LOCALIZATION OF LEARNING PROCESS 215 



between the rat and even man"; but only in the light 

 of a remark appearing lower on the same page, 

 "The differences between the rat and the apes are 

 scarcely greater than those between the apes and 

 man." 



It all depends upon what we mean by "funda- 

 mental difference." The difference is certainly signifi- 

 cant, and it seems to me to consist in part in the rele- 

 gation in the human brain of some of the tonic and 

 postural influences to non-cortical (striatal, cerebel- 

 lar, etc.) mechanisms and the tremendous amplifica- 

 tion of the phasic influences of intentional control 

 through processes intrinsic to the cortex. 



The preceding argument is perhaps difficult to fol- 

 low because several different sorts of cerebral activity 

 are enumerated in a single catalogue, and it is not 

 made plain just how these processes are actually re- 

 lated in normal function. The difficulty is in part in- 

 herent in the problem. No single formula is adequate, 

 and the path of progress is strewn with derelict theo- 

 ries discarded because too simple to fit more than a 

 selected few of the known facts. Lashley says (1924, 

 p. 275): 



Recent work in general tends to emphasize the complexity 

 of neural functions. We must hesitate-to ascribe an exclusive or 

 precise function to any neural structure, for the evidence points 

 rather to the view that observable behavior is always the prod- 

 uct of the interaction of many neural systems and that the 

 function of any system is dependent on its temporary physio- 

 logic relation to other systems. 



