Effects of inhaled nicotine on instrumental learning of blood pressure responses.

The present study investigated the effects of biofeedback of arterial blood pressure on cortical, peripheral, and psychological measures and the dependence of these effects on nicotine. Four groups of subjects, nonsmokers, and habitual smokers who smoked cigarettes during the experimental sessions containing 0.3, 0.8, or 1.5 mg nicotine, respectively, participated in a feedback paradigm in which continuous feedback of mean blood pressure was provided for intervals of 8 s each. While tonic blood pressure did not differ between the groups, the ability to modulate blood pressure (under feedback conditions) was restricted in smokers as compared to nonsmoking subjects; increasing nicotine dosage was accompanied by poorer performance. Independently of habitual smoking and nicotine doses, heart rate increased during feedback and under conditions of blood pressure increase. In smokers, activity in the alpha band was reduced in a dose-dependent manner. Slow cortical potentials (SCPs) during the feedback interval varied with self-induced blood pressure changes in nonsmokers (blood pressure increase was accompanied by reduced surface-negative potential shifts and vice versa), while SCP variations during feedback conditions were small in smokers, more so under the influence of 0.3 and 0.8-mg nicotine, less so under 1.5 mg. Verbal reports suggest that awareness of performance strategies may not be a necessary variable for performance on the blood pressure regulation task.     

Effects of inhaled nicotine on instrumental learning of blood pressure responses

The present study investigated the effects of biofeedback of arterial blood pressure on cortical, peripheral, and psychological measures and the dependence of these effects on nicotine. Four groups of subjects, nonsmokers, and habitual smokers who smoked cigarettes during the experimental sessions containing 0.3, 0.8, or 1.5 mg nicotine, respectively, participated in a feedback paradigm in which continuous feedback of mean blood pressure was provided for intervals of 8 s each. While tonic blood pressure did not differ between the groups, the ability to modulate blood pressure (under feedback conditions) was restricted in smokers as compared to nonsmoking subjects; increasing nicotine dosage was accompanied by poorer performance. Independently of habitual smoking and nicotine doses, heart rate increased during feedback and under conditions of blood pressure increase. In smokers, activity in the alpha band was reduced in a dose-dependent manner. Slow cortical potentials (SCPs) during the feedback interval varied with self-induced blood pressure changes in nonsmokers (blood pressure increase was accompanied by reduced surface-negative potential shifts and vice versa), while SCP variations during feedback conditions were small in smokers, more so under the influence of 0.3 and 0.8-mg nicotine, less so under 1.5 mg. Verbal reports suggest that awareness of performance strategies may not be a necessary variable for performance on the blood pressure regulation task.This experiment was supported by Reemtsma Inc. Hamburg, which also provided the experimental cigarettes.     

Heart rate variability biofeedback as a method for assessing baroreflex function: a preliminary study of resonance in the cardiovascular system

This study describes the use of a biofeedback method for the noninvasive study of baroreflex mechanisms. Five previously untrained healthy male participants learned to control oscillations in heart rate using biofeedback training to modify their heart rate variability at specific frequencies. They were instructed to match computer-generated sinusoidal oscillations with oscillations in heart rate at seven frequencies within the range of 0.01–0.14 Hz. All participants successfully produced high-amplitude target-frequency oscillations in both heart rate and blood pressure. Stable and predictable transfer functions between heart rate and blood pressure were obtained in all participants. The highest oscillation amplitudes were produced in the range of 0.055–0.11 Hz for heart rate and 0.02–0.055 Hz for blood pressure. Transfer functions were calculated among sinusoidal oscillations in the target stimuli, heart rate, blood pressure, and respiration for frequencies at which subjects received training. High and low target-frequency oscillation amplitudes at specific frequencies could be explained by resonance among various oscillatory processes in the cardiovascular system. The exact resonant frequencies differed among individuals. Changes in heart rate oscillations could not be completely explained by changes in breathing. The biofeedback method also allowed us to quantity characteristics of inertia, delay, and speed sensitivity in baroreflex system. We discuss the implications of these findings for using heart rate variability biofeedback as an aid in diagnosing various autonomic and cardiovascular system disorders and as a method for treating these disorders.     

