What are Biofeedback and Neurofeedback?
Feedback is an process which reflexively changes itself using its own forceful flow. The classic feedback device is the steam valve. As the steam causes a rotor to turn the centrifugal force of the rotation causes levers to rise, or strings to fly out, in the same way that if you rapidly turn yourself, your arms fly outward.
The levers on a steam device control the flow of steam, the faster the rotation the smaller the steam vent, the smaller the vent the slower the rotation. The size of the vent, the speed of rotation and the force of the arms closing the valve can all be adjusted so that the rotating axle maintains a consistent speed, so long as the supply of steam is constant.
Over one hundred years ago, French physiologist, Claude Bernard, who was characterized by Louis Pasteur “Physiology Itself” noted that most all of the human body’s systems are feedback regulated. In fact, they remain quite constant regardless of changes in the external environment. In 1932, Walter Cannon coined the term homeostasis to describe internal dynamic constancy.
A man eats food, his mouth fills, juices flow, his stomach fills, and his sensors send a signal, “satisfied.” He stops eating. A woman trots upstairs a bit too fast, her oxygen sensors are starved, and she starts breathing more deeply and quickly.
I glance out the window, the sun has moved to bounce off the white wall of the bank next door, my pupils contract, and I turn back toward the darkest wall of the room, or dash into my dark room. My pupils dilate.
Generally, body systems regulate through positive and negative feedback loops. The body has sensors that detect deviation from its normal internal range. This deviation activates effectors that essentially reverse the condition.
Such ordinary biological feedback of daily living can be enhanced by using mechanical transducers (devices which measure energies). I can press a piece of plastic against my palm which turns color depending on my temperature. Quickly I learn to make the color redder and redder (the color is arbitrary, it could be bluer and bluer). If I am prone to headaches I can prevent, inhibit, or relieve a headache by warming my hand. I may measure the way my skin conducts electricity and can learn to make my own skin less conductive which tends to relax me. The plastic has fed the information back to my conscious mind and my brain has learned consciously to warm my hand. My body is responding to a feedback loop. According to Merriam Webster, biofeedback is: “the technique of making unconscious or involuntary bodily processes (as heartbeats or brain waves) perceptible to the senses (as by the use of an oscilloscope) in order to manipulate them by conscious mental control.”
Early in the development of biofeedback attention was first focused on temperature (TEMP) change. Temperature is easily and cheaply monitored and learned change is markedly reliable. Muscle tension (EMG) soon came along. The techniques of measuring muscle tension are perhaps as easily done as temperature measurement; but the equipment is more costly. TEMP and EMG are the most widely practiced forms of biofeedback.
In 1970 Barry Sterman noted that he could readily train cats to strengthen the amplitude of signals at 13 pulses per second generated in the brain’s Fissure of Roland. Later he observed that cats trained to make stronger 13-14 Hz signals resisted epileptogenic drugs (specifically, injected hydrazine). D.A.Quirk, a Canadian penologist, and G.von Hilsheimer, a Florida neurofeedback specialist, applied Sterman’s 1970 method to 2776 felons imprisoned in the Ontario Correctional Institute near Toronto and to about 10,000 clients seen in hospital and in outpatient care. The recidivism in these prisoners (15% in 3 years after discharge, compared to 40 – 100% in typical prisons) reduced significantly.
Subsequently a professional movement has been created using EEG biofeedback in the treatment of ADHD (pioneered by Professor Lubar at the University of Tennessee). In Europe a significant network of practitioners has been organized by Prof. Dr. Jiri Tyl of Prague who has significantly contributed to the proof of the efficacy of EEG biofeedback (see EEG Biofeedback FAQ)
Neurofeedback is a specific type of biofeedback that makes brainwaves perceptible through the use of sensors attached to the head. The brain operates by sending minute electrical impulses to the many cells that comprise it. When the brain is excited it emits a specific frequency range of waves. The same is true if it is tired or focused. This process is similar to a radio tower that gives off radio waves. Brainwave sensors called electrodes monitor brainwaves emanating from the brain much the same way a radio receiver monitors different radio frequencies – if I change my car radio from 101.5 FM to 107 FM, I get to listen to a different station. So, the sensors pick up these signals like little radio antennae. A receiver, like a radio receiver, amplifies them and sends them to a computer where they are changed to sound and/or pictures on the computer monitor. The pictures and sounds make the current state of the brain perceptible because that information is displayed via sound and pictures on the computer screen. So, if a person is overly excited, she can see this on the screen in a graph or perhaps a screen character rapidly buzzing around. If she wishes to calm herself, she learns to slow the computer character which is reflecting the necessary relaxing brainwave pattern. By repeating this process many times, she can eventually learn to place her brain and body in a calm state without the neurofeedback equipment. This learning achieved by biofeedback is robust, stable, reliable, and readily acquired.
There is significant evidence that hyperactive boys tend to make high amplitude slow brain waves which are associated with inefficient faster brain waves. The child can be taught to reduce the amplitude of signals slower than 7 pulses per second (<7 Hz for Hertz) and to increase the strength of the signals running 13-14 Hertz. Such children tend to become more social, more effective at school work, and they perform more adroitly on IQ and other tests. One can think of this process as switching radio stations at will. Neurofeedback students learn to switch from inattentive (daydreaming) states to focused states at will.
George von Hilsheimer, Ph.D., F.R.S.H., and Peter Freer, MAEd