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.     

Effects of repeated exercise/rest sessions at –10°C on skin and rectal temperatures in men wearing chemical protective clothing

The development of thermophysiological responses during four consecutive exercise/rest sessions in the cold was studied in men wearing chemical protective clothing and a face mask. Six men repeated four exercise/rest sessions during 8 h at –10°C. Each session consisted of step exercise (240 W · m⁻²) for 60 min and rest for another 60 min. Rectal and skin temperatures were measured continuously and thermal sensations were obtained at 30-min intervals. Entering the cold from a warm environment and the onset of exercise resulted in a decrease in skin temperatures during the first session and the decrement in the temperatures of the extremities continued for 10–20 min during the following period of exercise. Torso skin temperature was at its lowest during the first rest period. After the first session of cold exposure the range and the level of variation in mean body temperature (Tˉ _b) followed a pattern which was repeated until the end of the experiment. However, the torso skin temperatures increased gradually until the fourth session, while the temperatures of the extremities, in contrast, tended to decrease up to the third session. In conclusion, the present results indicated that although Tˉ _b, reflecting the whole body heat balance, showed a typical pattern of change after the first session (2 h), the torso area was warming until the end of the cold exposure while the extremities continued to cool down up to the third session (6 h), obviously due to a prolonged redistribution of the circulation. Accepted: 29 May 1998     

Effectiveness of EMG biofeedback training for controlling arousal in subsequent stressful situations

Thirty-five subjects participated in (1) a pretreatment session during which arousal was measured while subjects anticipated and then viewed a stressful film; (2) four 20-min treatment sessions during which subjects received either contingent EMG biofeedback (biofeedback treatment), instructions to attend to a variable pitch tone (attention-placebo control), instructions to relax as much as possible (instructions-only control), or instructions to sit quietly (no-treatment control); and (3) a posttreatment session that was identical to the pretreatment session. Results indicate that when compared to the subjects in the control conditions, subjects who received EMG biofeedback were not effective in reducing frontalis EMG levels during treatment or while viewing the stressful film, but they were effective in reducing frontalis EMG levels while anticipating the stressful film. There was no evidence that EMG biofeedback influenced either skin conductance or self-reports of arousal.This research was supported in part by Bio-Medical and General Research Fund grants from the University of Kansas to David S. Holmes. Appreciation is due to B. Kent Houston, Edward F. Morrow, and Charles A. Hallenbeck for their contributions to the project.     

Treatment of phantom limb pain with combined EMG and thermal biofeedback: a case report

Phantom pain is a frequent consequence of the amputation of an extremity and causes considerable discomfort and disruption of daily activities. This study describes a patient with extreme phantom limb pain following amputation of the right upper limb. The treatment consisted of 6 sessions of EMG biofeedback followed by 6 sessions of temperature biofeedback. The patient did not use a prosthesis and had not received previous treatment for chronic pain. Results demonstrated complete elimination of phantom limb pain after treatment, which was maintained at a 3- and 12-month follow-up. Pain relief covaried with increase in skin temperature at stump and perceptual telescoping (retraction of phantom limb into stump).     

Respiratory Sinus Arrhythmia Versus Neck/Trapezius EMG and Incentive Inspirometry Biofeedback for Asthma: A Pilot Study

This pilot study compared biofeedback to increase respiratory sinus arrhythmia (RSA) with EMG and incentive inspirometry biofeedback in asthmatic adults. A three-group design (Waiting List Control n = 5, RSA biofeedback n = 6, and EMG biofeedback n = 6) was used. Six sessions of training were given in each of the biofeedback groups. In each of three testing sessions, five min. of respiratory resistance and EKG were obtained before and after a 20-min biofeedback session. Additional five-min epochs of data were collected at the beginning and end of the biofeedback period (or, in the control group, self-relaxation). Decreases in respiratory impedance occurred only in the RSA biofeedback group. Traub-Hering-Mayer (THM) waves (.03-.12 Hz) in heart period increased significantly in amplitude during RSA biofeedback. Subjects did not report significantly more relaxation during EMG or RSA biofeedback than during the control condition. However, decreases in pulmonary impedance, across groups, were associated with increases in relaxation. The results are consistent with Vaschillo's theory that RSA biofeedback exercises homeostatic autonomic reflex mechanisms through increasing the amplitude of cardiac oscillations. However, deep breathing during RSA biofeedback is a possible alternate explanation.     

The Use of Thermal Biofeedback in the Treatment of Pain Associated with Endometriosis: Preliminary Findings

Endometriosis is a common gynecological disease that causes marked physical and emotional distress in lives of women, resulting in dysmenorrhea, pain, or both throughout the menstrual cycle in over 96% of cases. A multiple case study design (N = 5) was employed to investigate the use of thermal biofeedback in the treatment of pain associated with endometriosis. The majority of participants (4 out of 5) were able to demonstrate mastery over hand temperature through thermal biofeedback. Of those participants, significant reductions in various aspects of pain were observed by the end of the study; one had a significant increase in Life Control; two had reductions in Pain Severity; three had a decrease in Affective Distress; and all 4 demonstrated reduction in Life Interference, as measured by the West Haven-Yale Multidimensional Pain Inventory. This is a preliminary study with a small sample size and without a control sample; hence, the results are considered only as suggestive of the potential use of biofeedback therapy in alleviating pain and associated symptomatology related to endometriosis. Further research is warranted.     

Subjective experiences associated with thermal biofeedback treatment of hypertension

Reports of subjective experiences of 73 hypertensive patients who were treated with thermal biofeedback for hand warming were obtained over 16 treatment sessions. Most of the differential responding in subjective report occurred in the first 5 sessions. Differences in reports of throbbing were associated with medication status during treatment (presence of sympatholytic antihypertensive agent). From 4 to 9% of patients report negative subjective experiences at any one session. When short-term clinical successes (either elimination of medication or reduction of BP) were compared with short-term failures, it was found that successes reported more warmth, more likelihood of falling asleep, and more dreamlike experiences. The latter were more likely to occur suddenly for the successes. Correlational analyses revealed consistent positive associations between reports of warmth and relaxation with highest temperature achieved in the session and consistent negative associations between experiencing physical sensations and degree of temperature change within the session.     

Physiological mechanism of digital vasoconstriction training

Recent work in our laboratory has shown that vasodilation produced during temperature biofeedback training is mediated through a nonneural, beta-adrenergic mechanism. Here we sought to determine if the effects of feedback training for vasoconstriction are produced through a neural or nonneural pathway and whether other measures of physiological activity are correlated with these changes. Nine normal subjects received temperature feedback vasoconstriction training in which feedback was delivered only during periods of successful performance. In a subsequent session, the nerves to one finger were blocked with a local anesthetic while finger blood flow was recorded from this and other fingers. Vasoconstriction occurred during feedback in the intact fingers but not in the nerve-blocked finger and was accompanied by increased skin conductance and heart rate. These data demonstrate that temperature feedback vasoconstriction training is mediated through an efferent, sympathetic nervous pathway. In contrast, temperature feedback vasodilation training is mediated through a nonneural, beta-adrenergic mechanism.     

Specificity of finger pulse volume feedback during relaxation

The effect of biofeedback during brief periods of relaxation was examined. Two groups (10 subjects in each group) were asked to relax as completely as possible during a series of six 3-minute relaxation periods in each of two 1-hr sessions. One group received biofeedback based on finger pulse volume (FPV) during the relaxation trials, while the other group received no biofeedback. Measures of heart rate, respiration rate, skin conductance level, and FPV were recorded during the sessions, and subjective ratings concerning relaxation were obtained after each session. The results showed that FPV scores for the groups differed during the relaxation trials of the second session, but other measures failed to distinguish between the groups. The group that received FPV feedback revealed a significantly higher level of FPV (relative to baseline) than the group that received no feedback.     

Muscular response to the therapist and symptomatic improvement during biofeedback for tension headache.

The relationship between muscular response to the therapist's presence and symptomatic improvement was studied during biofeedback. Thirty-two patients suffering from tension headaches received muscular biofeedback training of six sessions plus a follow-up session two months later. Patients' electro-myographic frontal response was measured prior to treatment both with and without the therapist present. A relationship was found between symptomatic improvement at follow-up and muscular response to the therapist's presence before treatment: patients showing a decrease of at least 10% in muscular tension response to the presence of their future therapist improved more regarding headache intensity than the patients showing increase or smaller variation of their EMG. A significant correlation of .59 was found between the frontal EMG response to therapist presence during the evaluation session and headache improvement at follow-up. The results suggest that the decrease of muscular tension during the first contact with the therapist could be an indicator of good prognosis, possibly because of an immediate positive therapeutic relationship and/or favorable expectancies concerning future benefit of treatment.     

