Biofeedback Training of Blood Pressure: A Comparison of Three Feedback Techniques

Three biofeedback procedures were compared for their effectiveness in training subjects to modify systolic blood pressure (BP). Three groups of 6 normotensives received three training sessions using one of three types of systolic BP feedback: 1) proportional feedback at 75-sec intervals, 2) relatively continuous proportional feedback, or 3) a form of continuous binary feedback. Three subjects also completed a fourth, no-feedback, session. Each session consisted of 5 training cycles, during which the subject was first instructed to “lower” BP and then “don't lower” BP. This design permitted demonstration of subjects' ability to control BP, rather than just lowering it. Systolic and diastolic BPs were recorded, as were heart rate, respiration rate and respiration volume. The continuous binary feedback technique was most successful in producing systolic BP control, apparently due to the short feedback latency and maximal information available to subjects. Diastolic BP often increased within sessions even when systolic BP decreased. No consistent covariation between BP and other physiological responses was observed, although at times these responses varied systematically with instruction. Continued systolic BP control at diminished levels was demonstrated by subjects who completed a fourth, no-feedback, session.     

The Regulation of Blood Pressure Reactions to Taxing Conditions using Pulse Transit Time Feedback and Relaxation

Two experiments are described in which 40 normotensive subjects were trained to reduce blood pressure (BP) both in undistracting conditions and while performing taxing tasks. Biofeedback was compared with relaxation in each case, and BP was continously monitored by the pulse wave velocity method. In Study 1, feedback and relaxation groups produced similar BP reductions when control was attempted in isolation. However, the relaxation group was significantly disturbed during performance of an auditory choice reaction time (RT) task. In contrast, feedback subjects showed identical BP modifications in the two conditions. In Study 2, the differences during the RT task proved to be short lived. However, the feedback group overcame pressor reactions to a mental arithmetic test more rapidly than could relaxation subjects, and the difference between groups persisted during no-feedback trials. In both studies, modifications were more specific in the feedback condition, since alterations in heart rate, respiration and general activity were less prominent. It is suggested that it may be fruitful to use feedback for training people to overcome BP reactions to taxing conditions, rather than trying to modify tonic level alone.     

Operant Conditioning of Blood Pressure: Effects of Mediators

Respiration and frontalis muscle activity were evaluated as mediators in the operant conditioning of systolic blood pressure (BP). Three groups of 7 normotensives received 5 training sessions with either: a) systolic BP feedback alone, b) systolic BP feedback plus respiration rate and volume feedback, or c) systolic BP feedback plus frontalis muscle activity feedback. Respiration and muscle feedback subjects were given BP feedback so that they might test various response strategies for BP control. Each session consisted of 5 training cycles, during which the subject was instructed to “lower” BP and then “don't lower” BP. This design demonstrated subjects' BP control, while eliminating extraneous factors as sources of BP change. Respiration feedback clearly enhanced acquisition of BP control, while frontalis muscle feedback was ineffective as a BP mediator. Respiration subjects slowed respiration rate and increased respiration volume when lowering BP. No other systematic physiological changes occurred in any group. Reflex instigation of BP lowering in the respiration group was improbable for a variety of reasons. It was concluded that while mediators may not be essential for response acquisition, they can serve to enhance autonomic self-regulation. These findings have significant implications for hypertension treatment methodology.     

Binocular vision and the on-line control of human prehension

The contribution of binocular visual feedback to the kinematics of human prehension was studied in two related experiments. In both experiments, the field of view of each eye was independently controlled by means of goggles fitted with liquid-crystal shutters. While wearing these goggles, which permitted either a binocular or a monocular view of the world, subjects were required to reach out and grasp a target object, which varied in size and position from trial to trial. In experiment 1, two viewing conditions were used. In one condition, binocular vision was available throughout the entire trial; in the second condition, the initial binocular view was replaced by a monocular view after the reaching movement had been initiated. When only monocular feedback was available, subjects showed a prolonged deceleration phase, although the time they spent in contact with the object was the same in both conditions. In experiment 2, monocular vision was available throughout a given trial in one condition and was replaced by binocular vision upon movement initiation in the second condition. Subjects in this experiment also displayed a prolonged deceleration phase in the monocular feedback condition relative to their performance in the binocular feedback condition. Unlike experiment 1, however, allowing only monocular feedback resulted in an increase in the amount of time subjects spent in contact with the object. Moreover, the object contact phases under the two conditions of experiment 2 were much longer than those observed in experiment 1, in which subjects received initial binocular views of the object. This latter finding suggests that an initial binocular view provides better information about the size and location of the object-information that allows subjects to form their final grasp more efficiently. In summary, these findings make it clear that binocular vision makes important contributions to both the planning and the on-line control of skilled, visually guided reaching and grasping movements.     