Should we tell them when their blood pressure is up?

We carried out two studies to determine the effects of feedback on subsequent blood pressure and heart rate readings in subjects without significant cardiovascular abnormalities. In both studies the subjects were randomly assigned to be told that their blood pressure was normal or was high or to receive no feedback at all; 3 minutes later another reading was taken and correct feedback provided. Study 1 was done in 114 patients who attended a family practice teaching unit for an office visit; subjects taking cardioactive medication or with chronically elevated blood pressure (diastolic pressure more than 95 mm Hg) or known low pressure (diastolic pressure less than 60 mm Hg) were excluded. Half of the subjects received feedback from a nurse and the other half from a physician. We found no effect of type of feedback or type of practitioner on subsequent readings. No adaptation of diastolic blood pressure or heart rate took place, whereas a similar rest period in the laboratory consistently triggers cardiovascular adaptation. Given the field nature of the study it was not clear whether the intervention was not powerful or whether the practitioner-patient interactions diffused the effects of an otherwise powerful intervention. Therefore, a second study with the same design was carried out in a controlled laboratory setting with 61 university students who believed they were in the adaptation phase of an experimental stress protocol. The subjects did not interact with the experimenter, who provided only the initial feedback, via intercom. The findings replicated those of study 1: type of feedback had no significant effect on subsequent blood pressure levels, and all types of feedback prevented cardiovascular adaptation. We recommend that patients be allowed to rest alone for at least 10 minutes before blood pressure is measured. Our findings suggest that practitioners need not be concerned about telling normotensive or borderline hypertensive patients that their blood pressure is elevated.     

Heart rate biofeedback and cold pressor pain: effects of expectancy

The study investigated the effects of expectancy on the reduction of cold pressor test pain using heart rate biofeedback training. Thirty-six male subjects were given an initial 45-sec cold pressor test, 25 heart rate decrease feedback training trials, and a final cold pressor test in which they were told to decrease their heart rate, but without the aid of feedback. Two levels of outcome expectancy (increase pain, decrease pain) and two levels of cold pressor water temperature (0 degrees C, 5 degrees C), resulting in four groups (N = 9 per group), were used to assess the interaction between expectancy and aversive stimulus intensity. Immediately prior to the final cold pressor test, the increase pain expectancy subjects were told that decreasing their heart rate during the ice water immersion would cause more pain. Decrease pain subjects were told that decreasing their heart rate would cause less pain. Expectancy was found to be the major determinant of pain reports. The decrease pain subjects consistently reported less pain on the final cold pressor, whereas the increase pain subjects consistently reported more pain. Contrary to prediction, expectancy effects were greater for the colder water. The findings indicate the importance of expectancy in the clinical use of biofeedback to control pain.     

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.     

Characteristics of Resonance in Heart Rate Variability Stimulated by Biofeedback

As we previously reported, resonant frequency heart rate variability biofeedback increases baroreflex gain and peak expiratory flow in healthy individuals and has positive effects in treatment of asthma patients. Biofeedback readily produces large oscillations in heart rate, blood pressure, vascular tone, and pulse amplitude via paced breathing at the specific natural resonant frequency of the cardiovascular system for each individual. This paper describes how resonance properties of the cardiovascular system mediate the effects of heart rate variability biofeedback. There is evidence that resonant oscillations can train autonomic reflexes to provide therapeutic effect. The paper is based on studies described in previous papers. Here, we discuss the origin of the resonance phenomenon, describe our procedure for determining an individual's resonant frequency, and report data from 32 adult asthma patients and 24 healthy adult subjects, showing a negative relationship between resonant frequency and height, and a lower resonant frequency in men than women, but no relationship between resonant frequency and age, weight, or presence of asthma. Resonant frequency remains constant across 10 sessions of biofeedback training. It appears to be related to blood volume.     

