16-08-2012, 03:19 PM
The Use of Biofeedback in Psychiatric Disorders
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Abstract
Feedback is an essential ingredient in all learning. It has been defined as a method of controlling
a system by reinserting into it the result of its past performance. Biofeedback is a particular kind
of feedback from different parts of our body such as the brain, heart, circulatory system and
muscle groups amplified by an instrument and display as visual, auditory information so that the
individual receiving this information can learn to regulate his/her own physiological functioning.
Biofeedback is useful in psychiatric disorders. It allows therapists to improve the patient’s ability
to assess psychological baseline, reactivity to stress challenges, and recoveries. Therapists can
adjust treatment as needed to meet physiological goals.
Historical Background
It was Tarchanoff who in 1885, in his classical paper concluded for the first time that
heart rate acceleration is mediated via voluntary alteration of the spinal speeding
centers and that the control of these speeding centres is mediated by the activity of
some higher cortical centres in the brain. Schafer, Caney and Tunstall (1886)
Woodworth (1901) ,Jacobson (1925) ,had contributed significantly in this area. The final
line of research which led to the field of biofeedback was work in the field of EEGwhether
subjects could voluntarily produce certain EEG patterns (Hart, 1967). Also
because of the similarity in the subjective experience of a high alpha state with that
reported for mediation , the relation of self-control of the EEG attracted much attention
from the non scientific world and thus the whole field to grow.
TYPES OF BIOFEEDBACK
There are many types of biofeedback equipments. Some are so small one can hold them
in his hand, and others involves large(expensive) instrument in a wall unit. Different
machines have been designed to receive the electrical signals from the heart, brain,
muscles, skin, back and so forth. The use of biofeedback is specific to symptoms the
patient exhibits in a particular body region. In general, though, instrumentation falls
into two categories: binary and proportional. Binary equipment provides information
that lets someone know only whether he or she is controlling a physiological function.
Electro-Myographic Biofeedback (EMG)
This biofeedback modality monitors electrical impulses produced by muscle tissue.
Electrodes are placed on the skin over specific muscles that are prone to tension, such
as the jaw, lower back, neck, and/or shoulders. For overall relaxation, the frontalis
muscle on the forehead issued, as this muscle has no direct connection to bone.
Through the EMG, the patient first becomes aware of the current level of muscle tension
by watching visual feedback or hearing auditory feedback. With the aid of the therapist,
the subject is then thought to relax the muscles that are diagnosed as tense and to
sense the difference between tension and relaxation,
Electroencephalogram biofeedback (EEG)
Like the heart and muscles, the brain also produces electrical impulses. An EEG is
recorded by applying electrodes to designated points on the scalp, which monitor
electrical activity close to the surface of the brain. The human brain produces different
electrical rhythms during various states of consciousness. These brain waves are
grouped and characterized by oscillations per second and amplitude.
EEG Training or Neurofeedback
The goal of neurofeedback is to teach learners to modify their EEG. There are many
applications of EEG training. One of these includes teaching the learner to maintain a
relaxed, alert, and focused mental state while carrying out cognitive tasks. Another
application of EEG training includes teaching the learner to increase slower-frequency
brainwaves to achieve deeper levels of psycho physiological relaxation or to access
calmer mental states. Other applications use EEG training to treat such disorders as
depression, anxiety, epilepsy, sleep disorders, fibromyalgia, pain, alcoholism, and other
addictions. EEG training is also used in the rehabilitation of brain injury and stroke. In
neurofeedback training, surface sensors are placed on selected areas of the head and
ears. The number and location of these sensors is determined by the specific application
and goal of the EEG training.
Temperature biofeedback:
Temperature biofeedback measures finger temperature by
attaching a sensor (called a thermister) to the fingertip. When an individual is stressed,
blood flow to the extremities is reduced, resulting in lower hand temperature. Finger
temperature can be measured using computer-based systems, or small hand-held
thermometers costing less than a dollar .
Temperature Training: The goal of temperature training is to teach the learner to
warm his or her peripheral extremities. While core temperature is 98.6ºF (37.0ºC), skin
temperature is much lower, ranging from 75-95ºF. In order to raise skin temperature,
one must relax skeletal muscles as well as the muscles within the walls of the blood
vessels. This latter effect is believed to result in better blood flow to the skin and,
therefore, a rise in skin temperature. A thermal sensor, called a thermistor, is taped to
the skin, usually on the palmer surface of one of the fingers. The temperature of the
skin changes the resistance of the thermistor, thereby altering the electrical signal in
proportion to the temperature.