Subjective experiences associated with thermal biofeedback treatment of hypertension

Reports of subjective experiences of 73 hypertensive patients who were treated with thermal biofeedback for hand warming were obtained over 16 treatment sessions. Most of the differential responding in subjective report occurred in the first 5 sessions. Differences in reports of throbbing were associated with medication status during treatment (presence of sympatholytic antihypertensive agent). From 4 to 9% of patients report negative subjective experiences at any one session. When short-term clinical successes (either elimination of medication or reduction of BP) were compared with short-term failures, it was found that successes reported more warmth, more likelihood of falling asleep, and more dreamlike experiences. The latter were more likely to occur suddenly for the successes. Correlational analyses revealed consistent positive associations between reports of warmth and relaxation with highest temperature achieved in the session and consistent negative associations between experiencing physical sensations and degree of temperature change within the session.This research was supported in part by grants from NHLBI, HL-27622 and HL-31189.     

Actual temperature during and thermal response after whole-body cryotherapy in cryo-cabin

Whole-body cryotherapy (WBC) involves exposing minimally dressed participants to very cold air (injecting liquid nitrogen with temperature −195 °C), either in a specially designed chamber (cryo-chamber) or cabin (cryo-cabin), for a short period of time. The aim of this study was to examine the actual temperature of the air in the cryo-cabin at different locations throughout the cabin by using human subjects and a manikin. Additionally, we monitored skin temperature before and for 60 min after the cryo-cabin session. Twelve subjects completed one 3 min cryo-cabin session. Temperature next to the skin was assessed during the session, while the skin temperature was monitored before, 3 min after and every 10 min for 60 min after completing the session. There was a statistically significant interaction (time×position) for temperature among the different body parts during the WBC, and for skin temperature among different body parts after the cryo-cabin session. Statistically significant time effects during and following cryo-cabin session were present for all body parts. We showed that actual temperature in the cryo-cabin is substantially different from the one reported by the manufacturer. Thermal response after cryo-cabin session is similar to response observed after cryo-chamber cold exposure reported in previously published studies. This could be of great practical value as cryo-cabins are less expensive and easier to use compared to cryo-chambers.     

Muscular response to the therapist and symptomatic improvement during biofeedback for tension headache

The relationship between muscular response to the therapist's presence and symptomatic improvement was studied during biofeedback. Thirty-two patients suffering from tension headaches received muscular biofeedback training of six sessions plus a follow-up session two months later. Patients' electro-myographic frontal response was measured prior to treatment both with and without the therapist present. A relationship was found between symptomatic improvement at follow-up and muscular response to the therapist's presence before treatment: patients showing a decrease of at least 10% in muscular tension response to the presence of their future therapist improved more regarding headache intensity than the patients showing increase or smaller variation of their EMG. A significant correlation of .59 was found between the frontal EMG response to therapist presence during the evaluation session and headache improvement at follow-up. The results suggest that the decrease of muscular tension during the first contact with the therapist could be an indicator of good prognosis, possibly because of an immediate positive therapeutic relationship and/or favorable expectancies concerning future benefit of treatment.The authors thank Mrs. G. Parisé for her assistance during the experimentation, Ms. M. Newman for her editorial corrections, and Ms. A. Khan for her secretarial work.     

Rehabilitation of an electrical burn patient through thermal biofeedback

A 22-year-old male subject, with high-voltage electrical burns to one wrist, utilized differential relaxation and visual biofeedback to increase skin temperature in the damaged hand. Through 14 thermal biofeedback and passive relaxation sessions, the subject was able to produce temperature increases in his damaged hand of up to 21°F, which considerably diminished the pain. Healing, feeling, and movement control seemed to progress with extreme rapidity, suggesting that axoplasmic transport was greatly enhanced.The authors gratefully acknowledge the assistance of Dr. Ranjit Singh, M.B., FRCP (C).     

Exhaled Air Dispersion during Coughing with and without Wearing a Surgical or N95 Mask

Objectives

We compared the expelled air dispersion distances during coughing from a human patient simulator (HPS) lying at 45° with and without wearing a surgical mask or N95 mask in a negative pressure isolation room.

