Behavioral and electroencephalographic correlates of 40-Hz EEG biofeedback training in humans

Two groups of eight adults successfully trained with biofeedback for increases in 40-Hz EEG responses in left or right hemispheres also demonstrated significant 40-Hz EEG increases during baseline periods, and increases in the contralateral hemisphere during training periods. No changes in heart rate, 40-Hz EMG, or 21- to 31-Hz beta, alpha, or theta EEG occurred over training days. Three subjects returning for additional training demonstrated suppression of 40-Hz EEG. A group of four subjects experiencing daily bidirectional training produced substantial within-session control of 40-Hz EEG but no changes over days. Data from posttraining tests without feedback for successful subjects in both groups indicated significant control of 40-Hz EEG responses in the initial parts of these sessions, and some correlated changes in other EEG responses. Measures of successful subjects' experiences during training and control tests indicated awareness of changes in subjective concomitants of EEG responses. This study suggests further strategies for research on behavioral correlates of EEG activity.     

Alpha enhancement,autonomic activation,and extraversion

Autonomic activation as reflected by heart rate, skin conductance, muscle tension, and T-wave amplitude of the electrocardiogram were registered during biofeedback training of EEG alpha. The group of 25 subjects showed significant enhancement of alpha but no systematic change in autonomic activation. This result was interpreted as supporting Eysenck's theory of two feedback loops for mediating cortical arousal. According to this theory, autonomic changes would not be expected to accompany changes in cortical arousal during resting conditions lacking emotional content and, therefore, not involving the visceral brain. Although some of the subjects who succeeded in increasing alpha experienced it as positive and others as strenuous, alpha change did not correlate significantly either with the dimension of extraversion, or with those of locus of control and neuroticism.     

Effects of Heart Rate Variability Biofeedback on EEG Alpha Asymmetry and Anxiety Symptoms in Male Athletes: A Pilot Study

Heart rate variability biofeedback (HRV-BFB) has been shown as useful tool to manage stress in various populations. The present study was designed to investigate whether the biofeedback-based stress management tool consisting of rhythmic breathing, actively self-generated positive emotions and a portable biofeedback device induce changes in athletes’ HRV, EEG patterns, and self-reported anxiety and self-esteem. The study involved 41 healthy male athletes, aged 16–21 (mean 18.34 ± 1.36) years. Participants were randomly divided into two groups: biofeedback and control. Athletes in the biofeedback group received HRV biofeedback training, athletes in the control group didn’t receive any intervention. During the randomized controlled trial (days 0–21), the mean anxiety score declined significantly for the intervention group (change-4 p < 0.001) but not for the control group (p = 0.817). In addition, as compared to the control, athletes in biofeedback group showed substantial and statistically significant improvement in heart rate variability indices and changes in power spectra of both theta and alpha brain waves, and alpha asymmetry. These changes suggest better self-control in the central nervous system and better flexibility of the autonomic nervous system in the group that received biofeedback training. A HRV biofeedback-based stress management tool may be beneficial for stress reduction for young male athletes.     

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.     

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.     

Role of Mood in Outcome of Biofeedback Assisted Relaxation Therapy in Insulin Dependent Diabetes Mellitus

Stressful life events and negative mood have been associated with elevated blood glucose and poor self-care in individuals with diabetes. The purpose of this controlled study was to determine the effect of mood state, specifically depression, anxiety, and daily hassles on the outcome of biofeedback assisted relaxation in insulin dependent diabetes mellitus. Eighteen subjects completed the study, nine in biofeedback assisted relaxation and nine in the control group. There were no significant group differences in blood glucose between those receiving biofeedback assisted relaxation and the subjects continuing usual care. Five of the nine experimental subjects and one of the nine control subjects were identified as succeeders according to an arbitrary criterion. Treatment failures were more depressed, more anxious, and took longer to complete the protocol than succeeders. Statistically significant correlations were found between high scores on inventories measuring depression, anxiety, and hassles intensity and higher blood glucose levels and smaller changes in blood glucose as a result of treatment. It is suggested that mood has an important impact on the response to biofeedback assisted relaxation. Further research is necessary to determine whether assessment of anxiety and depression followed by appropriate treatment where necessary should precede biofeedback assisted relaxation in insulin dependent diabetes.     

