What is biofeedback?

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The learned self-regulation of the autonomic nervous system through monitoring of the physiological activity occurring within an individual
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Indications and Procedures

Biofeedback has been utilized in both research and clinical applications. The term itself denotes the provision of information (feedback) about a biological process. It has been found that individuals (laboratory animals included), when given feedback that is reinforcing, are able to change physiological processes in a desired direction; homeostatic processes being what they are, these changes are in a positive direction. In the case of humans, the feedback is provided about a physiological function of which the individual would not otherwise be aware were it not for the provision—via a biodisplay—of information about that process.

Human maladies range from the purely structural to the purely functional, with various gradations. An example of a structural disorder is a broken bone, while an example of a functional disorder might be a person who manifests symptoms of blindness for which there is no known or identifiable organic cause. Looking at the spectrum of human maladies, one can consider the continuum as “structural,” “psychophysiological,” “mental-emotional,” “hysterical,” and “feigned.” The category of psychophysiological lies midway between structural and mental-emotional. A psychophysiological disorder has elements of both mind and body interactions; it is a physiological disorder brought about by thoughts, feelings, and emotions. There are those who take the position that all human maladies and disorders have a mental-emotional component to them, that there can be no change in the mental-emotional state without a corresponding change in the physiological state and no change in the physiological state without a corresponding change in the mental-emotional state.

It is currently the preference of many scientifically and technologically oriented practitioners to deal with the more structural disorders (or to treat the disorder as if it were mostly structural). It is also the case that many mental health practitioners prefer to deal with disorders that fall more into the mental-emotional category. A growing number of practitioners, however, have an interest in and training for dealing with psychophysiological disorders. This emerging field is referred to as behavioral medicine, and a large percentage of the practitioners in this field employ biofeedback as a modality.

A classic example of biofeedback being used to correct a physiological problem would be the employing of electromyograph (EMG) biofeedback for the correction of a simple tension (or psychophysiologic) headache. The headache is caused by inappropriately high muscle tension in the neck, head, or shoulders. In surface electromyographic biofeedback, the biofeedback practitioner attaches electronic sensors to the muscles of the forehead, neck, or shoulders of the patient. The electronic sensors pick up signals from electrochemical activity at the surface of the skin in the area of the involved muscle groups. The behavior of the muscles being monitored is such that minute changes in the electrochemical activity in the muscles—tension and relaxation—occur naturally.

The sensitivity of the biofeedback instrument (the magnification of the signal may be as high as one thousand times) and the display of the signal make the individual aware of these changes via sound or visual signals (biodisplays). When the biofeedback signal indicates that the muscle activity is in the direction of relaxation, the individual makes an association between that muscle behavior and the corresponding change in the strength of the signal. The individual can then increase the duration, strength, and frequency of the relaxation process. Having learned to relax the involved muscles, the individual is able to prevent or abort headache activity.

It is axiomatic that any physiological process (behavior) that is capable of being quantified, measured, and displayed is appropriate for biofeedback applications. The following are some of the more commonly used biofeedback instruments.

An electromyograph is an instrument that is capable of monitoring and displaying information about electrochemical activity in a group of muscle fibers. Common applications of surface electromyography (in which sensors are placed on the surface of the skin, as opposed to the insertion of needles into the muscle itself) include stroke rehabilitation. Surface electromyography is also used in the treatment of tension headaches and fibromyalgia.

An galvanic skin or electrodermal response (EDR) biofeedback instrument is capable of monitoring and displaying information about the conductivity of the skin. An increase in the conductivity of the skin is a function of moisture accumulating in the space recently occupied by blood. The rate of blood flow depends on the amount of autonomic nervous system arousal present within the organism at the time of measurement. The higher the level of autonomic nervous system arousal, the greater the amount of skin conductivity. Common applications of EDR biofeedback are the reduction of anxiety caused by phobic reactions, the control of asthma (especially in young children), and the treatment of sleep disorders. For example, many insomniacs are unable to drop off to sleep because of higher-than-appropriate autonomic nervous system activity.

An instrument that is capable of monitoring and displaying the surface temperature of the skin, as correlated with an increase in vascular (blood flow) activity in the area of the skin in question, can also be used for biofeedback. Such an instrument is helpful in treatment for high blood pressure and migraine headaches.

Electroencephalographic (EEG) biofeedback involves the monitoring and displaying of brain wave activity as a correlate of autonomic nervous system activity. Different brain waves are associated with different levels of autonomic nervous system arousal. Common applications of EEG biofeedback are in the treatment of substance abuse disorders, epilepsy, attention-deficit disorders, and insomnia.

