EEG correlates of attention in humans.

Until recently, scientists have been extremely critical of reports claiming that Yogis have learned to deliberately regulate their heartbeat, body temperature, and other internal body processes normally considered to be of an involuntary nature. Largely ignored also were reports that some subjects in deep states of hypnosis (an altered state of consciousness) could by suggestion be made to effect changes of a physiological nature normally considered not to be under voluntary control: For example, the raising of blisters and control of heart rate.