/gynecological clinic in 65 pregnant women. Each of them took part in 2–12 examinations, which differed in voluntarily regulated EEG rhythm (a decrease in the θ, an increase in the α, or a decrease in the β rhythm), left-or right-hemispheric location of the EEG derivations, and the duration of the delay (3 or 30 s) of auditory feedback stimuli. As compared to the baseline, the most distinct and significant changes were observed in the α and θ rhythms during medical procedures, testifying to a general relaxing effect of the EEG BFB. The greatest number of successful trials (83.3 ± 4.4%) was observed for the BFB sessions aimed at decreasing the θ activity, and the lowest number (32.0 ± 6.7%), for the attempts at decreasing the EEG β rhythm. Voluntary control of the α rhythm of the EEG yielded a moderate number of successful trials (63.7 ± 5.3%), but it was characterized by the lowest efficiency (demonstrating minimal differences in positive changes in the functional state between successful and unsuccessful trials). The comparatively low effectiveness of voluntary BFB control of the α rhythm may have been determined by its high heterogeneity and suggests the necessity of using more narrowband EEG components in BFB sessions.     

EEG alpha indices depending on the menstrual cycle phase and salivary progesterone level

The effects of neurohumoral status on the EEG α activity were studied in 78 women (18–27 years old) during one or two menstrual cycles using a within-subjects design. The psychometric and electroencephalographic (EEG) indices of α waves, basal body temperature, and salivary progesterone level were monitored every two or three days. The menstrual and follicular recording sessions occurred before the basal temperature rise caused by ovulation, the luteal recording session occurred after the increase in progesterone level by more than 20% compared to the day before, and the premenstrual recording sessions occurred after the decrease in progesterone level by more than 20% compared to the day before. The EEG, electromyographic (EMG) and electrocardiographic (ECG) characteristics of cognitive efficiency and psycho-emotional tension were recorded at rest and during task performance. The experiments were started in the menstrual phase in half the subjects and in the luteal phase in the other half. Psychometric characteristics, EEG α activity, EMG and ECG indices were compared for all the five phases at rest and in response to cognitive task performance. The results have shown that all psychometric and α EEG indices are menstrual-cycle-dependent. The maximum cognitive fluency, α peak frequency, α band width, and power in the α₂ frequency band are observed in the luteal phase, while the maximum power in the low-frequency α₁ band, as well as visual and cognitive activation calculated from α power reduction, are observed in the follicular phase of the menstrual cycle. The hypothesis that EEG α activity depends on the neurohumoral status is supported by the positive correlation of salivary progesterone level with the α peak frequency and the power in the α₂ band and its negative correlation with the power in the α₁ band. It is concluded that psycho-physiological recording sessions in women must be carried out with due consideration of the menstrual cycle phase.     

EMG biofeedback and discriminative muscle control

The awareness model of biofeedback suggests that training teaches new skills or enhances performance at old skills, while the cognitive or feed-forward models suggest that biofeedback brings attention to the response of interest but does not actually increase task skill. In a test of the predictions made by these models, subjects were tested on one or more cross-modal matching tasks, provided brief training, and retested on the task(s). Thirty subjects participated in integer-matching tasks in which they were instructed to produce various levels of frontalis activity corresponding to the levels of a ratio scale. Forty-five subjects participated in a tone-matching task in which they tried to match their frontalis tension to the pitch of a tone. The results indicated that the groups receiving biofeedback training improved at the more difficult integer task and at the tone task. Subjects performed better on the integer tasks than at the tone task. Our findings suggest that an awareness model accounts for changes occurring during biofeedback training. However, an awareness model may be applicable only for tasks of moderate difficulty; for relatively easy tasks, a feed-forward model may be more appropriate. The clinical utility of cross-modal matching tasks is also described.     

