34 



K. S. LASHLEY AND L. E. WILEY 



We have attempted to analyze the data on the basis of 

 specific subcortical injuries, but have not been able to dis- 

 cover any significant relations. In our data it is usually 

 possible to match any case with a subcortical injury with 

 another having only a similar cortical destruction. It seems 

 entirely a matter of chance as to which member of such pairs 

 has the worse training record. We have not been able to 

 find indications of specific effects upon maze learning of 

 any lesions in the corpora striata or thalamus within our 

 series of cases. 6 It seems quite certain that the correlation 

 between extent of cortical injury and the degree of retarda- 

 tion is not due to the inclusion in the series of animals with 

 subcortical lesions. 



TABLE 16 



Comparison of the correlations between extent of lesion and errors in learning 



for all cases and for cases without significant subcortical lesions. Maze V 



The relative effects of symmetrical and asymmetrical lesions 

 in producing retardation of learning 



In order to test the influence of corresponding areas of the 

 two hemispheres, we have determined the areas common to 

 the destruction in both hemispheres, as described on page 

 16, and from these have computed the correlation between 

 extent of symmetrical destruction and errors made during 

 training, using only the data on mazes I and IV, as a sample. 

 The results of this analysis were given in table 17. The cor- 

 relation for the symmetrical portions alone is the same as 

 for the total extent of lesion. That for the asymmetrical 



a The subcortical lesions are for the most part slight and unilateral. In no 

 case is there an extensive bilateral injury to any thalamic center. 



