EEG or Electroencephalography

EEG in Biofeedback: The electroencephalograph (EEG) monitors the brainwave activity from sensors placed on the scalp. Applications for EEG feedback are currently being developed. These include epilepsy, hyperactivity and attention deficit disorder, alcohol / chemical dependency and other addictive disorders, traumatic brain injury, sleep onset disorders and insomnia.

EEG History: The presence of electrical current in the brain was discovered by an English physician, Richard Caton, in 1875. It was not until 1924 that Hans Berger, a German neurologist, used his ordinary radio equipment to amplify the brain’s electrical activity so that he could record it on graph paper. Berger noticed that rhythmic changes (brain waves) varied with the individual’s state of consciousness.

The various regions of the brain do not emit the same brain wave frequency simultaneously. An EEG electrode placed on the scalp would pick up many waves with different characteristics. This has presented a great deal of difficulty to researchers trying to interpret the large amount of data they receive from even one EEG recording.Brain waves have been categorized into four basic groups: Alpha, Beta, Theta, & Delta waves. Although none of these waves is ever emitted alone, the state of consciousness of the individual may make one frequency more pronounced than the others.

EEG wave groups:

BETA. The electrical activity of the brain is varying within the range of 14 – 26 times per second ( or Hz). A different name has been given to frequencies above 26 Hz but it is more usual to refer to these as fast beta waves. Beta is the usual waking rhythm of the brain associated with active thinking, active attention, focus on the outside world or solving concrete problems.

BETA *writers comment. The EEG trace is usually taken in a hospital or a laboratory setting by men in white coats in front of daunting apparatus. Testing in such a situation, most people will show a panic response and this is the real meaning of a high level beta. A machine which analyses the EEG signal into its separate components easily differentiates between a calm person solving a problem in mental arithmetic and a person who is reacting to the test ambience.

ALPHA. The rate of change lies between 8 and 13 Hz. Alpha waves have been thought to indicate both a relaxed awareness and also inattention. A receptive mind.

ALPHA *writers comment. Alpha is the most prominent rhythm in the whole realm of brain activity and possibly covers a greater range than has been previously accepted. You can regularly see a peak in the beta range as high as 20 Hz, which has the characteristics of an alpha state rather than a beta, and the setting in which such a response appears also leads to the same conclusion. Again, we very often see a response at 75 Hz which appears in an ‘alpha’ setting. Most subjects produce some alpha with the eyes closed and this is why it has been claimed that it is nothing but a waiting or scanning pattern produced by the visual centers of the brain. It is reduced or eliminated by opening the eyes, by hearing unfamiliar sounds, by anxiety or mental concentration. Albert Einstein could solve complex mathematical problems while remaining in the alpha state, though our work suggests that other frequencies, beta and theta would also have been present. Alpha alone seems to indicate an empty mind rather than a relaxed one, a mindless state rather than a passive one, and requires the presence of other frequencies, beta and theta before the usual description of alpha becomes true. Alpha, per se, is not associated with inwardly directed attention, relaxed awareness, or feelings of well being. In ‘alpha’ training we are not in fact primarily interested in learning to produce an alpha rhythm ( despite the immense amount that has been written about it ) rather what we are interested in experiencing is the particular calm detached state which happens to be accompanied by the alpha rhythm. Training to produce alpha on a biofeedback machine might therefore produce alpha without the sidebands beta and theta and therefore be experienced as a mindless and rather boring state. However, if the alpha state was produced by a meditative exercise, a Sufi teaching story, or by contact with a master, then there will be a long term effect on the subject’s alpha because he or she has changed as a result of the experience.

THETA. Theta waves lie within the range of 4 to 7 Hz. Theta appears as consciousness slips toward drowsiness. Theta has been associated with access to unconscious material, creative inspiration and deep meditation.

THETA *writers comment. Theta is usually accompanied by other frequencies and seems rather to be related to level of arousal. We know that healers and experienced meditators have an alpha which gradually lowers in frequency over long periods of time. The large dominant peak of the 10 to 20 year meditator will almost certainly be found to be around 7 Hz in the so called theta band.

DELTA. Delta waves lie within the range of 1/2 to 4 Hz. Delta waves are primarily associated with deep sleep, and in the waking state, was thought to indicate physical defects in the brain.

DELTA *writers comment. It is very easy to confuse artifact signals caused by the large muscles of the neck and jaw with the genuine delta response. This is because the muscles are near the surface of the skin and produce large signals whereas the signal which is of interest originates deep in the brain and is severely attenuated in passing through the skull. Nevertheless, with an instant analysis EEG, it is very easy to see when the response is caused by excessive movement.

EEG History, taken from BIOFEEDBACK Methods and Procedures in clinical practice ( 1977) written by George D Fuller, Ph.D.

EEG Wave Groups, taken from The Meaning of EEg *published by the publications div. of Audio Ltd. London

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