PROBLEM OF THE CEREBRAL CORTEX 35 



built up around this dominant sense. In each of these 

 cases a different cerebral reflex center — optic, olfac- 

 tory, gustatory — is greatly enlarged and correlation 

 fibers from other sensory centers converge into it, so 

 that this particular center, no matter where situated, 

 becomes the center of highest physiological domi- 

 nance, tending to control the general behavior 

 patterns. 



Among the fishes very many illustrations of this 

 principle might be cited (for a few examples, see my 

 Neurological Foundations of Animal Behavior, 1924, 

 chap. xiv). As the behavior pattern becomes more 

 complicated in land animals, this primitive form of 

 adjustment apparatus is inadequate, and special 

 correlation centers are developed above and more or 

 less separated from those primary sensory centers 

 which receive their excitations directly from the 

 periphery. Thus arise the correlation centers of the 

 thalamus, corpus striatum, and cerebral cortex, each 

 of which is an adjusting mechanism for many different 

 sensory systems no one of which is physiologically 

 dominant over the others. This makes for greater 

 freedom and plasticity of behavior and larger capacity 

 for modifying innate reflex and instinctive behavior 

 patterns in terms of personal experience; that is, it 

 facilitates learning by experience. 



In the course of vertebrate evolution the center 

 of highest physiological dominance within the brain, 

 that is, of most effective control of behavior, has 



