The brain basis of a "consciousness monitor": Scientific and medical significance

Surgical patients under anesthesia can wake up unpredictably and be exposed to intense, traumatic pain. Current medical techniques cannot maintain dep th of anesthesia at a perfectly stable and safe level; the depth of unconsc iousness may change from moment to moment. Without an effective consciousne ss monitor anesthesiologists may not be able to adjust dosages in time to p rotect patients from pain. An estimated 40,000 to 200,000 midoperative awak enings may occur in the United States annually. E. R. John and coauthors pr esent the scientific basis of a practical "consciousness monitor" in two ar ticles. One article is empirical and shows widespread and consistent electr ical field changes across subjects and anesthetic agents as soon as conscio usness is lost; these changes reverse when consciousness is regained afterw ard. These findings form the basis of a surgical consciousness monitor that recently received approval from the U.S. Food and Drug Administration. Thi s may be the first practical application of research on the brain basis of consciousness. The other John article suggests theoretical explanations at three levels, a neurophysiological account of anesthesia, a neural dynamic account of conscious and unconscious states, and an integrative field theor y. Of these, the neurophysiology is the best understood. Neural dynamics is evolving rapidly, with several alternative points of view. The field theor y sketched here is the most novel and controversial. (C) 2001 Academic Pres s.