EMG biofeedback and discriminative muscle control

The awareness model of biofeedback suggests that training teaches new skills or enhances performance at old skills, while the cognitive or feed-forward models suggest that biofeedback brings attention to the response of interest but does not actually increase task skill. In a test of the predictions made by these models, subjects were tested on one or more cross-modal matching tasks, provided brief training, and retested on the task(s). Thirty subjects participated in integer-matching tasks in which they were instructed to produce various levels of frontalis activity corresponding to the levels of a ratio scale. Forty-five subjects participated in a tone-matching task in which they tried to match their frontalis tension to the pitch of a tone. The results indicated that the groups receiving biofeedback training improved at the more difficult integer task and at the tone task. Subjects performed better on the integer tasks than at the tone task. Our findings suggest that an awareness model accounts for changes occurring during biofeedback training. However, an awareness model may be applicable only for tasks of moderate difficulty; for relatively easy tasks, a feed-forward model may be more appropriate. The clinical utility of cross-modal matching tasks is also described.This paper is based on a thesis conducted by the second author under the direction of the first author. Portions of this paper were presented at the annual meeting of the Association for Applied Psychophysiology and Biofeedback, March 1989, San Diego.     

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.     

脑电生物反馈系统的研制和脑电α成分反馈的研究

本文介绍了我们研制的微机化脑电反馈系统.并报告了我们所进行的正常人脑电α成分生物反馈训练实验,证明了脑电生物反馈提升α成分比例的可行性.本文还论讨了国际上现行关于脑电α成分生物反馈研究中存在的问题,提出了有效的解决方法.     

Maintenance and generalization of 40-Hz EEG biofeedback effects

Maintenance of conditioning of 40-Hz EEG activity was investigated in six adults 1 to 3 years after they had experienced biofeedback training to increase 40-Hz EEG. Subjects were first retrained to alternately increase and suppress 40-Hz EEG. All six subjects achieved a preset performance criterion in 16–20 minutes. Five of these subjects also subsequently demonstrated significant control of 40-Hz EEG without feedback. The sixth subject did not demonstrate control after 76 minutes and four sessions of attempted retraining with feedback. Transfer of 40-Hz EEG control to a problem-solving task was tested in all subjects in a final session. Cognitive test items were presented and subjects were instructed to alternately increase and suppress 40-Hz EEG while solving the problems. Rates of 40-Hz EEG in suppression periods during problem solving were significantly greater than during suppression periods without problems. No significant differences in problem-solving performance were found comparing 40-Hz increase and suppression periods. This study supports previous research suggesting an association between 40-Hz EEG and mental activity, and suggests methods for further study of transfer of EEG biofeedback effects.     

Influence of Tonal Modulation in a Melodic Line on the Spectral Parameters of Human EEG

The influence of tonal modulation in pieces of music on the EEG parameters was studied. An EEG was recorded while subjects were listening to two series of fragments with modulations: controlled harmonic progressions and the fragments of classical musical compositions. Each series included modulations to the subdominant, the dominant, and the ascending minor sixth. The highly controlled and artistically impoverished harmonic progressions of the first series contrasted with the real music excerpts in the second series, which differed in tempo, rhythm, tessitura, duration, and style. Listening to harmonic progressions and musical fragments produced event-related synchronization in the α frequency band. Real musical fragments with modulation to the dominant generated lower synchronization in the α band as compared with other modulations. A lower decrease of synchronization in the α frequency band after listening was observed in the case of fragments of classical music compared with harmonic progressions.     

Biofeedback treatments of generalized anxiety disorder: Preliminary results

Forty-five individuals with generalized anxiety (38 with GAD as defined by DSM-III) were randomized to 4 treatment conditions or a waiting list control. Patients received 8 sessions of either frontal EMG biofeedback, biofeedback to increase EEG alpha, biofeedback to decrease EEG alpha, or a pseudomeditation control condition. All treated subjects showed significant reductions in STAI-Trait Anxiety and psychophysiologic symptoms on the Psychosomatic Symptom Checklist. Only alpha-increase biofeedback subjects showed significant reductions in heart rate reactivity to stressors at a separate psychophysiological testing session. Decreased self-report of anxiety was maintained at 6 weeks posttreatment.     

