CEREBRAL FUNCTION IN THE RAT 



97 



The curves of the learning and retention tests are given in 

 figure 9. It is evident that very much less time was required 

 for the solution of the problem at the beginning of the retention 

 tests than at the beginning of learning, but that improvement 

 was relatively slower. Apparently the plane retained a certain 

 stimulatory value, much like that which it acquires in the early 

 stages of learning, but did not at first call out the appropriate 

 reactions for getting food. 



FIG. 9. RATE OF IMPROVEMENT IN TRAINING AND RETENTION TESTS FOR 



EXPERIMENT 21 

 Arranged as figure 8 



Lesions (plate III, fig. 21). Right hemisphere. There is a 

 transverse lesion extending from just behind the knee of the 

 corpus callosum laterad to the cortex and diagonally ventrad 

 through the base of the olfactory bulb. The greater part of the 

 mesial face of the frontal pole is intact but there is a probable 

 destruction of all the antero-lateral area. 



Left hemisphere. There is a transverse lesion extending from 

 the anterior horn of the lateral ventricle along the forceps of 



PSYCHOBIOLOGY, VOL. I, NO. 2 



