308 INTRODUCTION TO NEUROLOGY 



cortex itself is innate, and in adult life the cortex has acquired many more 

 characteristics similar to those of the brain stem, with its own systems of 

 acquired automatisms and habitually fixed types of response. The larger 

 association centers retain their plasticity longest, but ultimately these also 

 cease to exhibit new types of correlation, and this marks the onset of 

 senility. 



The relations of the cerebral cortex to the cerebellar cortex and the 

 brain stem have been compared (p. 192) to those of an enlarged judicial 

 branch of the central government charged with the duty of interpreting the 

 decrees of the lower legislative centers and dominating the administrative 

 machinery, and with the additional power of shaping the general policy of 

 the government. 



Dewey's stimulating analysis 1 of the reflex arc concept or, as he prefers 

 to say, the organic circuit concept implies that the synthesis of the elements 

 of a complex chain reflex into an organic unity is the essential prerequisite 

 of that apperceptive process which will make the total experience of value 

 for future discriminative responses for learning by experience. This, 

 which is true in the individual learning process, is also true phylogenetically. 

 The correlation centers (and their capacity for the preservation of vestiges 

 of past reactions) are the organic mechanism for this synthesis. They make 

 it possible that a new stimulus may be reacted to, not as a detached element, 

 but as a component of a complex series of past and present adjustments, to 

 which it is assimilated in the association centers apperception. This 

 assimilation or apperceptive process is an integral part of the receptor proc- 

 ess in the higher centers, giving the quale to the idea of the exciting object. 

 Cotemporaneously with this stimulus-apperception process we have an 

 apperception-response-activity giving the object- or purpose-idea, so that 

 the entire reaction is to be regarded as stimulus-apperception-response, as a 

 functional unity rather than as a sequence: stimulus j>apperception> re- 

 sponse. 



Dewey's organic circuit concept is elaborated in terms of psychology. 

 Let us see how it may be applied to biological behavior. 



The simple reflex is commonly regarded as a causal sequence: given the 

 gun (a physiologically adaptive structure), load the gun (the constructive 

 metabolic process), aim, pull the trigger (application of the stimulus), dis- 

 charge the projectile (physiological response), hit the mark (satisfaction of 

 the organic need). All of the factors may be related as members of a simple 

 mechanical causal sequence except the aim. For this in our illustration 

 a glance backward is necessary. An adaptive simple reflex is adaptive 

 because of a pre-established series of functional sequences which have been 

 biologically determined by natural selection or some other evolutionary 

 process. This gives the reaction a definite aim or objective purpose. In 

 short, the aim, like the gun, is provided by biological evolution, and the 

 whole process is implicit in the structure-function organization which is 

 characteristic of the species and whose nature and origin we need not here 

 further inquire into. 



Now, passing to the more complex instinctive reactions, so far as these 

 are unconscious automatisms, they may be elaborations of chain reflexes 

 of the type discussed above (p. 61). But the aim (biological purpose) is 



1 The Reflex Arc Concept in Psychology, Psych. Rev., vol. Hi, p. 357, 

 1893. See also Dewey's later statement in Jour. Philos., Psych., and Sci. 

 Methods, vol. ix, Nov., 1912, pp. 664-668, especially the.f ootnote on p. 667. 



