184 JOSEPH DUERSON STOUT 



LOCALIZATION AND LIMITATION OF THE MOTOR AREA 



The first series of experiments was conducted with the object 

 of locating the boundaries of the motor field of the cat's cerebral 

 cortex. For this purpose twelve animals gave results of com- 

 parative value, although the details for all animals are not given 

 in the present paper. All cases are omitted in which the experi- 

 ments were not completed to the desired point, but the results in 

 these omitted cases do not differ, except in minor detail, from 

 those that are recorded here. The results indicate that the 

 motor area is confined laterally to that portion of the cortical 

 surface between the two coronal fissures and the median line. 

 It extends posteriorly to the , anterior extremity of the fissura 

 lateralis, and anteriorly to a line about 0.5 cm. above the upper 

 extremity of the olfactory lobe. It occupies both banks of the 

 crucial sulcus, and, anteriorly to the crucial sulcus, it extends 

 over to and upon the median surface of the hemisphere about 

 0.5 cm. The region thus marked off is fairly constant in different 

 animals, and the stimulation of similarly located areas of it in 

 the successive animals led to the production of movements 

 which, in their general nature, are similar. These motor reac- 

 tions are, for the purpose of study, divided into four groups, 

 according to the portions of the body involved, and the location 

 on the cortex of the points from which they were initiated was 

 mapped out. .These groups are (1) hind limb, (2) trunk and 

 tail, (3) fore limb, and (4) head and neck. 



Total extents of motor area 



Cat 8 was the first one to offer sufficient results to be satis- 

 factorily considered in this classification. The motor field of 

 the right hemisphere extended from the fissura lateralis to a line 

 0.5 cm. above the superior margin of the olfactory lobe, and 

 from a line 0.5 cm. from the median line outward, almost to the 

 fissura coronalis. The movements of the hind limb were ob- 

 tained from stimulation of the whole of this area, with the ex- 

 ception of a narrow strip on the outer side and a small area 

 anteriorly. Movements of the trunk and tail were few in num- 