Progressive relaxation as a function of procedural variations and anxiety level

Progressive relaxation is subject to many procedural variations. Although most investigators follow the 5-7 s tension interval advocated by Bernstein and Borkovec (1973), longer tension intervals may contribute to greater relaxation effects. This study compared tension intervals of 5, 15, and 45 s. Since the development of control over muscle tension requires attention to feedback signals, a focus on internal proprioceptive sensations was contrasted with an external condition in which the subjects silently subtracted numbers immediately following the tension-release cycle. Longer periods of tension resulted in lower EMG levels, with the 45-s tension interval producing the greatest relaxation. Those individuals who focused on physiological sensations during training were able to achieve greater levels of relaxation after the training phase was completed. There was a significant interaction between tension interval duration and focusing; subjects in the 45-s interval who focused on physiological functioning showed the greatest arousal reduction. Anxiety level did not differentially influence the effects of procedural variations in training. Clearly, additional parametric studies in relaxation training are needed.     

Transfer of motor performance in an obstacle avoidance task to different walking conditions

The aim of this study was to examine whether subjects who have learned a skilled locomotor task can transfer the acquired performance to conditions involving either a change in the external coordinates or in the sensory input from one leg. Subjects were trained to step over an obstacle with minimal foot clearance without visual information about either the obstacle or their legs during treadmill walking. Leg muscle activity and joint kinematics were recorded and analyzed. Acoustic signals provided feedback about foot clearance over the obstacle. After successful training, the transfer of learning between level and downhill walking and to walking with additional weight attached to the leg was examined. It was found that once subjects learned to step over the obstacle at an optimal foot clearance, they could transfer their performance within the first step over the obstacle in the new walking conditions. Closer examination of the transfer between level and downhill walking revealed no consistent kinematic strategy across subjects. To transfer the learned performance to walking with additional weight, subjects consistently and automatically increased biceps femoris muscle activation. The results are discussed in the context of emerging concepts in the neural control of walking and motor learning.     

Self Control of Stress-Induced Cardiovascular Change Using Transit Time Feedback

Forty-eight normotensive subjects underwent one of four training conditions: Transit time plus stress (TTPS), Transit time minus stress (TTMS). False feedback plus stress (KF), and a stress only Control (C). In the first session, all subjects received an arithmetic stressor but without training. In the second and third sessions, subjects received training appropriate to their conditions. The TTPS and FF groups received arithmetic stressors prior to the transit time training, whereas the TTMS group rested prior to training. Training in the TTPS and TTMS groups consisted of beat-to-beat pulse transit time feedback. During the training period the FF group received bogus feedback. In the fourth session, all subjects received the stress-or followed by instructions to lower blood pressure (increase transit time). No feedback was available. Significant transit time decreases occurred in response to the stress in all groups during the first session. However, in the fourth session, the TTPS group showed virtually no transit time decrease during the stressor, while the remaining three groups continued to show significant transit time decreases to the stressor. It was concluded that self control over the subjects' reactivity to the arithmetic stressor had occurred in the transit time plus stress group. This effect did not appear to be due solely to either repeated exposure to the stressor or to learned control via feedback training. Rather, the effect seemed to result from the combination of exposure and training.     

Biofeedback vs. instructional control of skin temperature

The purpose of this study was twofold: (1) to determine the effects of instructions vs. biofeedback on the development of skin temperature self-control and (2) to assess how well learned control over temperature can be retained over time. Sixty female subjects were assigned to one of six groups: (1) response-specific instructions plus feedback, (2) thermal suggestions plus feedback, (3) instructions to rest plus feedback, (4) response-specific instructions without feedback, (5) thermal suggestions without feedback, and (6) instructions to rest without feedback. All subjects participated in five training sessions on 5 consecutive days and two follow-up sessions spaced 1 week and 2 weeks after training. Subjects given either feedback and response-specific instructions, feedback and thermal suggestions, or no feedback and thermal suggestions were able to produce significant increases in digital skin temperature consistently after three training sessions. Subjects in these groups retained the ability to control skin temperature both 1 and 2 weeks after training. Subjects in the remaining conditions showed no evidence of learned control over skin temperature.This article is based on a dissertation submitted to Ohio University in partial fulfillment of the requirements for the Ph.D. degree. Portions of this article were presented at the annual meeting of the Association for the Advancement of Behavior Therapy, New York, 1976.     