Heart rate variability (HRV) biofeedback monitors and displays the changing intervals between heart beats. Studies have indicated that HRV biofeedback may be beneficial in treating cardiovascular, respiratory, and emotional conditions.

Uses and Complications

Biofeedback is gaining in popularity because of a number of factors. One of the principal reasons is a growing interest in alternatives to the lifetime use of medications to manage a disorder.

To understand the rationale for biofeedback in a clinical setting, it is essential to discuss the types of disorders for which it is commonly employed. As pointed out in the National Institute of Mental Health's publication Biofeedback, the more common usages of biofeedback treatment techniques include “migraine headaches, tension headaches, and many other types of pain; disorders of the digestive system; high blood pressure and its opposite, low blood pressure; cardiac arrhythmias (abnormalities, sometimes dangerous, in the rhythm of the heartbeat); Raynaud’s disease (a circulatory disorder that causes uncomfortably cold hands); epilepsy; paralysis and other movement disorders.”

Thus, biofeedback can be safely and effectively employed in the alleviation of numerous disorders. One example worth noting—in terms of the magnitude of the problem—is the treatment of cardiovascular disorders. Myocardial infarctions, commonly known as heart attacks, are one of the major health problems in the industrialized world and an area of special concern to those practitioners with a psychophysiological orientation.

One of the principal causes of heart attacks is hypertension (high blood pressure). Emotions have much to do with the manifestation of high blood pressure (hypertension), which places this condition in the category of a psychophysiological disorder. Researchers have demonstrated that biofeedback is an effective methodology to correct the problem of high blood pressure. The data reveal that many individuals employing biofeedback have been able to decrease (or eliminate entirely) the use of medication to manage their hypertension. Studies also show that these individuals maintain normal blood pressure levels for as long as two years following the completion of biofeedback training.

Because of its noninvasive properties and its broad applicability in the clinical setting, biofeedback is also increasingly becoming one of the more commonly utilized modalities in many fields, such as behavioral medicine. Researchers have provided documented evidence showing that biofeedback is effective in the treatment of so-called stress-related disorders. Research has also shown that biofeedback has beneficial applications in the areas of neuromuscular rehabilitation (working with stroke victims to help them develop greater control and use of afflicted muscle groups) and myoneural rehabilitation (working with victims of fibromyalgia and chronic pain to help them obtain relief from debilitating pain).

Research in the 1960s pointed to the applicability of EEG biofeedback for seizure disorders, such as epilepsy. Advanced technology and later research findings have demonstrated EEG biofeedback to be effective in the treatment of attention-deficit disorder, hyperactivity, and alcoholism as well.

Biofeedback appears to have particular applicability for children. Apparently, there is an innate ability on the part of the young to learn self-regulation skills, such as the lowering of autonomic nervous system activity, much more quickly than older persons. Since this activity is highly correlated with respiratory distress, biofeedback is often used in the treatment of asthma in prepubescent children. Biofeedback is also being successfully used as an alternative to prescription medications (such as Ritalin) for youngsters with attention-deficit disorder.

The use of biofeedback is also found in the field of athletics and human performance. Sports psychologists and athletic coaches have long recognized that there is an inverted U pattern of performance where autonomic nervous system activity and performance are concerned. In the field of sports psychology, this is known as the Yerkes-Dobson law. The tenets of this law state that as the level of autonomic nervous system arousal rises, performance will improve—but only to a point. When autonomic nervous system arousal becomes too high, a corresponding deterioration in performance occurs. At some point prior to an athletic competition, it may be desirable for an athlete to experience an increase (or a decrease) in the level of autonomic nervous system activity (the production of adrenaline, for example). Should adrenaline levels become too high, however, the athlete may “choke” or become tense.

To achieve physiological autoregulation (often referred to in this athletic context as "self-regulation"), athletes have used biofeedback to assist them with establishing better control of a variety of physiologic processes. Biofeedback applications have ranged from hand-warming techniques for cross-country skiers and mountain climbers to the regulation of heartbeat for sharpshooters, such as biathletes and archers, to the lowering of adrenaline levels for ice-skaters, gymnasts, and divers.

