CEREBRAL LOCALIZATION 



683 



vexity of the posterior central convolution, while the Rolandic sulcus 

 itself is already partly motor. This deduction which is based chiefly 

 upon histological evidence, has been greatly strengthened by Gushing,^ 

 who, for reasons of diagnosis, resorted to the stimulation of the centro- 

 parietal region in two conscious patients. The positive statement is 

 made that distinct sensations of numbness and touch were aroused 

 which persisted as long as the stimulation remained confined to the 

 post-Rolandic area. This evidence is in agreement with the distri- 



Centrcd Sulcus 



Mid-^^^^"- 



Nucltus of funiculus 

 ciracilis ^fun.cunealus 



^Internal arcuate fibers 



QJ Id in at CorcL 



Fig. 345. — Schema Repeesenting the Origin and Course of the Fibers of the Median 

 Fillet — the Intercentral Paths op the Fibers op Body Sense. {Howell.) 



bution of the afferent paths of the spinal cord and principally of those 

 fibers which form its posterior funiculi. We know that the impulses 

 arriving in the nuclei of these tracts, are transferred to secondary 

 neurons forming the internal arcuate bundle, which crosses the mid- 

 line in front of the decussation of the motor (pyramidal) tracts. This 

 fact is important, because it explains the contralateral character of 

 defects in these sensations. Beyond their decussation the sensory 



^ Amer. Jour, of Physiol., xxiii, 1909. 



