CEREBEAL FUNCTION IN LEARNING 87 



For comparison with this work two animals have been trained 

 on the more complicated double-platform box after destruction 

 of the frontal poles of the cerebrum. Brief descriptions of their 

 records follow. 



Number 16. Large female, about 200 days old. The frontal lobes 

 were destroyed by transverse sections from trephine openings just back 

 of the fronto-parietal suture. Recovery was normal without behavior 

 disturbances. Training was begun 43 days after operation. Learning 

 progressed normally. 



Number of trials required for learning 90 



Per cent of total cortex destroyed 15 . 5 



Lesion: Plate II, figure 16 (17). Both frontal poles were completely 

 severed from the remaining cortex by a transverse section extending 



FIG. 7. THE TOTAL EXTENT OF THE LESIONS IN ANIMALS WHOSE RECORDS ARE 



SHOWN IN FIGURE 6 



from a point above the knee of the corpus callosum diagonally cephalad 

 to the olfactory tracts. The cerebral nuclei were uninjured. 



Number 17. Large female, about 200 days old. The operation was 

 similar to that of number 16. The animal recovered rather slowly and 

 remained emaciated throughout the experiment. Training was begun 

 43 days after the operation. Reactions were slow and deliberate. The 

 animal gave evidence of rather rapid learning during the first 40 trials, 

 then developed a stereotyped reaction to the second platform, making 

 sometimes as many as 100 trips to this before going to the first. After 

 200 trials she made a number of correct reactions, but never succeeded 

 in meeting the requirements of the problem. From the 50th trial on 

 she gave evidence of illness, and by the 250th trial she had become so 

 weak that it seemed best to drop training. 



Number of trials required for learning 250+ 



Per cent of total cortex destroyed 15.5 



