STUDIES OF CEREBRAL FUNCTION IN LEARNING 



•273 



fourth day she still rotated but was able to find her way through the box by 

 keeping near the partitions, and made only one error in ten trials. On the 

 following day she developed pronounced fear reactions and climbed out of the 

 training box more than one hundred times. She was finally induced to 

 make ten trials, but made six errors. Training was discontinued for five days. 

 When she was next tested the fear had disappeared and she showed perfect 

 discrimination. 



Post-operative retention tests ; errors in successive tens of trials : — 



1:6:0:1:0:0:0. 



Fig. 12. — Extent of the lesions in No. 24. Arranged as in fig. 5. 



Extent of lesions (fig. 13). — Right hemisphere: The lesion to the cortex 

 begins at the level of the commissura habenulae and extends to the base of the 

 olfactory bulb, including all of the motor cortex except a part of the hind leg 

 area. The cautery passed throughout the length of the caudate nucleus and 

 the entire nucleus is degenerated. Left hemisphere : The lesion to the cortex 

 is similar to that on the right, but misses the antero-lateral surface of the 

 frontal pole, and does not extend so far over the orbital surface. The caudate 

 nucleus is entirely degenerated. 



Practically the entire stimulable cortex and both caudate nuclei 