Cognitive brain–Computer interface and probable aspects of its practical application

A new type of brain-computer interface was elaborated. It considers a variety of brain activity parameters to determine the type of mental operation being performed at the moment. The corresponding algorithm previously developed in the lab was modified for real-time application. The possibility of interface application for cognitive skills training was investigated. In the proposed paradigm, as soon as the EEG spectral pattern was adequate for the current task, some clue to the solution was presented. As we supposed, such positive biofeedback should facilitate memorization of the current brain state. After just one learning session, the differences in EEG spectra, corresponding to two types of tasks, were concentrated in more narrow frequency ranges. It indicates a decrease in mental effort. Moreover, the majority of subjects succeeded in solving the tasks faster, which is evidence of increased efficiency. The developed interface could be used for the new type of training, based on objective features of brain activity.     

Respiratory Sinus Arrhythmia Feedback in a Stressed Population Exposed to a Brief Stressor Demonstrated by Quantitative EEG and sLORETA

Previous investigations of electroencephalograms during relaxation have identified increases in slow wave band power, correlations between increased levels of alpha activity with lower levels of anxiety, and autonomic changes characterized by otherwise documented decreased sympathetic activity. This study was carried out to determine the overall changes in quantitative electroencephalographic activity and the current source as a result of an acute session of respiratory sinus arrhythmia (RSA) biofeedback in a population of subjects experiencing stress. This study’s findings provide physiological evidence of RSA feedback effect and suggest that RSA training may decrease arousal by promoting an increase of alpha band frequencies and decrease in beta frequencies overall and in areas critical to the regulation of stress. It was of interest that novices could achieve these objective alterations in EEG activity after minimal training and intervention periods considering that the previous literature on EEG and meditative states involve experienced meditators or participants who had been given extensive training. Additionally, these effects were present immediately following the training suggesting that the intervention may have effects beyond the actual practice.     

EEG changes in the early postoperative period after excision of tumors of basal-diencephalic location

Changes in the EEG spectral coherence characteristics were analyzed in 60 patients in the early postoperative period after the excision of basal-diencephalic tumors (located in the hypothalamic and thalamic structures) using different surgical approaches (transcallosal, subfrontal, and transnasal). On the first day after surgery, all the patients exhibited a significant decrease in the Δ, θ, and α rhythms compared to the preoperative recordings. Decreased interhemispheric and increased intrahemispheric coherent relations were found simultaneously with changes in the EEG power in patients operated on through the transcranial approach. Within 7–10 days, the pathological structure of the functional relations changed reciprocally. In the case of the transnasal approach, the patients exhibited only an impairment of interhemispheric interaction in the frontocentral areas on the first day after surgery. A decrease in the interhemispheric and an increase in the intrahemispheric coherent relations were determined by the irritation of the pathologically changed hypothalamic and thalamic structures, rather than the dissection of the corpus callosum.     

Development of psychomotor tempó (tapping speed and stability) and EEG alpha frequency in 7 to 15-years-old children

The psychomotor tempo (tapping) and its relation to alpha frequency was investigated in 100 7- to 15-year-old children. The frequency of alpha rhythm increased in proportion to age, and the maximum and preferential tapping frequencies revealed an increasing tendency, too. Mainly the preferential tapping frequency correlated with the age-dependent increment of EEG alpha frequency. Simultaneously, the variability of the tapping frequency decreased. During a phase of relatively stable tapping performance regular fluctuations in the tapping frequency occurred with a period duration between 0.67 and 13.3 s. These oscillations of the motor activity developed during ontogenesis: The slow fluctuations were found in all groups, whereas those with shorter periods were best pronounced in the older children. The development of EEG and psychomotor indices are assumed to be based on the morphological and functional maturation of the developing brain. Therefore, they may be used as a tool to assess the normal and disturbed brain development.     