The Use of a Respiratory Rate Biofeedback Device to Reduce Dental Anxiety: An Exploratory Investigation

Anxiety experienced by individuals visiting the dental office to receive treatment is common. Evidence has shown biofeedback to be a useful modality of treatment for numerous maladies associated with anxiety. The purpose of the current pilot study was to investigate the use of a novel biofeedback device (RESPeRATE™) to reduce patients’ pre-operative general anxiety levels and consequently reduce the pain associated with dental injections. Eighty-one subjects participated in this study, forty in the experimental group and forty-one in the control group. Subjects in the experimental group used the biofeedback technique, while those in the control group were not exposed to any biofeedback. All subjects filled out a pre-injection anxiety survey, then received an inferior alveolar injection of local anesthetic. Post-injection, both groups were given an anxiety survey and asked to respond to four questions regarding the injection experience using a Visual Analog Scale (VAS). With the use of the respiratory rate biofeedback device, there was a significant reduction of negative feelings regarding the overall injection experience, as measured by a VAS. Our findings demonstrate that this novel biofeedback technique may be helpful in the amelioration of dental anxiety, and may help produce a more pleasant overall experience for the patient.     

Independent biofeedback self-regulation of EEG alpha and skin resistance

Skin resistance and EEG alpha were recorded concurrently during alpha biofeedback, in which the participant attempted to control alpha, and during skin resistance biofeedback, in which the participant attempted to control skin resistance. Alpha production changed significantly (p<0.001) during alpha biofeedback, indicating successful self-regulation of alpha, but did not change significantly during skin resistance biofeedback. Similarly, skin resistance changed significantly (p<.001) during skin resistance biofeedback but did not change significantly during alpha biofeedback. The results show independent control of alpha and skin resistance, and may reflect independent self-regulation of cognitive and somatic tension-relaxation systems.A longer version of this paper was presented at the meeting of the Biofeedback Society of America, Orlando, Florida, March 1977. Laurie Franconi, Tammy Johnson, and Dan Smith were invaluable during data collection. This research was supported in part by Grant #SMI76-04946 from the National Science Foundation to the author.     

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.     

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.     

Ocular and stabilization feedback: an evaluation of two EMG biofeedback control procedures

This study evaluated the adequacy of two novel EMG biofeedback control procedures. During a single training session, 36 subjects received either contingent EMG feedback from the frontal region (Veridical), contingent feedback for vertical eye movements (Ocular), or a feedback condition where the signal increased with deviations in any direction from baseline EMG levels (Stabilization). The results supported the use of Ocular but not Stabilization feedback as a control procedure in frontalis EMG biofeedback studies. Ocular feedback did not produce reductions in frontalis EMG but did lead to changes in subjective measures of nonspecific treatment effects that were at least comparable to those obtained with Veridical feedback. Stabilization subjects produced small but significant reductions in EMG, felt the most bored as a result of their feedback training, and were the most likely to rate themselves as having received false feedback. The implications of attribution theory and multiprocess relaxation theory for the evaluation of nonspecific treatment effects are discussed.     

Task-related stress and EEG alpha biofeedback

Establishing a contingency between stress and a physiological response is essential in biofeedback. The sensitivity of high alpha to contingent stress was investigated by manipulating conditions known to influence stress, such as the distribution, predictability, and controllability of stressful stimuli, and number of tasks performed. Forty subjects were divided into stress and non-stress groups. Within each group, one-half had the dual-task of anticipating and increasing alpha activity. The other half was initially instructed to only anticipate alpha and, later, had the dual task of anticipating and controlling alpha. No feedback training was included to distribute the task-related stressor and allowed the assessment of self-control. All of the stress manipulations significantly influenced the effects of stress on alpha production. The dual-task subjects produced less alpha and less self-control than did training with control phased in after subjects learned to anticipate alpha. Without stress, phased-in control produced highly significant increases in alpha production and self-control without feedback. The use of an alpha-contingent feedback paradigm and anticipation training was related to the therapeutic applications of alpha feedback to stress and anxiety.     

