174 BRAINS OF RATS AND MEN 



those of the co-called motor cortex in the pyramidal 

 tract. The precise definition of the functions of these 

 various efferent systems is one of the major unsolved 

 problems of cerebral physiology. 



6. In what sense is there localization of function 

 in the cerebral cortex, and in particular, can specific 

 projection centers and association centers be recog- 

 nized in the rat? 



Lashley's experiments were directed very explicit- 

 ly to this general problem and to certain special 

 aspects of it to be mentioned immediately. These ex- 

 periments have brought to light some very surprising 

 conditions which are quite at variance with tradition- 

 al ideas of cortical localization. 



7. Are cortical functions which are demonstrably 

 related with the learning process localizable in par- 

 ticular areas, or is the cortex of the rat equipotential 

 in learning in all of its parts? 



Lashley is greatly impressed by the failure of his 

 experiments to reveal evidence for any relationship to 

 the learning process of specific projection centers for 

 definite sensory or motor systems except the visual 

 (and perhaps the olfactory, which was not investi- 

 gated). And he finds no physiological evidence for 

 specific association centers of any kind, except within 

 the visual field of the occipital lobes. Even here it is 

 not certain that the visual field functions in the re- 

 dintegration of habits as such, that is, in true associa- 

 tion. It may participate in the habit simply as a nee- 



