FOREWORD 



The investigations of the three chief afferent fiber systems in 

 primates published herein represent only part of a more extensive 

 experimental study of the fiber systems of the cerebral cortex. The 

 original object of this study was to investigate the comparatively little 

 known association connections of various cortical areas as determined 

 by cytoarchitectural and myeloarchitectural investigations. The neces- 

 sity for such a systematic investigation of association and other fiber 

 systems according to cortical areas and regions was plainly recognized 

 by C. and 0. Vogt (1919, pp. 286, 287; 1929) and by Economo- 

 Koskinas. In the course of this work, however, it soon became evi- 

 dent that knowledge of the association connections alone would be of 

 little value unless the afferent paths and their terminal areas or 

 regions in the cortex were well-known. For this reason attention was 

 directed to the study of the three main afferent paths: the somatic 

 sensory, the auditory, and the visual. The selection of these afferent 

 paths can easily be understood in the light of their preponderant 

 importance in the mental processes and others related thereto, in man 

 and other primates. 



In general the importance of knowledge of the afferent paths for 

 understanding the cerebral mechanism and its function has been fully 

 recognized by a series of investigators. In Henschen's (1918, p. 438) 

 opinion, 



A knowledge of the position, of the extent, and of the organization of the 

 primary sensory regions (that is, of the projection fields of the cerebral cortex) 

 is the foundation of anatomical-physiological brain-psychology, and is there- 

 fore the indispensable requirement and the first problem to be solved before we 

 can form a clear anatomical idea of the processes involved in the creation 

 of the mind. 



The ultimate goal of this as of any other brain research is well 

 formulated by Flechsig (1927, p. 120) : 



The main problem for the future undoubtedly will be an all-embracing 

 psycho-physiology; otherwise in the future, as has happened in the past, posi- 

 tive knowledge will be menaced by an overgrowth of the mystic element; 



and again by Henschen (1919, p. 58) : 



Since the mind depends on the function of our sense organs, it is evident 

 that a knowledge of the localization, the extent, and the delimitation as well 

 as of the anatomical organization, and physiological performances of our cere- 

 bral sensory areas represents the foundation of a scientific psychology, and 

 that progress in our understanding of psychic processes depends on full clarity 

 concemiag the gateways of the afferent impulses from the source of experience. 



[vii] 



