José Chaves, MD

| Significance | History | What Is | Applications | Modalities | Working | Advantagens | Bibliografy | The Author |


In the USA the 90ís have been considered the decade of the brain. Scientific progress related to brain functioning has been so great that the expression is fully justified. Technological growth has allowed the development of various techniques in the approach to the mind and the body at a level never before imagined.

These techniques are the modern TECHNOLOGIES OF THE MIND, which include biofeedback, mind-machines (devices for cerebral stimulation by light and sound), CES (devices for electric stimulation of the brain), the techniques of accelerated learning, etc. Among these, biofeedback stands out as the most revolutionary and promising approach to mental and corporal functioning, and therefore can be considered as one of the therapies most likely to prevail in the 21st century .

This kind of therapy , prevalent in developed countries as the USA, Japan, Canada, France, etc., has been showing an extraordinary rate of growth and sophistication at a level and development inconceivable one or two decades ago. In Brazil such a therapeutic modality has just now been introduced. The ignorance in our field about what is the therapy of biofeedback is of a surprising dimension, still more so if we consider the ease of which access to an immense amount of information can be obtained these days. Without looking into the reasons that can justify such ignorance, we intend, in this article, to bring to light the basic information that allow us to clearly understand of what biofeedback therapy consists.

Imagine a hiperactive child , one that canít stop moving, that is unable to do his school duties, that is disturbed and unruly, that is inattentive and slovenly with everything, one that only wants to play and have fun. It is the kind of youth that has already changed schools many times, has been considered as a "small devil" by the neighborhood and whose parents don't know any more what they can do to inspire a sense of responsibility and peacefulness in their child. Through an appropriate device, connected to a computer, this child is given a game to play (the one that in fact, they adore). A few months later the child is calmer, staying seated and achieving school duties.

Miracle? No. In reality the game is a special program, used to train the child to modify some cerebral waves, exactly those, in fact, that were previously responsible for the disturbed behavior. In the same way, we can help people dominate many other psychological or physical conditions, allowing them to get relief for the symptoms these conditions cause.



When you program an air conditioning machine to maintain the temperature of a room, for example, between 20°C and 25°C, the following happens: if the temperature of the room reaches 25°C, a sensor detects that value and sends an order to the machine to cool the room. The cooling then causes the temperature to drop and when it arrives at 20°C, the sensor detects this and sends a new order to the machine: to stop the cooling. If the temperature rises to 25°C again, the cycle resumes and so it goes indefinite and automatically. This is the mechanism of the feedback : to correct the course of a process, intervening in a previous point of its development or cycle.

When you use a thermometer to measure your fever or you get on a scale to verify your weight, you are using an identical procedure. The information given by the thermometer or by the scale causes you to behave in some way, to lower the fever (through a medication ) or to decrease the weight (with diet, exercises). If your fever or weight increases, you will take new measures to get them under control. When the thermometer informs you that your temperature has returned to normal, or the scale informs you that you have reached the desired weight, then you interrupt the treatment or the diet. Biofeedback is the application of this idea to internal biological processes.


The knowledge that we have had about the operation of the Autonomic Nervous System was that it commands a group of unconscious, involuntary and autoregulated biological functions. Self-regulation was conceived as an unalterable process, where rigid laws defined the modus operandi of functions such as heart rhythm, breathing frequency, and blood flow among many others.

In 1960, Neal Miller, one of the most renowned experimental psychologists of our time, manifested his conviction that the biological functions under the control of ANS could be manipulated and placed under conscious control through instrumental learning (operant conditioning). Miller believed that if there was an indicator revealing the state of some of those functions, it would be possible to condition it, in the same way it would be possible to condition the functions of the Somatic Nervous System.

After overcoming certain technical difficulties, Miller demonstrated unequivocally the feasibleness and the success of his suppositions. If Pavlov had demonstrated the possibility to condition salivation in dogs with the sound of a bell, Miller went beyond and showed that it was possible to condition animals to regulate the amount of their salivation, for more or for less. Since that time laboratory experimentation has confirmed the viability of conditioning a range of autonomous functions. With technological development, mainly in the area of the computation, conditions were created for the instantaneous control of a group of autonomous functions in human beings. And so was born biofeedback.



It is a technique to learn voluntary control of physiologic functions of which people are usually not aware, with the purpose of recovering, to maintain or to improve the health and/or performance. That is done through the use of some devices that measure accurately and instantly the physiological function under study, informing the subject, with visual or audible signals, the valur of the physiological parameters which are being monitored. With this information, and guided by the biofeedback therapist, the subject has the possibility of altering such values, according to their will and in order to change them to a more desirable level. With repeated training, supervised by the biofeedback therapist, the subject can condition such physiological process to work in a stable and desired way.



The biofeedback is a revolutionary therapy and everything indicates that it will be a therapy for the future. Its application field is very broad and aplications appear in new areas every day. At the present time it has been applied with success to the following conditions and disturbances:

1. Alls manifestations of stress, fatigue and syndrome of chronic fatigue.

2. Anxious states, phobias, syndrome of panic, obsessive-compulsive disturbance (OCD).

3. Depression.

4. Learning disabilities, especially ones related to attention deficit with or without hyperactivity (ADD/ADHD).

5. Alcoholism and drug addiction.

6. Migraine and tension headaches.

7. Chronic back pain, in the nape and shoulders, etc.

8. Essential arterial hypertension, heart arrhythmia.

9. Muscle problems like sprain, bruxism, repetitive strain injuries, etc.

10. Rehabilitation in sequels of stroke (spasticity or flaccid), cerebral concussion, cerebral palsy.

11. Asthma and allergic diseases.

12. Raynaudís disease.

13. Insomnia.

14. Fecal and urinary incontinence.

Besides its therapeutic aspect, biofeedback is an educational tool, used to improve performance. In this sense, it has been applied to Olympic teams (USA, Canada, Japan) aiming to help athletes reach optimal performance (peak performance). However the training of optimal performance isn't limited to the sporting sphere. It is also being applied to other performing classes, such as the executive, educational, and the communication domains, etc.