Heart rate biofeedback and cold pressor pain: Effects of expectancy

The study investigated the effects of expectancy on the reduction of cold pressor test pain using heart rate biofeedback training. Thirty-six male subjects were given an initial 45-sec cold pressor test, 25 heart rate decrease feedback training trials, and a final cold pressor test in which they were told to decrease their heart rate, but without the aid of feedback. Two levels of outcome expectancy (increase pain, decrease pain) and two levels of cold pressor water temperature (0°C, 5°C), resulting in four groups (N=9 per group), were used to assess the interaction between expectancy and aversive stimulus intensity. Immediately prior to the final cold pressor test, the increase pain expectancy subjects were told that decreasing their heart rate during the ice water immersion would cause more pain. Decrease pain subjects were told that decreasing their heart rate would cause less pain. Expectancy was found to be the major determinant of pain reports. The decrease pain subjects consistently reported less pain on the final cold pressor, whereas the increase pain subjects consistently reported more pain. Contrary to prediction, expectancy effects were greater for the colder water. The findings indicate the importance of expectancy in the clinical use of biofeedback to control pain.This research was supported by National Institute of Mental Health Research Grant MH-26923. Computing assistance was provided by the Office of Academic Computing, UCLA. We would like to thank Lisa Greenstadt, John Richards, John Reeves, and Barbara Smith for their assistance.     

Learned Cardiac Control with Heart Rate Biofeedback Transfers to Emotional Reactions

Emotions involve subjective feelings, action tendencies and physiological reactions. Earlier findings suggest that biofeedback might provide a way to regulate the physiological components of emotions. The present study investigates if learned heart rate regulation with biofeedback transfers to emotional situations without biofeedback. First, participants learned to decrease heart rate using biofeedback. Then, inter-individual differences in the acquired skill predicted how well they could decrease heart rate reactivity when later exposed to negative arousing pictures without biofeedback. These findings suggest that (i) short lasting biofeedback training improves heart rate regulation and (ii) the learned ability transfers to emotion challenging situations without biofeedback. Thus, heart rate biofeedback training may enable regulation of bodily aspects of emotion also when feedback is not available.     

The comparative effectiveness of heart rate biofeedback,speech skills training,and a combination of both in treating public-speaking anxiety

Forty-two speech-anxious undergraduate students (21 female, 21 male) were administered either heart rate biofeedback training, speech skills training, or a combination of both to aid in the alleviation of speech anxiety. Physiological (heart rate, tonic skin conductance level, systolic blood pressure, and diastolic blood pressure), overt motor, and self-report measures of anxiety were assessed during a pretreatment speech and two posttreatment speeches. Results indicated that all treatments were effective in lowering overt motor and self-report components of anxiety. However, only the biofeedback and combined group subjects demonstrated significantly less heart rate increase while speaking before an audience during the posttreatment assessment. Two individual difference variables examined in this study — cognitive/autonomic focus of anxiety and subjective confidence in treatment — were not found to significantly influence treatment effectiveness. Finally, factor analyses of the physiological data suggested that heart rate changes play a large role in the physiological component of anxiety.     

Biofeedback heart rate training during exercise

Eighteen healthy human subjects participated in weekly sessions of five 10-minute trials of walking on a treadmill at 2.5 mph and 6% grade. Eight experimental subjects received beat-to-beat heart rate biofeedback during the exercise and were instructed to try to lower their heart rates; ten control subjects did not receive feedback. By the end of 5 weeks (25 trials), the experimental group showed a significantly lower mean heart rate (96.8 vs. 108.6 bpm), systolic blood pressure (114.0 vs. 131.3 mmHg), and rate-pressure product (11.0×10³ vs. 14.3×10³ bpm-mmHg) during exercise than the control group. These differences were maintained after crossover of the feedback provision for five more weeks.     

An integrated blood volume pulse biofeedback system for migraine treatment

A blood volume pulse (BVP) biofeedback system is described that integrates BVP amplitude to provide a signal appropriate for auditory feedback. In comparison to binary BVP feedback methods, this integrated system offers the advantages of continuous feedback and increased scoring ease. The validity of this system was established by correlating the integrated BVP output with trough-to-peak measurements of the raw BVP signal during unassisted relaxation and temporal BVP biofeedback with eight migraine headache patients. Within-subject correlations of the integrated and raw BVP outputs ranged from .82 to .98 (X=.95). Although the integrated method admits unwanted BVP changes in rate, correlation analyses showed this confound factor to be small. Increments in biofeedback training effects were observed during the treatment course. Substantive migraine relief was achieved by the end of treatment and therapeutic gains were maintained at 1-year follow-up. In conclusion, it appears that this method successfully presents continuous auditory feedback from an integrated BVP signal resulting in therapeutic benefits to migraineurs.     

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.     

Arousal reduction with biofeedback-supported respiratory meditation

This study investigated the effectiveness of a relaxation procedure that combines a concentration aid, in the form of biofeedback, with elements of approved relaxation procedures. Ten subjects completed two sessions, one with and one without feedback. Half of the subjects started with the feedback session and then completed the session without feedback; the other half had the reverse order. In the experimental procedure, subjects had to concentrate on their exhalation, being supported by respiratory feedback. In the background they heard slow movements of baroque music and relaxation-suggesting sentences. The control procedure contained only background music and relaxation-suggesting sentences. Both procedures elicited a trophotropic response: Finger temperature increased while skin conductance level, number of skin conductance responses, and muscle tension decreased. However, with respiratory feedback and meditation, there was an additional, specific effect, a decrease in respiration and heart rate, to an extent not found in the control procedure. It is suggested that exhalation feedback helps to concentrate on the exhalation process and by this means slows respiration rate, and as a consequence, also heart rate. Therefore, respiratory feedback could be a useful tool for inducing relaxation and slowing of heart rate.The author would like to thank Carlo Thomas for his assistance in the data analysis of the experiment described in the article.     

A Pilot Study of the Efficacy of Heart Rate Variability (HRV) Biofeedback in Patients with Fibromyalgia

Fibromyalgia (FM) is a non-inflammatory rheumatologic disorder characterized by musculoskeletal pain, fatigue, depression, cognitive dysfunction and sleep disturbance. Research suggests that autonomic dysfunction may account for some of the symptomatology of FM. An open label trial of biofeedback training was conducted to manipulate suboptimal heart rate variability (HRV), a key marker of autonomic dysfunction. Methods: Twelve women ages 18–60 with FM completed 10 weekly sessions of HRV biofeedback. They were taught to breathe at their resonant frequency (RF) and asked to practice twice daily. At sessions 1, 10 and 3-month follow-up, physiological and questionnaire data were collected. Results: There were clinically significant decreases in depression and pain and improvement in functioning from Session 1 to a 3-month follow-up. For depression, the improvement occurred by Session 10. HRV and blood pressure variability (BPV) increased during biofeedback tasks. HRV increased from Sessions 1–10, while BPV decreased from Session 1 to the 3 month follow-up. Conclusions: These data suggest that HRV biofeedback may be a useful treatment for FM, perhaps mediated by autonomic changes. While HRV effects were immediate, blood pressure, baroreflex, and therapeutic effects were delayed. This is consistent with data on the relationship among stress, HPA axis activity, and brain function.     

