1052 CORTICAL MOTOR REGION IN MAN. [BOOK in. 



plications due to the subsidiary effects of the operation, and it 

 may be doubted whether in any of the recorded experiments the 

 animal has been allowed to live a sufficient time for these sub- 

 sidiary events to have cleared away, leaving only what we have 

 called the ' deficiency ' phenomena, due to the loss of the cortical 

 area alone. On the other hand it must be remembered that the 

 movements of the monkey are more intricate in origin, more 

 ' skilled ' than those of the dog ; and it may be that differences 

 in the characters of movements determine the possibility of their 

 recovery. In illustration of this we may quote the experience 

 that, after the removal of the arm area in the monkey, a certain 

 awkwardness in the movements of the thumb is one of the last 

 effects of the operation. 



659. Before we proceed however any further in the dis- 

 cussion, it will be of advantage to turn aside to what is known 

 concerning the cortical motor region in man. As we have already 

 said, theoretical considerations lead us to believe that the cortical 

 motor region in man is disposed in accordance with the plan of 

 the anthropoid ape as ascertained experimentally, but with the 

 differentiation carried still further ; and the few cases of experi- 

 mental stimulation of the human cortex support this view. Our 

 chief knowledge in this matter is derived from the study of 

 disease ; and in this, the advantages of dealing with one of 

 ourselves are largely counterbalanced by the disadvantages due 

 to disease being so often anatomically diffuse and physiologically 

 changeful and progressive. 



We said above that during experiments on animals stimulation 

 of any part of the motor region may under abnormal 'conditions 

 lead to general epileptiform convulsions. Now clinical study has 

 shewn that in man certain kinds of epileptic attacks are of 

 similar cortical origin. In these cases it has been observed that 

 the attack begins in a particular movement, by contractions of 

 particular muscles, or of the muscles of a particular region of the 

 body, of the hand, foot, toe, thumb, &c., and then spreads in a 

 definite order or ' march ' over the muscles of other regions until 

 the whole body is involved. When in an experiment on an 

 animal epileptiform convulsions supervene, they similarly start 

 from the region of the body, the motor area of which is beneath 

 the electrodes at the time, and similarly spread by a definite 

 ' march ' over the whole body. Hence in the human epileptiform 

 attacks of which we are speaking, it has been inferred that the 

 immediate exciting cause of the attack is to be sought in events 

 taking place in that part of the cortex which serves as the area 

 for the movement which ushers in the attack. Further inquiry 

 has not only confirmed this view, but has also shewn that the 

 topography of the cortical areas in man, as thus determined, 

 very closely follows that of the monkey. 



Other diseases of the cortex have been marked, among other 