Methods

Airflow was marked with intrapulmonary smoke. Coughing bouts were generated by short bursts of oxygen flow at 650, 320, and 220L/min to simulate normal, mild and poor coughing efforts, respectively. The coughing jet was revealed by laser light-sheet and images were captured by high definition video. Smoke concentration in the plume was estimated from the light scattered by smoke particles. Significant exposure was arbitrarily defined where there was ≥ 20% of normalized smoke concentration.

Results

During normal cough, expelled air dispersion distances were 68, 30 and 15 cm along the median sagittal plane when the HPS wore no mask, a surgical mask and a N95 mask, respectively. In moderate lung injury, the corresponding air dispersion distances for mild coughing efforts were reduced to 55, 27 and 14 cm, respectively, p < 0.001. The distances were reduced to 30, 24 and 12 cm, respectively during poor coughing effort as in severe lung injury. Lateral dispersion distances during normal cough were 0, 28 and 15 cm when the HPS wore no mask, a surgical mask and a N95 mask, respectively.

Conclusions

Normal cough produced a turbulent jet about 0.7 m towards the end of the bed from the recumbent subject. N95 mask was more effective than surgical mask in preventing expelled air leakage during coughing but there was still significant sideway leakage.     

EMG biofeedback for functional bladder-sphincter dyssynergia: A case study

The present study utilized EMG biofeedback in the treatment of functional bladder-sphincter dyssynergia, a learned incoordination of bladder and urethral sphincter activity during voiding. The condition is usually associated with a history of painful urination due to bladder infections, surgery, or harsh toilet training. The subject was an 8-year-old girl with chronic diurnal urinary frequency, urge incontinence, and nocturnal enuresis. Treatment consisted of intensive instruction in alternately tensing and relaxing her lower pelvic musculature, as well as relaxing during voiding. These exercises were accompanied by EMG biofeedback from perianal and perivaginal surface electrode sites. Home practice consisted of the tense-relax exercise, relaxation during voiding, and self-monitoring and record-keeping. There were 17 sessions over a period of 9 months. No medication was used. Marked reduction (to normal levels) in diurnal urgency and frequency occurred by the 3rd week of therapy, and complete recovery of normal function, including nocturnal continence without waking, occurred by the 13th therapy session, 5 months after therapy began. Follow-up 1 year after therapy revealed that these gains were being maintained. Pre- and posttherapy urodynamic studies corroborated the achievement of normal urinary function.     

Comparisons of high, medium, and low feedback sensitivity for the control of heart-rate acceleration

Thirty-four student volunteers were randomly assigned to one of three feedback sensitivity conditions: high sensitivity, medium sensitivity, or low sensitivity. Each subject received four sessions of biofeedback training with instructions to accelerate heart rate. In each condition, analogue feedback was provided during heart-rate acceleration trials. In addition to heart rate, frontal EMG and digital skin temperature were also recorded. Results replicated and extended the findings of a previous study in that medium and low sensitivity feedback was found to be superior to high sensitivity feedback during the final training session. These results confirm previous findings that a high sensitivity feedback produces very poor control of heart-rate acceleration. These data were discussed in terms of motor skills theory and in terms of possible effects of feedback sensitivity upon the motivation of subjects.     

Rehabilitation of an electrical burn patient through thermal biofeedback

A 22-year-old male subject, with high-voltage electrical burns to one wrist, utilized differential relaxation and visual biofeedback to increase skin temperature in the damaged hand. Through 14 thermal biofeedback and passive relaxation sessions, the subject was able to produce temperature increases in his damaged hand of up to 21 degrees F, which considerably diminished the pain. Healing, feeling, and movement control seemed to progress with extreme rapidity, suggesting that axoplasmic transport was greatly enhanced.     

Reliability of Infrared Plethysmography in BVP Biofeedback Therapy and the Relevance for Clinical Application

Biofeedback methods are well established as behavioral techniques for the therapy of various psychophysiological diseases. The forms of feedback generally employed are muscle activity (electromyogram), skin temperature, brain activity (electroencephalogram), and vasomotoricity. The latter technique, which employs plethysmographic feedback, has been studied most extensively in the therapy of migraine (vasoconstriction training, blood volume pulse training). Although the clinical efficacy has been demonstrated in several studies, little is known about the psychometric properties of this technique. This study examined the intrasession and intersession reliability of the pulse volume amplitude (PVA). The results showed that the PVA measurements within a single biofeedback session were highly reliable. Repositioning of the probe within the session resulted in a lower correlation coefficient, but one that was still sizable and significant. The PVA values from different sessions were not reliable (or comparable).