Electrical Thinking

In a darkened room at the University of Jena, Germany, Professor Hans Berger felt the forehead of his assistant carefully. Finding a proper spot, he punctured the skin, shoved a small silver needle through the interstices of the skull until the tip rested against the outer covering of the cerebral cortex. In the back of the head, he inserted a similar needle, attached a galvanometer to both. Then he stroked the assistant's arm with a glass rod, gave him arithmetic problems to solve.

Dr. Berger was looking for electrical brain waves. Although for 50 years similar experiments have been performed on animals, this was the first time a man had been subjected to such difficult research. From such experiments Dr. George Washington Crile of Cleveland developed his bipolar theory: the brain is the positive pole, the liver the negative pole of the body (TIME, Nov. 5, 1923, Aug. 30, 1926).

In the last issue of Der Medizinische Welt, leading German medical journal, Dr. Berger published the results of his experiment. The Elektrenkephalogramm, as Professor Berger called the galvanometer record, showed plainly that the brain produced electricity. Comparison of figures seemed to indicate that electric current decreases as mental activity increases. Dr. Berger distinguished two types of waves, alpha and beta. The alpha waves represented the normal electricity output of an organism when not highly stimulated. The current generated was .2 microvolt. Beta waves represented the brain's electricity production when the subject was stroked by the glass rod, told to figure out an arithmetic problem. The galvanometer at this time registered .1 microvolt.

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