DYNAMOS IN BRAIN

Thames Star, Volume LXVI, Issue 19622, 1 February 1936, Page 4

DYNAMOS IN BRAIN

DISCOVERY OF SIX. RESEARCH IN AMERICA. Penetration of the lower depths of the cerebral cortex, topmost layer of the brain and seat of higher intefligence, which reveals for the first time the existence of a separate electrical dynamo in each of the six individual layers of that no-man’s land of mind and matter, was reported before the National Academy of Science meeting at the University of Virginia, says the New York Times. It had been previously demonstrated in some experiments at Harvard and other research centres that the brain sends out electrical signals which change with its various states of activity and repose, but which continue even during sleep. These brain currents, however, referred to the brain as a whole. Now for the first time the scientists were told of new measuring rods of brain electricity which make it possible to measure the electrical activity of the separate layers of the cerebral cortex of the monkey.

The report was presented by Dr. J. D. Dusser de Barenne and Dr. W. S. M'Culloch, of Yale University. In their pioneer experiments, which promise to shed further light on the mystery of cerebral functioning, Drs. de Barenne and M'Culloch first measured the electrical “action potentials”* of the animal’s brain cortex while under anaesthesia. They then proceeded by a new technique to remove layer after layer as one would remove the layers of an onion, and to measure the electrical activity that was left in the remaining layers. In this manner the electrical potentials of the various layers were determined for the first time.

The peeling of the brain layers is accomplished by the application of heat for very brief periods. The greater the heat and the duration of the period of its application the more layers are removed. When the entire six layers were treated by the heat no electrical activity was lefifc in the particular cortical area, the Yale scientists reported. The cortex of the monkey, the report stated, is one and a-half millimetres thick, and each of the six layers is but two-tenths of a millimetre.

By applying a temperature of 65 degrees centigrade for three seconds, the Yale men found, the two outer layers of the cortical area ceased their electrical activity. Seventy degrees for three seconds eliminated the electrical signals in the three outer layers. Seventy degrees heat applied for four seconds silenced the dynamo in four layers, while eighty degrees centrigrade applied for five seconds eliminated the electrical signals in all the si# layers.