CEREBRAL FUNCTION IN THE RAT 129 



The majority of writers agree that there is a frontal field, 

 variously located in the region I which has not the characteristics 

 of the motor areas, but no statements are made as to its rela- 

 tion to the frontal lobes of higher mammals. The stimulation 

 experiments which we have carried out indicate that even the 

 extreme pole of the cortex is excitable, that there is no silent 

 area corresponding to the frontal lobes of higher mammals, but 

 the small size of the brain and the difficulty of preventing some 

 spreading of the current would make it difficult to detect such 

 an area if it existed. 



There is no experimental evidence concerning the function of 

 these fields, although a part has been interpreted as motor, 



FIG. 15. THE CHIEF CYTOARCHITECTURAL AREAS OF THE BRAIN OF THE MOUSE. 



AFTER ISENSCHMID 



another as sensori-motor. According^ to Isenschmid, who has 

 summarized the literature of this subject the area described as 

 motor differs considerably in the descriptions of different authors. 



Upon purely histological grounds Cajal includes an area extend- 

 ing over a, a\, and b, in figure 15. Dollken (8) includes the 

 areas I, k, a, ai, 6, and the anterior portions of q and d Brod- 

 mann (9) includes k and a part of field I. 



Without physiological verification conclusions as to the func- 

 tion of histologically differentiated parts can have little value. 

 The stimulable area has been found to correspond most closely 

 to the anatomical field described by Dollken. The excitable 

 areas thus far determined are shown in figure 16. They em- 



PSTCHOBIOLOGT, VOL. I, NO. 2 



