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January 10, 1931


JAMA. 1931;96(2):116. doi:10.1001/jama.1931.02720280034011

Until recently, textbooks of physiology have had little to say regarding the metabolism of the nervous system. One cannot penetrate far into the domain of muscle function before being brought face to face with problems of energy exchange. Consideration of muscular contraction inevitably is concerned with the production of work and heat; and such a process in turn involves the production of carbon dioxide and the utilization of oxygen. Nervous excitement and mental activity also may increase metabolism; but, as Mitchell1 has pointed out, no measurements of this increase have effectively eliminated the muscular contractions that accompany nervous activity. It is certain that most of the increase in metabolism, if any, that occurs during mental work is caused by contractions of skeletal muscles. They are active in maintaining a somewhat rigid posture of the body and in other ways, under these conditions. When complete muscular relaxation is maintained, Mitchell