IT) 



ON THE MOTOR FUNCTIONS OF THE CEREBRAL 

 CORTEX OF THE CAT 1 



JOSEPH DUERSON STOUT 



From the Laboratory of Physiology of the George Washington University 



The results of the early experiments to determine the locali- 

 zation of the cerebral motor areas, by means of electrical stimu- 

 lation were far from consistent. Some of the discrepancies may 

 be accounted for on the ground of differences of experimental 

 methods, but that other factors may be present has generally 

 been lost sight of. Franz has recently shown that when a num- 

 ber of hemispheres are investigated by the same stimulation 

 method considerable variations are discovered! These varia- 

 tions are chiefly: (1) Differences in the absolute amount of thb 

 stimulable areas; and (2) differences in the relative extents of 

 the stimulable areas for individual segments (for the fore and 

 hind limbs which he investigated). In the more highly devel- 

 oped brain of the monkey, on which he worked, and in man, 

 such variations are, he has shown, indicated by the activities of 

 the individual animals. In those animals in which the nervous 

 system, and especially the cerebrum is simple, the routine and 

 partly unvarying nature of the reactions suggests that there 

 may be less variation in motor cerebral control. Franz has 

 demonstrated what others had previously suggested, that the 

 greater complexity of the brain in higher animals is associated 

 with a greater variation in motor control. 



1 The investigation of the motor areas of the cat's brain was made because 

 this animal is being generally utilized in experiments on the nervous system (cf . 

 especially Sherrington's studies of reflexes), because of the ease with which it 

 can be handled, because its general behavior is less complex than that of the 

 monkey, and more variable than that of the rabbit and other rodents, because 

 this animal has been used in a number of previous experiments and its capacity 

 of learning (the possibility of motor adjustments) has been investigated, and 

 because the motor area of the animal has not been carefully mapped out. 



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P8YCHOBIOLOGY, VOL I, NO. 3 