Heart Rate Variability Biofeedback Intervention for Reduction of Psychological Stress During the Early Postpartum Period

This study examined the effectiveness of heart rate variability (HRV) biofeedback intervention for reduction of psychological stress in women in the early postpartum period. On postpartum day 4, 55 healthy subjects received a brief explanation about HRV biofeedback using a portable device. Among them, 25 mothers who agreed to implement HRV biofeedback at home were grouped as the biofeedback group, and other 30 mothers were grouped as the control group. At 1 month postpartum, there was a significant decrease in total Edinburgh Postnatal Depression Scale score (P < 0.001) in the biofeedback group; this change was brought about mainly by decreases in items related to anxiety or difficulty sleeping. There was also a significant increase in standard deviation of the normal heartbeat interval (P < 0.01) of the resting HRV measures in the biofeedback group after adjusting for potential covariates. In conclusion, postpartum women who implemented HRV biofeedback after delivery were relatively free from anxiety and complained less of difficulties sleeping at 1 month postpartum. Although the positive effects of HRV biofeedback may be partly attributable to intervention effects, due to its clinical outcome, HRV biofeedback appears to be recommendable for many postpartum women as a feasible health-promoting measure after childbirth.     

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.     

Topographic EEG mapping of the relaxation response

The purpose of this study was to assess the central nervous system effects of the relaxation response (RR) in novice subjects using a controlled, within-subjects design and topographic EEG mapping as the dependent measure. Twenty subjects listened to a RR and control audiotape presented in a counterbalanced order while EEG was recorded from 14 scalp locations. TheRR condition produced greater (p<.0164) reductions in frontal EEG beta activity relative to the control condition. No significant differences were observed for any other frequency band or scalp region. These findings suggest that elicitation of the RR produces significant reductions in cortical activation in anterior brain regions in novice subjects.     

Biofeedback treatment of dysmenorrhea

Nine dysmenorrheic women were run in EMG and thermal biofeedback procedures with concurrent autogenic relaxation practice. Significant reductions in subjective estimates of symptomology associated with dysmenorrhea were noted in all subjects. EMG levels correlated positively with the reductions in symptoms. Thermal levels did not correlate with EMG. In fact no consistent patterns in thermal measures were noted. However, thermal biofeedback cannot be ruled out as an effective treatment for dysmenorrhea since reductions in symptoms occurred during thermal biofeedback training. Another significant aspect of the present study is the effectiveness of long treatment procedures. A six month period was employed and significant reductions in symptoms were noted following two months of biofeedback treatment. Finally, the importance of beginning biofeedback treatment prior to onset of menstrual symptoms is indicated.     

Cardiac sympathetic and parasympathetic activity during self-regulation of heart period

Fourteen subjects attempted to increase and 15 attempted to decrease cardiac interbeat interval (IBI) while being provided with biofeedback of IBI, T-wave vector magnitude (TWVM), or respiratory sinus arrhythmia (RSA). Subjects in both groups showed directional change in IBI relative to a tracking control task, but the three types of feedback did not differentially affect performance. Voluntary IBI increases were associated with significant increases in TWVM and RSA, and voluntary IBI decreases were associated with significant reductions in RSA and nonsignificant reductions in TWVM. This pattern of results suggests that alterations in cardiac vagal tone are involved in voluntary IBI increases and decrease tasks. The results also suggest a role for cardiac sympathetic nervous activity in voluntary IBI increase. The role of changing respiration cycle period was also investigated.This research was supported in part by a Department of Psychiatry Medical Student Research Stipend to Courtney German. The design and construction of the biofeedback apparatus used in this research fulfilled in part the requirements for a Master of Science degree in engineering from St. Mary's University by Steve Borcherding.     

Spectral EEG characteristics in students with different anxiety profile during tests

EEG spectral power was calculated in 39 students at the age of 19-21 years in two experimental conditions: during the common educational process and immediately before an examination (stress condition). During the education process, in subjects with high anxiety (tested by Spielberger) the relative spectral power of the delta activity was higher than in the other group in the occipital, parietal, central, and right frontal brain areas, whereas the power of the EEG alpha in these areas was lower. Before examination tests, in subjects with high activity the delta power bilaterally increased in the temporal areas, whereas in subjects with low anxiety there was a decrease in the alpha rhythm power, especially in the right frontal area. In stress condition, the relative power of the delta activity in both occipital and temporal, right parietal and central areas was higher in subjects with low anxiety, whereas their alpha power was lower in both frontal and in occipital, parietal, and temporal areas of the left hemisphere.