270 



ORIGINAL ARTICLES AND CLINICAL CASES 



were required for learning, with errors in successive tens of trials distributed 

 as follows : — ■ 



7:7:4:2:1:1:0:1:0:0:0:0:0. 



The frontal lobes were transected and the caudate nuclei cauterized. The 

 animal was stuporous for the first day after operation, but on the second day 

 was in fair condition and reacted promptly to the problem box, although 

 tending to rotate to the left. On this day he made four errors in twenty 

 trials, but the errors were obviously due to failure to compensate for the 

 motor difficulty and his behaviour in the discrimination compartment clearly 

 indicated discrimination. On the following and later days he made no errors. 



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



2:2:0:0:0:0. 



Fig. 10. — Extent of the lesions in No. 22. Arranged as in fig. 5. 



Extent of lesions (fig. 10). — Eight hemisphere. The lesion extends from 

 the level of the thalamus to the base of the olfactory bulb, separating all of the 

 cortex above this plane from the underlying structures. The cortex of the 

 orbital surface was destroyed by the cautery. The lateral portion of the 

 caudate nucleus is destroyed by a lesion which embraces the full width of 

 the nucleus at the level of the anterior commissure and grows narrower 

 cephahul and caudad to this level. Left hemisphere : The incision extends 



