604 



SCIENCE 



[Vol. LV, No. 1432 



In the convolutions on the surface of the 

 brain are certain small aggregations of motor 

 nerve cells in the gray matter called "motor 

 centers." On being stimulated by an electric 

 current, these cells produce motion, each cen- 

 ter in one definite portion of the body, and 

 never in any other part. These motor centers 

 are all grouped around the fissure of Rolando, 

 which runs obliquely downward and forward 

 above the ear. This, and another deep furrow 

 called the fissure of Sylvius, are always readily 

 identified in the lower animals. The motor 

 centers for movements of the leg, arm, face, 

 fingers, etc., in the brains of the lower animals, 

 up to the anthropoid ape, have been exactly 

 mapped out by experiments on animals. In 

 the human brain the location of the correspond- 

 ing motor centers is a duplicate of those in the 

 brains of animals. Let me relate some striking 

 cases to confirm this statement. 



A young woman with epilepsy, in whom the 

 attacks were constantly increasing in frequency 

 and violence, insisted that her attacks always 

 began in her left thumb, then spread to the 

 hand, then to the arm, followed by unconscious- 

 ness and violent convulsions all over the body. 

 Careful observation for two weeks in hospital 

 confirmed her statements that the fits always 

 did begin in this left thumb. If, then, I could 

 prevent the fit from beginning in this thumb, 

 so I reasoned, it might be that I could prevent 

 the entire attack. Just as, in a row of bricks 

 standing on end, if I can prevent the first one 

 from falling, none of the others will fall. 



The possibility of the exact localization of 

 the little cube of gray matter on the surface of 

 the brain, dominating all the muscles of the 

 thumb, was the key to the whole operation. 

 This localization of the thumb center had been 

 made absolutely by experiments on the brains 

 of animals. Accordingly, I opened her skull, 

 identified the spot corresponding to the thumb 

 center (i. e., the great toe of the fore foot) in 

 animals, and cut out a small cube less than an 

 inch on each side. 



Next, note the fact' that there are nine muscles 

 moving the thumb, some in the ball of the 

 thumb, some between the thumb and the fore- 

 finger, some extending up the front of the fore- 

 arm, and some up the back of the forearm. 



both of the latter reaching nearly to the elbow. 

 Some flex and some extend the thumb, some 

 separate it from the other fingers, and by one 

 we can make the thumb touch each of the other 

 four fingers. This is the motion which differ- 

 entiates the human "hand" from the animal 

 fore foot. 



When this patient awoke from the ether, 

 every one of these nine muscles was paralyzed 

 and in not a single additional muscle was mo- 

 tion affected. The human brain center and 

 the animal brain center for the thumb were 

 proved to be precisely identical. My hopes 

 were justified. Her epileptic attacks, which 

 had occurred almost daily, recurred only about 

 once in a year. In a few months she even re- 

 gained full control over this thumbi 



Two other later similar cases still further 

 confirmed this wonderfully exact localization. 

 A fourth brain ease : In 1888, I reported 

 my first three cases of modern surgery of the 

 brain. Attending the meeting of the American 

 Surgical Association in Washington, when I 

 read this paper, was Sir David Terrier of 

 London. He had contributed very largely to 

 this then wholly new mapping of the brain 

 centers which control motion. In one case, I 

 described how I had stimulated a certain small, 

 definite motor area in the brain of my patien^ 

 by the battery,- and described the resulting 

 movements of the arm at the shoulder. Ferrier 

 afterwards said to me, "I could hardly restrain 

 myself from leaping to my feet, for this was 

 the very first demonstration on the human 

 brain of the exact identity of my own localiza- 

 tion of this very center in animals." 



A fifth brain case : A midshipman in the 

 United States Naval Academy at Annapolis, 

 in 1902. I saw him three days after his acci- 

 dent. All the history I obtained was that he 

 had been injured in a foot-ball game, had been 

 unconscious for half an hour, and since then 

 had complained bitterly of headache, which he 

 located in his forehead. He was almost coma- 

 tose, his pulse was only 52. There was no 

 fracture of the skull. Soon after the accident, 

 he developed local convulsions — note this care- 



- Tlie braiii tissue itself is wholly devoid of 

 sensation and can feel no pain. 



