TECHNOLOGY AND MEDICINE—LION 405 
localize or coordinate certain parts of the brain with some mental or 
physical anomalies. A considerable increase in the sensitivity of the 
instruments used in electroencephalography is not possible, however. 
The magnitude of brain action potentials is close to the noise level 
which it is impossible to overcome. 
It is to be expected that further research on electric nerve action 
potentials in connection with other organs, glands, and so on, will 
evolve diagnostic methods which are perhaps of even greater im- 
portance in general medicine or in psychiatry than the ones we already 
have. The difficulties are great; what we measure is largely a super- 
imposition of many different electrical signals. Sometimes the 
development of special experimental techniques is required to elim- 
inate those signals which are not desired and to record undistorted 
the signals characteristic of the process under study. One difficulty 
here is the lack of a proper explanation of the fundamental process 
of propagation of nerve action potentials. The velocity with which 
an impulse travels along a nerve is of the order of one meter a second. 
This velocity is too fast for propagation to be achieved by purely 
chemical means; it is too slow to be the result of a purely electrical 
phenomenon. 
The problem of physical diagnosis is frequently that of getting 
some information about processes going on inside the body from 
measurements on the body surface. Besides mechanical, thermal, or 
optical properties of the skin, its electrical properties can also be used 
diagnostically. From simple electrical resistance measurements of 
the skin one can get indications of the activity of the sympathetic 
nervous system and of emotional reactions of the person under obser- 
vation. An instrument used for this purpose is known in medicine 
as a psycho-galvanic reflex meter and has attained wide publicity as 
the lie detector. It is very likely that this instrument, in the hands 
of an experienced psychologist, can uncover the deeper cause of many 
diseases and, perhaps, can open up a new physical experimental 
approach to psychological and neurological studies which, in the past, 
have been based solely upon theory. 
THERAPEUTIC APPLICATIONS 
Many persons also expect the field of physical therapy to show a 
development as rapid as that which has taken place in physical diag- 
nosis. The situation with respect to the search for physical means of 
healing and curing is, however, somewhat different from that of diag- 
nosis. In his popular book about medicine? Dr. Carl Binger charac- 
terizes research in therapeutics with the words, 
Like happiness, a cure is seldom found by searching for it. Some cures are the 
logical outgrowth of deep scientific understanding, others are stumbled upon by 
2 The Doctor’s Job, p. 149. W.W. Norton & Co., Inc., New York, 1945. 