Neuroimaging Study of Alpha and Beta EEG Biofeedback Effects on Neural Networks

Neural networks interaction was studied in healthy men (20–35 years old) who underwent 20 sessions of EEG biofeedback training outside the MRI scanner, with concurrent fMRI–EEG scans at the beginning, middle, and end of the course. The study recruited 35 subjects for EEG biofeedback, but only 18 of them were considered as “successful” in self-regulation of target EEG bands during the whole course of training. Results of fMRI analysis during EEG biofeedback are reported only for these “successful” trainees. The experimental group (N?=?23 total, N?=?13 “successful”) upregulated the power of alpha rhythm, while the control group (N?=?12 total, N?=?5 “successful”) beta rhythm, with the protocol instructions being as for alpha training in both. The acquisition of the stable skills of alpha self-regulation was followed by the weakening of the irrelevant links between the cerebellum and visuospatial network (VSN), as well as between the VSN, the right executive control network (RECN), and the cuneus. It was also found formation of a stable complex based on the interaction of the precuneus, the cuneus, the VSN, and the high level visuospatial network (HVN), along with the strengthening of the interaction of the anterior salience network (ASN) with the precuneus. In the control group, beta enhancement training was accompanied by weakening of interaction between the precuneus and the default mode network, and a decrease in connectivity between the cuneus and the primary visual network (PVN). The differences between the alpha training group and the control group increased successively during training. Alpha training was characterized by a less pronounced interaction of the network formed by the PVN and the HVN, as well as by an increased interaction of the cerebellum with the precuneus and the RECN. The study demonstrated the differences in the structure and interaction of neural networks involved into alpha and beta generating systems forming and functioning, which should be taken into account during planning neurofeedback interventions. Possibility of using fMRI-guided biofeedback organized according to the described neural networks interaction may advance more accurate targeting specific symptoms during neurotherapy.     

Electroencephalographic biofeedback of SMR and beta for treatment of attention deficit disorders in a clinical setting

Six children were provided with long-term biofeedback and academic treatment for attention deficit disorders. Their symptoms were primarily specific learning disabilities, and, in some cases, there were varying degrees of hyperkinesis. The training consisted of two sessions per week for 10 to 27 months, with a gradual phase-out. Feedback was provided for either increasing 12- to 15-Hz SMR or 16- to 20-Hz beta activity. Inhibit circuits were employed for blocking the SMR or beta when either gross movement, excessive EMG, or theta (4-8 Hz) activity was present. Treatment also consisted of combining the biofeedback with academic training, including reading, arithmetic, and spatial tasks to improve their attention. All children increased SMR or beta and decreased slow EEG and EMG activity. Changes could be seen in their power spectra after training in terms of increased beta and decreased slow activity. All six children demonstrated considerable improvement in their schoolwork in terms of grades or achievement test scores. None of the children are currently on any medications for hyperkinetic behavior. The results indicate that EEG biofeedback training, if applied comprehensively, can be highly effective in helping to remediate children who are experiencing attention deficit disorders.     

Effects of voluntary control of the functional state on the organization of cortical processes during mnemenic activity in schoolchildren aged nine to ten years

In schoolchildren aged nine to ten years, the analysis of EEG indices (spectral power density, the function of coherence in the α band) of different cortex regions in four experimental situations—quiet wakefulness, mnemenic activity, relaxation, and mnemenic activity in the postrelaxation period—was performed. In the mnemenic activity situations, a task for determining the short-term auditory-speech memory span was used. A positive effect of relaxation on the efficiency of mnemenic activity expressed in an increase in the short-term memory span was found. Comparison of groups formed according to the increase in the memory span showed differences in the dynamics of coherence indices. Only in children with a pronounced postrelaxation increase in the memory span in the situation of mnemenic activity was an increase in coherence in the high-frequency subrange of the α band of the EEG detected, whose functional significance is related to selective inhibition.