Biofeedback, apart from empirical studies or research on both animal and human subjects, is seldom used in isolation. In most treatment protocols, it is employed in combination with such interventions as behavioral management, lifestyle counseling, exercise, posture awareness, and nutritional considerations. In most biofeedback applications, the individual is also taught a number of procedures that he or she is encouraged to use between therapy sessions. The conscientious and effective practice of these recommended procedures has been proven to be a determining factor in the success rate of biofeedback. The end aim of biofeedback is self-regulation, and self-regulation must extend to situations outside the clinical setting.

Biofeedback (when employed as a part of a behavioral medicine program) is usually offered as a component of a treatment team approach. The biofeedback practitioner commonly interfaces with members of other disciplines to design and implement a treatment protocol to correct the presenting problem (for example, fibromyalgia) for which the referral was made.

One commonly found model of biofeedback is for the patient, the biofeedback practitioner, and the primary medical care provider to constitute a team. The team concept applies even to the extent that the biofeedback practitioner (in many ways acting as a coach) will give the patient a number of procedures to follow between treatment sessions and will then evaluate, with the patient and the medical practitioner, the effectiveness of the procedure. Modifications in the modalities and in the interventions follow from these evaluations. Biofeedback interventions are dynamic and measurable so that the effectiveness of the protocol can be adjusted to meet the needs of the patient.

Perspective and Prospects

Biofeedback, as a treatment modality, is relatively new. The history of biofeedback as a research tool, however, dates back to early attempts to quantify physiological processes. From the time of Ivan Pavlov and his research on the salivary processes in canines, both psychologists and physiologists have long been interested in the measurement of human behavior (including physiological processes).

Early in the twentieth century, the work of Walter B. Cannon, with his book The Wisdom of the Body (1932), helped to set the stage for the field of self-regulation. Another landmark was the 1929 publication of Edmund Jacobson’s Progressive Relaxation. More recently, the work of such pioneers as John V. Basmajian, Neal Miller, Elmer Green, Joseph Kamiya, and many others spawned research and development efforts that by 1975 produced more than twenty-five hundred literature references utilizing biofeedback as a part of a study.

The evolution of biofeedback as a treatment modality has its historical roots in early research in the areas of learning theory, psychophysiology, behavior modification, stress reactivity, electronics technology, and biomedical engineering. The emerging awareness—and acceptance by the general public—that individuals do in fact have the potential to promote their own wellness and to facilitate the healing process gave additional impetus to the development of both the theory and the technology of biofeedback treatment. Several other factors have combined to produce the climate within which biofeedback has gained recognition and acceptance. One of these was widespread recognition that many of the disorders that afflict humankind have, as a common basis, some disruption of the natural feedback processes. Part of this recognition is attributable to the seminal work of Hans Selye on stress reactivity.

Developments in the fields of electronics, physiology, psychology, endocrinology, and learning theory produced a body of knowledge that spawned the evolution and growth of biofeedback. Further refinement and an explosion of technology have resulted in procedures and techniques that have set the stage for the use of biofeedback as an effective intervention with wide applications in the treatment of numerous disorders.

A number of devices have been designed for home biofeedback use. Some are computer-based while others are stand-alone, handheld devices. Consumers interested in such equipment should consult with their biofeedback team regarding the safety and reputability of the products under consideration.

A new version of biofeedback has promising hope for people with brain damage due to injury, paralysis, or stroke. Known as "neuroprosthetics," "nanobiotechnology," or occasionally, "brain interface chips," this technology is in the early stages of research but is enabling people to control machinery with their thoughts.

Some research and clinical trial studies have shown that quadriplegic people can learn to operate a computer, manipulate a robotic arm, or play video games through the use of an implanted electrode. Signals from the chip are sent to an analog-to-digital converter, which processes the simultaneous firings of neurons into digital data. For example, if a person thinks about turning off a computer, the analog information translates this into an actual motion, controlling the cursor on the computer screen. Other research has utilized noninvasive methods of assimilating neuronal activity. In some research studies, quadriplegic persons and persons with no neuromuscular impairment could control a cursor by controlling their EEG patterns. Participants are able to do this by learning to identify, over time, feedback from brain-wave activity.

Both electrode implants and EEG methods have their positives and negatives. EEGs are a bit cumbersome, due to the wires and electronic equipment; however, wireless EEG technology in the future may be possible. Implanted electrodes may provide more precise information, but this approach requires surgery and is expensive and potentially risky.

Neither method directly affects actual movement; that is, it does not read minds but instead enables the mind to act directly on an external object. The futuristic prospect of controlling machinery with thoughts has many psychological, medical, and ethical implications that will need to be uncovered as research progresses.


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