2o8 BRAINS OF RATS AND MEN 



habit formation brought to light by the experimental 

 procedures adopted. The normal rat's total behavior 

 under other conditions may involve cortical activi- 

 ties of quite different sorts with more precise locali- 

 zation in space of the nervous connections involved 

 in both the learning process and the stabilized mne- 

 monic patterns. 



In view of what we know of cortical function in 

 animals higher than rats it may safely be assumed 

 that an act, whether of learning or any other, in which 

 the cortex participates is a very different act from one 

 performed wholly by the subcortical apparatus, even 

 though under some simplified experimental conditions 

 the overt behavior may seem similar in the two cases. 



The presence of uninjured cerebral cortex may ac- 

 tually retard learning a very simple habit by reason 

 of the complication of the process through intercur- 

 rent cortical associations from other sensory fields. 

 But when such cortex does participate the act is a 

 better act, at least from the standpoint of its adapta- 

 bility to changed conditions in the future where this 

 type of experience is a factor in a new adjustment, as 

 Professor Carr has called to my attention. He says, 

 *'The cortex not only enables an organism to acquire 

 a response to a given object, but a response adapted 

 to that object in a given situation." The animal may 

 thereafter vary its response to this object according to 

 the external environment in which it occurs and the 

 internal condition of the body at the moment. This 