Acquisition of the control of a novel muscular activity by electromyograph biofeedback

Present study aimed at to examine the process that people acquire the control of a novel muscular activity, of which they have had little experience of voluntary control, by electromyograph (EMG) biofeedback. Thirty undergraduate students who were unable to move their ears served as subjects. They were asked to give tension unto the m. auricularis posterior (the muscle to draw an ear backward). A factorial design was employed with two levels of strategy (transferring, non-transferring) and three methods of how to provide with the EMG feedback signals from the m. auricularis posterior during training session (no-feedback, biofeedback, intermittent biofeedback). The experiment was consisted of four sessions: rest, pre-test, training, and post-test. Main results were as follows: (1) Two groups, which subjects used the transferring strategy and the feedback signals, significantly increased the integrated EMG of the m. auricuralis posterior from pre- to post-tests. (2) Furthermore, the EMG-increase was significantly greater in one group, which feedback signals were intermittently given at every other training trial, than another group, which feedback signals were given at all trials. (3) It was also found that no increase of awareness to the muscular tension occurred despite the increase of EMG activity.     

The impact of stress experience on heart rate and task performance in the presence of a novel stressor

The impact of prior stress experience on heart rate and task performance in the presence of a novel stressor was studied. During a training phase 42 female students were required to solve arithmetical problems under conditions of either no stressor, delayed auditory feedback, or distraction. Subsequently in a testing phase all subjects performed the same task in the presence of delayed auditory feedback. Training in the presence of stress resulted in decreased heart rate and better performance in the testing phase. These data were interpreted as supporting the hypothesis that training under stress-inducing conditions increases stress resistance which generalizes to a novel stressor and which leads subjects to experience the novel stressor as being less stressful.     

The observational learning in mentally retarded children: the effects of mediational sentences on paired-associate learning

Thirty-eight mentally retarded children and 44 normal children learned a paired-associate picture list under one of four conditions. Subjects in E1 group were exposed to the model who learned the same list by means of formulating mediational sentences directly prior to learning by themselves. Subjects in E2 group were exposed to the model who learned the different list by means of formulating mediational sentences. Subjects in E3 group were exposed to the model who learned the same list without mediational sentences. control subjects learned the paired-associate list without observing the model. The results indicated that retarded and normal subjects in E1 group performed significantly higher than subjects in E2, E3, and control groups. The modeling of verbal elaboration was proved.     

Effect of Feedback Sensitivity Upon Learned Heart Rate Acceleration

Twelve undergraduate volunteers received 12 sessions of heart rate biofeedback training involving one of two experimental conditions. One-half of the subjects received 4 sessions of high sensitivity analogue heart rate biofeedback, followed by 4 sessions of low sensitivity feedback, and then, 4 final sessions of high sensitivity feedback. The other half of the subjects received the exact opposite order of feedback conditions. All subjects were instructed to accelerate heart rate during 8 trials in each session. The results were contrary to the hypothesis derived from a motor skills model of visceral learning, i.e., the low feedback sensitivity condition consistently produced larger magnitude heart rate acceleration in comparison to the high sensitivity condition. These findings were discussed in terms of methodological suggestions for future research and in terms of the motor skills model of visceral learning.     

The Effects of Feedback Sensory Modality, Feedback Information Content, and Sex on Short-Term Biofeedback Training of Three Responses

In three factorial experiments, auditory vs visual vs tactile feedback, analog feedback vs analog feedback which was anchored, and sex, were varied to assess the effects of these variables on performance in short-term biofeedback training of heart rate reduction, hand temperature increase, and forehead muscle tension reduction. A total of 108 subjects served in the study. Moderate but reliable changes were found during the course of the training session for all three physiological responses. The ability to reduce heart rate in a single training session did not appear to be a function of any of the variables manipulated in this study, but rather could be attributed to adaptation. In both muscle tension and temperature training, however, there were significant interactions between sex and sensory modality of the feedback stimulus and, in the case of muscle tension training, between information content of the feedback signal and sex. The overall pattern of results indicated that performance during biofeedback training is a complicated function of sex and the type of signal used to provide feedback, and that this function is not constant across physiological response systems.     

The processing unit and story structure in memory for story

To investigate story memory, three experiments were conducted. In Experiment I, 60 professional school students were asked to sort the sentences of stories into groups. Hierarchical clustering analysis was used to generate perceived story structure. Results indicated generally a good agreement between perceived structure and the structure induced by story grammar. In Experiment II and III, 72 university students and 72 professional school students learned three stories and were tested in recognition task. In the course of presenting the sentences in story, pauses were inserted between story clusters (BP) or within them (WP) (Experiment II). In BP condition, recognition time (RT) was faster than in WP condition. In Experiment III questions were inserted at the same points as in Experiment II (BQ, WP). In BQ condition RT was faster than in BP condition. These results indicated that pause or question inserted at the boundary of story cluster facilitated story processing and that question was more effective than pause. Story was processed in unit corresponding to perceived story structure.     

