PROBLEM OF THE CEREBRAL CORTEX 33 



attitudes and movements. The cerebellar arcs are 

 knit into the elementary reflex systems in the most 

 direct way possible. In walking, swimming, and flying 

 they control the execution of movements whose direc- 

 tions and objectives are none of their aff*air. Where 

 the animal is going and what he will do when he gets 

 there are determined in the apparatus of exterocep- 

 tive adjustment, to which the cerebellum, like the 

 rest of the proprioceptive system, is subordinate. 

 Highly elaborated cerebral cortex, on the other hand, 

 is an arbiter of conduct; it participates in the determi- 

 nation of the end to be attained in a behavior 

 sequence; it may revamp the "natural" reflex and 

 instinctive patterns, inhibiting, redirecting, or reor- 

 ganizing them along lines determined within its own 

 organization; its reserves may be drawn upon to give 

 impulsive force to efferent nervous impulses whose 

 motor effect or behavior pattern the cortex itself has 

 conditioned or fabricated; these functions may be 

 performed unconsciously or consciously. The tele- 

 ology implied in these statements is of the same sort 

 as that seen in every lower reflex; that is, the activi- 

 ties of the cerebral cortex are biologically adaptive 

 because its internal organization is such as to work 

 in response to stimulation in ways that yield behavior 

 appropriate to the situation. 



The contrast between cerebrum and cerebellum 

 is very striking in the higher mammals. In rats and 

 other lower mammals, however, it is far less evident. 