The role of behavioral conditioning in the cardiovascular adjustment to exercise

The purpose of this study was to determine if normal subjects could be trained to attenuate their cardiovascular responses while exercising on a bicycle ergometer. Ten young, untrained subjects exercised on a bicycle ergometer for five sessions. Half of the group was asked to slow their heart rate while exercising with heart rate feedback during exercise. Their average heart rate increase was 20% less than that of the control subjects, who exercised without feedback. The control subjects subsequently also received feedback during exercise and they were able to attenuate their heart rate responses comparably. Systolic blood pressure was not affected by feedback training. Changes in rate-pressure product paralleled changes in heart rate. These data show that autonomically mediated adjustments to exercise can be brought under experimental control through the use of appropriate behavioral techniques.     

Effectiveness of multiple muscle-site EMG biofeedback and relaxation training in reducing the aversiveness of cancer chemotherapy

A 44-year-old female cancer patient was given progressive muscle relaxation training and multiple muscle-site EMG biofeedback to reduce the conditioned negative responses she had apparently developed to her chemotherapy treatments. Following three baseline chemotherapy sessions, the patient was given relaxation training and biofeedback during four consecutive chemotherapy treatments and was asked to practice her relaxation skills daily in the hospital or at home. After the patient felt able to relax on her own, relaxation training and biofeedback were terminated and three follow-up sessions were held. Results indicated that during the chemotherapy sessions in which the patient received relaxation training and biofeedback, she showed reductions in physiological arousal (EMG, pulse rate, systolic blood pressure, and diastolic blood pressure) and reported feeling less anxious and nauseated. Moreover, these changes were maintained during the follow-up sessions. These results suggest that relaxation training plus multiple muscle-site biofeedback may be an effective adjunctive procedure for reducing some of the adverse side effects of cancer chemotherapy.     

Reduction of blood pressure by indirect biofeedback

Forty-five randomly assigned subjects served in either a relaxation control, an EMG plus thermal, or a thermal biofeedback group. All groups received the same relaxation manipulation. Experimental results demonstrated a significant drop in both diastolic and systolic blood pressure for the feedback treatment. Diastolic measures showed a somewhat greater decrease for the EMG plus thermal treatment condition. A learning effect was demonstrated both within and across the three experimental sessions. Given that the sample was normotensive, the 20% reduction in blood pressure was notable. The results support the idea that blood pressure biofeedback is not a necessary condition for reduction of arterial blood pressure.     

Heart-rate reactivity to cold pressor stress following biofeedback training

Three previous studies have shown that biofeedback training is useful in modifying heart-rate and pain ratings during ice water stimulation (cold pressor test). Subjects were given an initial cold pressor followed by heart-rate biofeedback training and a final cold pressor test in which they were instructed to control their heart rate in accordance with the prior training. It was assumed that a heart-rate control skill had been learned. In the present study, two groups of subjects (N = 9 each) were given either increase or decrease heart-rate biofeedback training following the same procedures as previously, but subjects were not instructed to control their heart rate during the final cold pressor test. Heart rate, skin conductance, electromyographic activity, and respiration were measured. The biofeedback training effects replicate the previous results. However, no heart-rate or pain rating differences were found between the two groups during the final cold pressor test. Thus, previous findings cannot be accounted for simply by a shift in heart rate and/or pain reactivity following training itself. The findings suggest that a biofeedback strategy may be useful in modifying physiological and subjective responses to painful stimuli but only if it can be used as an active coping skill.     

The effects of EMG feedback training during problem solving: a case study.

The present case study investigated the effects of competing task demands on biofeedback training to reduce frontalis muscle tension. Baseline levels of frontalis muscle tension were recorded for relaxation and problem solving. The subject was trained to decrease muscle tension with biofeedback for the problem-solving task alone. The results indicated that EMG training during problem-solving was successfully accomplished. Frontalis muscle tension during relaxation baseline did not change as a result of reductions in muscle tension during problem-solving feedback training. This suggests that the decrease of muscle tension cannot be attributed to reductions in overall muscle tension levels. Instead, training was specific to the problem-solving feedback phases. Additionally, it was found that accuracy in problem-solving did not decline as a result of simultaneous feedback training. Thus EMG biofeedback training can be accomplished and exercised without disruption of ongoing mental activity.