STUDIES OF CEREBRAL FUNCTION IN LEARNING 



269 



degrees to the left. Fig. 14 shows some of her simpler paths in traversing the 

 problem box. 



Post-operative retention tests ; errors in successive tens of trials on con- 

 secutive days. : — 



1:1:4:3:0:1:0:1:1:0:0. 



Extent of lesions (fig. 9.) — All of the cortex of both hemispheres from 

 the level of the thalamus to the base of the olfactory bulb is destroyed. The 

 right caudate nucleus is completely destroyed except for a small antero-medial 

 region laterad to the forceps of the corpus callosum. The left caudate nucleus 



Fig. 9. — Extent of the lesions in No. 21. Arranged as in fig. 5. 



has a superficial transverse lesion at the level of the anterior commissure. 

 The right anterior thalamic nucleus is invaded. 



After destruction of the stimulable cortex and severe injury to 

 both caudate nuclei, resulting in marked motor disorganization, this 

 animal gave certain evidence of retention of the habit of visual dis- 

 crimination. 



No. 22. Large male. — Trained in visual discrimination. Eighty trials 



