340 RESEARCHES ON CORTICAL LOCALISATION AND 



the sufferer from aphasia is sane, but at the same time suffers 

 from intellectual disability. 



As has been remarked earlier in this article, the prefrontal 

 region (No. 10 of Brodmann) is the highest zone of association, 

 and insanity depends on sub -evolution or dissolution of this region. 

 In the case of sub -evolution the patient may be permanently 

 idiotic or imbecile, permanently or temporarily insane, or liable 

 to tbe onset of insanity : in the case of dissolution, according 

 to its degree, the patient suffers from a corresponding grade of 

 permanent dementia. 



On the other hand, it has been stated that the post- and infra- 

 Rolandic regions of the cerebrum contain the sensory projection 

 spheres and the various zones of association subserving the 

 complex associational processes which occur with regard to the 

 projection spheres individually and collectively. A gross lesion 

 situated in the " area of Wernicke," i.e. in the very midst of this 

 region of association, must therefore seriously interfere with the 

 performance of the cerebral functions of lower association, namely, 

 with the evolution of percepts of various types and grades of 

 complexity. 



Further, according to the distribution and depth of the lesion 

 almost any grade and type of psycho-sensorial disability may be 

 expected. The greater its proximity to the visual or auditory 

 projection spheres, the greater must be the likelihood of relatively 

 pure word blindness or deafness. For reasons already stated, 

 the former of these disabilities can only occur in persons who 

 have learned to read and write, and it is the more likely to exist 

 in a pure form. The latter can occur in either educated or un- 

 educated individuals, and in either case is unlikely to exist in a 

 pure form (see pp. 334-5). 



On the other hand, a lesion, and especially a superficial one, 

 -located away from the projection spheres, would be expected to 

 cause disabilities with regard to the more complicated processes 

 of lower association, with resulting intellectual impairment. 



As will have been gathered from the remarks on the function 

 of language, the complex mechanism which serves as its physical 

 basis must necessarily be co-extensive in distribution with the 

 projection spheres, and the whole region of lower association. 

 The visual and auditory word-centres lie in or near the visual and 

 auditory projection spheres, as words seen and heard are merely 



