EEG Article

HIGH in the Himalayas, the monks of Tibet have practiced a remarkable initia-tion ritual for thousands of years. On the coldest days of winter, candidates go to spend the night by frozen lakes clad only in their thin orange robes. Symbolic white robes are clipped into the icy water and draped around their naked bodies. The number of robes a candidate can melt in a single night symbolizes the level of his spiritual achievement.

Eastern mystical teachings have a formula that anyone can follow to achieve such spectacular body control years devoted to meditation, complex visualizations, and sex-ual continence.

Characteristically, however, Western tech-nology is encroaching on this formerly East-ern monopoly with electronic devices that demand neither sacrifice nor discomfort.

Elmer Green at the Menninger Foundation in Topeka, Kansas, has taught subjects to lower the temperature of their hands ten degrees by using a simple device which in-dicates body temperature increases by movement of a meter. Subjects were told to move the indicator up-scale and hold it

there. Most subjects could, in a small amount of time, learn to influence the temperature of different parts of their bodies by using the information transmitted by the electronic measurement circuit.

Similar to the monks, his subjects were using their minds to generate heat energy at a particular area of their body. Ten degrees is a long way from melting frozen robes but scientists arc finding that people can influence all kinds of body processes, hitherto believed beyond the range of con-scious control.

Closing the Loop. Traditionally, Western medicine considered certain regulatory time-

Editor's Note: In response to many requests from readers for articles 01 alpha brain waves, we are presenting two stories. This month, we cover the general principles of biofeedback training as well as the various types of waveforms generated by the brain. Next month, we will have an alpha-wave monitor construction project for those who want to do some experimenting.

tions of the body such us skin temperature and heart rate as outside the domain of will-ful control. This assumption seems to have helped shape the self-concept most of us have of being at the mercy of our involuntary nervous system. The self-regulating nervous system is. of course, a necessity, for imagine the effort of controlling all the specialized muscles involved in breathing or digesting. We could, you might say, speed up our heart rate by physical exertion such as fast breathing, but this is not direct control of the autonomic nervous system.

Certain recent experiments have now caused scientists to take a new look at this old assumption. Some visceral organs, it was discovered, could be eventually controlled by the mind if special conditions were first set up. What was needed was a special signal or stimulus, such as sound or light. which would follow the activity of the body function to be controlled. By observing the "feedback" signal, people could actually in-teract with a particular body function through the monitor. The monitor or bio-feedback mechanism serves in a sense as an interpreter between the mind and the so-called "automatic" mind.

The principle is similar to the way you learn to throw a ball. You feel your arm move, see where the ball went and correct your arm movement the next time. In a similar way, an electronic instrument can detect small internal changes in such processes as blood flow or brain-wave patterns of which you may not be consciously aware. By showing you these changes, the device can help you to recognize the cues and learn control. What is even better is that with practice, control can be developed so that the instrument is no longer needed.

The Body Electronic. To understand fully the range of the feedback principle, it is helpful to examine the source of the feed-back signal.

Bio-potentials, tiny voltages present in all living organisms, are caused in man by the activity of nervous system sensors, muscles, or nerves. All bio-potentials originate at the cellular level, but the measurement of any one signal is related to a spe-cific physiological subsystem. Thus, the elec-trocardiogram(EKG) is a recording of the electrical activity of the heart, the electroencephalogram (EEG) of the voltages in the brain, the electromyograrn (EMG) of the activity of the muscles.

Detecting the brain-wave biopotentials is greatly complicated by the minute signal voltages, high level of external interference (noise and hum) and high impedance values of the body. For example, the magnitudes of the signals measured on the scalp typically vary from ten to a hundred mil-lionths of a volt (10-100 microvolts) peak-to-peak. To top it off, in residential areas, stray 60-cycle fields from power lines surround the body. Such fields may reach values of 10 volts, or a million times stronger.