Biofeedback as a treatment for postural hypotension

Two patients with cervical spinal cord lesions were treated for postural hypotension using auditory and visual feedback for voluntary increases in blood pressure. Following initial measures of blood pressure, feedback was delivered for systolic increases above baseline. Within several weeks, both patients learned to increase their pressure markedly from the start of training sessions to their conclusion. The patients' legs were progressively lowered during and at the end of training sessions without significant blood pressure decreases. Long-term follow-up indicated that they were able to maintain the learned increases in blood pressure despite adverse medical conditions. It is suggested that central nervous system damage disrupts homeostatic regulation, permitting greater voluntary control through biofeedback as a new feedback loop. Motivation is also considered an important variable for success.     

Remapping hand movements in a novel geometrical environment

The issue of how the Euclidean properties of space are represented in the nervous system is a main focus in the study of visual perception, but is equally relevant to motor learning. The goal of our experiments was to investigate how the properties of space guide the remapping of motor coordination. Subjects wore an instrumented data glove that recorded the finger motions. Signals generated by the glove operated a remotely controlled endpoint: a cursor on a computer monitor. The subjects were instructed to execute movements of this endpoint with controlled motions of the fingers. This required inverting a highly redundant map from fingers to cursor motions. We found that 1) after training with visual feedback of the final error (but not of the ongoing cursor motion), subjects learned to map cursor locations into configurations of the fingers; 2) extended practice of movement led to more rectilinear cursor movement, a trend facilitated by training under continuous visual feedback of cursor motions; 3) with practice, subjects reduced motion in the degrees of freedom that did not contribute to the movements of the cursor; 4) with practice, subjects reduced variability of both cursor and hand movements; and 5) the reduction of errors and the increase in linearity generalized beyond the set of movements used for training. These findings suggest that subjects not only learned to produce novel coordinated movement to control the placement of the cursor, but they also developed a representation of the Euclidean space on which hand movements were remapped.     

Alpha 2-adrenergic receptor function in patients with unipolar and bipolar affective disorders

Alpha 2-adrenergic receptor function was measured in platelets from unipolar (UP) depressed, bipolar (BP) depressed, and bipolar euthymic patients and normal control subjects. Only the platelets from UP depressed patients were different from control in having an increased number of alpha 2-receptors, a decreased percent norepinephrine inhibition of prostaglandin E1 (PGE1)-stimulated cyclic AMP (cAMP) production, and a decrease in PGE1 stimulation of cAMP production. Platelets from BP patients, depressed or euthymic, were not significantly different from control subjects. These preliminary data suggest that alpha 2-adrenergic receptor function and PGE1 stimulation of cAMP production are diminished in UP patients.     

Sleep spindle activity changes in patients with affective disorders

Various polysomnographic sleep patterns are associated with affective disorders, but very little is known about sleep spindle characteristics in adult depression. In primary endogenous depressive male patients (unipolar, UP, and bipolar, BP) with comparable depression scores and in normal control subjects recorded during 3 consecutive nights, no night effect was observed on the sleep variables investigated except for REM latencies of stages 1 and 2. Stage 2 duration and variables related to sleep spindle characteristics (the number and the density of spindles of 1/2 s; the number and the density of full spindles of stage 2 over the 3 nights) were significantly lower in depressed patients than in control subjects, the mean number of spindles being lower in UP than in BP patients. Sleep spindle measures were clearly negatively correlated with age in the overall group (i.e., depressed plus control subjects). They were also negatively correlated with the REM latencies of stages 1 and 2 in BP depressed patients, whereas this relation was not observed in UP patients.     

Effects of body control and attention on body sway induced by a tilting room

The purpose of this study was to examine the effects of body control and attention on body sway that was induced by a "tilting room". With an initial instruction, 18 subjects were divided into two groups: target and body attention groups, and then stood on a stabilometer in a room that tilted forwardly. Body sway that was induced by the tilting room was measured with the stabilometer. During the training session, subjects received Dohsa training (Naruse, 1973) in order to control their body movement. Analyses indicated the following: (1) Subjects swayed in the same direction as tilting of the room; (2) No difference in the body sway was found for the two groups before training; and (3) After training, subjects increased the controllable area on the stabilometer and learned to use their bodily sensation better. Subjects in the target attention group had a greater increase in body sway than the other group. These results suggest that adult flexibility appeared in an ecological situation where conflicting information was received through visual and bodily sensation.