1932] Poliak: Afferent Fiber Systems, Primate Cerebral Cortex 215 



portions of the cerebral cortex, and in the existence of a ''spatial" 

 internal org^anization of the somatic sensory, auditory, and ^'^sual 

 afferent paths; they stand in contrast to the attempts to restore in 

 some form or other the old doctrine of the functional equivalence, or 

 omnivalence of the entire cerebral cortex. 



Without a minute and extensive discussion, and without far reach- 

 ing' conclusions, it may be stated in general terms that the results of 

 this study indicate that the whole question of the anatomical organiza- 

 tion of the brain and of its function, is largely one of localization, 

 although our imperfect knowledge makes this principle in many 

 respects appear obscure. The idea of unequal local function of the 

 nervous system in general, and of the cerebral cortex in particular, 

 is as old as modern brain research. During the last hundred years it 

 has undergone considerable modification in details, due to develop- 

 ment in other branches of natural science and to the accumulation 

 of data on the anatomy, physiologj^, and pathology of the brain. 

 Naturall}^ in its early form the localistic conception was "naive," 

 which made it an easy task for its opponents to show its wealv points. 

 But the opposite doctrine, that of an equal or equivalent significance 

 of the whole cerebral cortex has all the characteristics of another 

 extreme, even in its milder, modern form (though some modern 

 authors seem to have returned to the ill-founded integral conception 

 of the cortical equivalence of Flourens and Goltz). In reaction 

 against too simple and rigid a localistic explanation of higher mental 

 and related processes many modern neurologists maintain that in 

 all major activities the greater part of the cerebral cortex or even the 

 entire cerebrum, perhaps together with the whole somatic apparatus, 

 is nearly always involved. Although in some sense acceptable,^ this 

 view undoubtedly over-emphasizes and generalizes a single aspect of 

 the brain 's activity ; for, the same type of explanation could as well 

 be applied to somatic organs and systems, which indisputably have 

 distinctive functions though they are parts of the whole organism and 

 always collaborate more or less in its activities. As Vogt pointed out, 

 the localistic conception is capable of satisfying the demand that it 

 explain the highly complex nervous processes (Vogt, 1919, p. 443). 

 An analytic attack, namely, an attempt to identify and distinguish 

 the different morphological parts and their special functions, appears 

 to be a necessary preliminary before reconstruction of the archi- 



3 See especially the experiments of Lashley showing the participation of large 

 parts of the cerebral cortex in the formation of some of the complex habits. 



