CEREBRAL LOCALIZATION 161 



recognized by touch (astereognosis). A year later, 

 movement was recovered, except for some spastic 

 paralysis in the two ulnar fingers ; there were still 

 astereognosis, inaccuracy of location, and slight 

 dulling of sensation over the ulnar border of the 

 hand. If the lesion had involved the postcentral 

 convolution, the sensory symptoms, in his experience, 

 would have been much more marked. The athetosis 

 was cured. 



Interference with sensation is of course no proof 

 that a cerebral tumour is in the cortex ; it may be 

 found with a lesion of the optic thalamus, internal 

 capsule, isthmus, pons, or medulla. In twenty-six 

 cases of hemiplegia due to some trouble in the internal 

 capsule, Bergmark found evidence of sensory im- 

 pairment in all who were intelligent enough to be 

 tested with accuracy by modern methods, although 

 there was never complete hemiansesthesia to all forms 

 of stimuli. 



FUNCTIONS OF THE FRONTAL CORTEX: 



It is well known, of course, that the great motor 

 centres are limited to the ascending frontal or pre- 

 central convolution. This has been abundantly 

 proved by many methods : by the study of paralysis 

 following localized lesions in man or removals in 

 man or apes ; by electrical stimulation in man and 

 apes ; and histologically, by the limitation to this 

 region of the giant pyramidal or Betz cells, which are 

 the only cells to undergo chromatolysis when the 

 pyramidal tracts are destroyed in the spinal cord. 



It often becomes of great importance to the surgeon 



II 



