STUDIES OF CEREBEAL FUNCTION IN LEARNING 



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extends as a diagonal incision from the level of the thalamico-mamillary tract 

 to the frontal pole, destroying all of the cortex of the dorsal convexity and 

 extending over the superior part of the orbital surface. The caudate nucleus 

 is completely destroyed from the level of the anterior commissure to its 

 posterior margin. The thalamus is invaded at the level of the anterior and 

 lateral nuclei. Left hemisphere : The lesion to the cortex is similar to that 

 on the right, but does not extend so far laterad. The posterior part of the 

 caudate nucleus is destroyed, as on the right. The anterior and lateral 

 thalamic nuclei are destroyed. 



Fig. 7. - Extent of the lesions in No. 19 Arranged as in fig. 5. 



No, 19. Large adult male. — The frontal lobes were transected and the 

 caudate nuclei cauterized. Training in brightness discrimination was begun 

 ten days after operation. The habit was formed in 130 trials with errors 

 in successive tens of trials distributed as follows: — 



6:6:2:5:5:2:1:3:1:1:0:1:1:0:0:0. 



Extent of lesions (fig. 7). — The dorsal convexity of both hemispheres was 

 destroyed from the level of the thalamus to the frontal pole. The orbital 

 surfaces and olfactory tracts were not injured. The lateral portion of the 

 right caudate nucleus was destroyed from the level of the knee of the corpus 

 callosum to its posterior limit. The left nucleus was uninjured. 



