96 



BRAINS OF RATS AND MEN 



hemispheres can be removed without loss of the 

 fundamental reflexes. Such a partially decerebrated 

 pigeon will avoid objects in walking and flying and 

 possesses normal eye reflexes. Though at first it 

 cannot feed spontaneously, in the course of a few 

 weeks it may reacquire the power of feeding itself. 



CQCtex 



bijpcrstrlatum 



£J^ectostn'alum 

 mcsostripturn 

 epi'strlatum 



Fig. 19. — Cross-section through the right cerebral hemisphere of 

 the pigeon with parts of the corpus striatum named after Edinger. 



The elements of the mating reflexes and other com- 

 plex behavior patterns are seen, but these cannot be 

 combined in the normal reflex cycles in the absence 

 of the ectostriatum and hyperstriatum. 



Removal of the cerebral cortex alone, that is, the 

 surface of the hemisphere to a depth of about an 

 eighth of an inch, leaving a portion at least of every 

 part of the striatum intact, results in little permanent 

 modification of the behavior of the caged bird. A 

 complete breeding cycle can be carried through. The 



