Sequence effects of relaxation training, EMG, and temperature biofeedback on anxiety, symptom report, and self-concept

Bispectral Index Alterations and Associations With Autonomic Changes During Hypnosis in Trauma Center Researchers: Formative Evaluation Study

BACKGROUND

Previous work performed by our group demonstrated that intermittent reductions in bispectral index (BIS) values were found during neurofeedback following mindfulness instructions. Hypnosis was induced to enhance reductions in BIS values.

OBJECTIVE

This study aims to assess physiologic relaxation and explore its associations with BIS values using autonomic monitoring.

METHODS

Each session consisted of reading a 4-minute baseline neutral script and playing an 18-minute hypnosis tape to 3 researchers involved in the BIS neurofeedback study. In addition to BIS monitoring, autonomic monitoring was performed, and this included measures of electromyography (EMG), skin temperature, skin conductance, respiratory rate, expired carbon dioxide, and heart rate variability. The resulting data were analyzed using two-tailed t tests, correlation analyses, and multivariate linear regression analyses.

RESULTS

We found that hypnosis was associated with reductions in BIS (P<.001), EMG (P<.001), respiratory rate (P<.001), skin conductance (P=.006), and very low frequency power (P=.04); it was also associated with increases in expired carbon dioxide (P<.001), skin temperature (P=.04), high frequency power (P<.001), and successive heart interbeat interval difference (P=.04) values. Decreased BIS values were associated with reduced EMG measures (R=0.76; P<.001), respiratory rate (R=0.35; P=.004), skin conductance (R=0.57; P<.001), and low frequency power (R=0.32; P=.01) and with increased high frequency power (R=-0.53; P<.001), successive heart interbeat interval difference (R=-0.32; P=.009), and heart interbeat interval SD (R=-0.26; P=.04) values.

CONCLUSIONS

Hypnosis appeared to induce mental and physical relaxation, enhance parasympathetic neural activation, and attenuate sympathetic nervous system activity, changes that were associated with BIS values. Findings from this preliminary formative evaluation suggest that the current hypnosis model may be useful for assessing autonomic physiological associations with changes in BIS values, thus motivating us to proceed with a larger investigation in trauma center nurses and physicians.

Temperature Biofeedback Training to Improve Peripheral Blood Flow in the Upper Extremities of Diabetic Patients

Ten control and ten diabetic subjects were first given a baseline session of no temperature biofeedback, and then were exposed to four 40-minute temperature biofeedback sessions over consecutive days. As the result of feedback training, peripheral skin temperatures increased on the training (right) hands of both groups, and this occurred to a greater extent in the diabetic group. Concomitant temperature increases occurred also in the left hands of both groups. Neither group produced any significant changes in heart rate, respiration rate, or systolic blood pressure with the exception of a significant decrease in diastolic blood pressure for the diabetic group. No difference in diastolic blood pressure was observed, however, when the diabetics were compared with the control group. The results would suggest further evaluation of temperature biofeedback training is warranted in a diabetic population as a potential means of increasing peripheral blood flow in the extremities.

Biofeedback for psychiatric disorders: a systematic review

Biofeedback potentially provides non-invasive, effective psychophysiological interventions for psychiatric disorders. The encompassing purpose of this review was to establish how biofeedback interventions have been used to treat select psychiatric disorders [anxiety, autistic spectrum disorders, depression, dissociation, eating disorders, schizophrenia and psychoses] to date and provide a useful reference for consultation by clinicians and researchers planning to administer a biofeedback treatment. A systematic search of EMBASE, MEDLINE, PsycINFO, and WOK databases and hand searches in Applied Psychophysiology and Biofeedback, and Journal of Neurotherapy, identified 227 articles; 63 of which are included within this review. Electroencephalographic neurofeedback constituted the most investigated modality (31.7%). Anxiety disorders were the most commonly treated (68.3%). Multi-modal biofeedback appeared most effective in significantly ameliorating symptoms, suggesting that targeting more than one physiological modality for bio-regulation increases therapeutic efficacy. Overall, 80.9% of articles reported some level of clinical amelioration related to biofeedback exposure, 65.0% to a statistically significant (p < .05) level of symptom reduction based on reported standardized clinical parameters. Although the heterogeneity of the included studies warrants caution before explicit efficacy statements can be made. Further development of standardized controlled methodological protocols tailored for specific disorders and guidelines to generate comprehensive reports may contribute towards establishing the value of biofeedback interventions within mainstream psychiatry.

Peripheral temperature changes during rest and gender differences in thermal biofeedback

Thermal biofeedback (BFB) training is used extensively in clinical psychophysiology. However, there are large individual differences in the ability to control peripheral skin temperature and the magnitude of changes obtained varies considerably across studies. The aims of this study were: (1) to investigate the relationship between spontaneous peripheral temperature changes and changes voluntarily produced through a six-session thermal BFB training and (2) to investigate whether gender or other subjects' variables (trait anxiety, locus of control (LC) and field dependence) were related to learning of voluntary control of peripheral skin temperature. Results demonstrated that during the rest period preceding the feedback trials, there were consistent systematic temperature increases in which changes were bigger than those recorded in the BFB increase trials; among the subjects' variables considered, the only one that correlated significantly with learning ability was gender: Females showed greater control than males. Implications for clinical practice are discussed.

Variations in digital temperature during frontal EMG biofeedback training in normal subjects

During frontal EMG biofeedback training, the relationship between frontal EMG and digital skin temperature was investigated in two experiments, which varied the number of baseline and feedback sessions. The results of Experiment 1 suggested a "general relaxation effect," where digital temperature increased as frontal EMG decreased, especially for subjects with initially low hand temperature. Experiment 2 extended the number of baseline and feedback sessions and qualified the results of Experiment 1. EMG and digital temperature did not simultaneously converge toward general relaxation over the extended baseline or feedback sessions in Experiment 2. Furthermore, when the feedback signal was introduced, digital temperature dropped quickly but recovered to baseline levels within three feedback sessions; this drop in digital temperature was interpreted within the context of attentional demands of the biofeedback task. The results appeared consistent with the view that frontal biofeedback training teaches a discriminative skill of lower frontal EMG, and that this skill does not readily generalize to digital skin temperature.

Relaxation training affects success and activation on a teaching test

We studied the effects of an audiocassette-relaxation training period (ART) and its timing on success at a teaching test (lecture type), on observed tension and on a number of physiological responses. The electrical activity of the upper trapezius muscle (EMG), heart rate (HR) and blood pressure (BP), of female and male instructor candidates, were examined before, during and after the teaching test as well as during its critique. The relaxation period (18 min) was presented either on the preceding night (ARTnt) or immediately before the teaching test (ARTimm). The influence of personality (types A-B and extrovert-introvert) was also studied. ART improved success at the teaching test in both sexes. In males (but not in females), ARTimm decreased EMG level during the test, but ARTnt increased EMG at the test period as compared to the control group. In females, both ARTnt and ARTimm lowered HR more than in the control group. ARTimm lowered systolic BP in both sexes. Personality types affected the ART responses; ART was more beneficial for type A than B subjects.