The classical modalities of biofeedback are the electrodermal (GSR, EDR or EDA), the thermal (TEMP), the electromyographic (EMG) and the electroencephalografic (EEG), or neurofeedback. The electrodermal biofeedback (Galvanic Skin Resistance, Electrical Dermal Response or EDA) consists in the passage of an electrical microcurrent (insensible) by the surface of the skin, measured by the resistance of this passage. When the sweat glands are active, the resistance to the passage of the current decreases. Otherwise, the resistance increases. The measure of the electrical resistance express the activity/ inactivity of the sweat glands which, for its time, are a reflex of the activity of the sympathetic nervous system.

A PC software for recording and analysis of the physiological response of patients under treatment by biofeedback. p. Peak-to-Peak Amplitude shows the amplitude of the response of the arterial pressure of the subject between two consecutive heart beats. Heart Rate shows a graph with the fluctuation of heart frequency in function of time, and GSR Value shows the decrease of the galvanic skin response during response training.

As one can see, this is a modern version of the old lie detector. The analysis of the pattern of electrical responses of the skin allows us to establish the correlation between emotional state and the activity of the sympathetic system and by this way to find the best condition for each individual.

The thermal biofeedback (TEMP) consists of the changing of temperature in the fingers of the hands or of the feet, a change that is in direct correlation with vasodilation/ vasoconstriction conditions in such places. The vasodilation is accompanied by increases in temperature, while vasoconstriction that implies a fall in temperature. This allows us to know about the subject's emotional and physical conditions, expressed by the activation/ deactivation of the autonomous nervous system (sympathetic/parasympathetic).

By this way, the vasomotor control can be worked out and conditioned (in both senses), which will allow, for example, the relief of a migraine or vasogenic peripheral diseases, such as Raynaud's.

The electromyographic biofeedback (EMG), on the other hand, consists of measuring the electric activity of the muscles which expresses their degree of contraction/ relaxation. By this way it is possible to train the individual to strengthen the musculature when it is indicated or to relax when it is the case.

Modern computerized stand-alone device
for electromyographic biofeedback training
A system which can be coupled to a microcomputer for
monitoring and analysis of EMG

The neurofeedback or electroencephalographic biofeedback consists of measuring the electric waves of the brain, just as it happens in the classical EEG. So it is possible to train the individual to produce or to decrease their production (amplitude and/or frequency) of any one of the bands of cerebral waves, in any of the cerebral hemispheres, or in both, according to the physical and subjective state that it aims to reach.

Besides the four mentioned modalities we should still mention heart biofeedback (ECG) which measures and controls the heart frequency and arterial pressure, and respiratory biofeedback, where the breathing type (thoracic/ diaphragmatic) and breathing frequency are controlled.

EEG topography examination permits the selection of spatial patterns of distribution of electrical activity of the brain in determined areas of the patient's head, and thus to perform biofeedback training only for a particular combination, or "signatures". This application requires 20 to 30 channel recording and sophisticated software and hardware for recording, analysis and real time recognition of the signatures. There are known signatures and protocols for many disease conditions.


It is performed through one to three weekly sessions of 30 to 50 minutes each. The total duration of the training is variable, according to the modality and the disturbance to be treated. An average of 20-40 sessions is generally considered. However, a decrease has been observed in the number of sessions year after year, according to the therapist's experience and the growing technological development that has been allowing the construction of more sophisticated and efficient devices.


Biofeedback therapy is a technique whose application is not of exclusive use of a particular professional class. It can be performed by professionals in different areas, specially in the health area (physicians, psychologists, dentists, nurses, etc.) and in the educational area. The fundamental requirement is a proper training in human psychophysiology. This implies a specialization course and technical and scientific training for the acquisition of knowledge and the development of skills in the practice of the biofeedback therapy.


The biofeedback therapy presents many positive points when compared with other kinds of treatments. Unlike what happens in the treatment by drugs, biofeedback therapy doesn't present side effects. It is also not nearly invasive as are surgeries. Furthermore it is a therapy which is practically free of hazards for the patient, and completely painless. Another point to be mentioned is that the patient has the control of the evolution of the therapy. The conscious and voluntary participation of the patient plays a decisive part in the success of the therapy. As was already mentioned, biofeedback is not only a therapy. Its educational aspects causes a modification of habits and behaviors leading tmany times o a reorganization in the life of the patient.


See AlsoResources about Biofeedback on the Internet

Picture credits: Biofeedback Instrument Corp., EEG Spectrum, Lexicor Instruments, Thought Technology Ltd.

The Author

Dr. José Chaves, MD, specialist in Psychiatry - Psychotherapy - Biofeedback therapy. Coordinator of the Laboratory of Applied Psychophysiology and Biofeedback - Department of Psychology-Federal University of Uberlândia, Minas Gerais, Brazil. Full Professor of the Department of Psychology of the Federal University of Uberlândia. Tel.: (034)236-4057/ 234-0915 E-mail: