CI R] BR \I. L0< \U/ iTIO 



The middl ■!! lamina is much hypertrophied in tl ailed proj< 



lion areas of tl srel mi m for example, 111 the visuosensory ar< 



Pig. 220 . where il is so thick thai it is usually described as being divided 

 into two parts by a oarrow fiber band the line of Gennari Dimination 

 in the layer occurs in the visuosensory area in long-standing c 

 atrophy. '"It Beems therefore primarily to Bubserve the function of re 

 ceiving afferent impressions whether these arrive directly from the lower 

 sensory neurons or indirectly through other regiot a of I • brum." 



The fifth or inner cell lamina is the firsl to I me differentiated, and 



ii is of extremely constant depth in the adult. It is qo1 much affected in 

 amentia, unless when this is very severe, as in patients who are unable 

 to carry on the ordinary animal functions. In short, 'it suIi-.tv.-s the lower 

 voluntary and instinctive activities of the animal economy"- -(Bolton). 



Taking the results as a whole, it appears thai the region of t ; 

 behind the Rolandic fissure consists of sensory areas and association 

 anas wliieli may be immediately connected with them (visuopsychic and 

 Intermediate postcentral) or mure removed in parietal lobe . Thi 

 tion in front of the Rolandic fissure, on the other hand, contains the 

 efferent areas, of which the precentral may bi irded as of 1"' 



grade. The motor discharges from it an nditioned upon impul 



coming partly from the adjacent intermediate pr. central area, in "which 



again are elaborated those received from the 3< ad partly 



from those coming from the prefrontal region, which is the n om- 



plex /one of association. This last is indeed the Bupreme dominating 

 area. It coordinates or integrates the activities of the other association 

 areas and may be considered as the seal of the i) idence 



for this high evolution of the prefrontal area is v< 3 sti g H - 

 last portion of the cortex to be evolved and the first to tu tro- 



gre8sion. In idiots and iml iles the thickness of the pyramidal cell 



layer in this region is directly proportional to tl tal power, and 



in dementia degrees of retrogression occur thai vary directly with the 

 existing grade of dementia. In normal brains this layer is thi 

 one which varies in depth in differenl individuals. Along with its high 



development in the brain of man. as compared with that of other ani- 

 mals, goes hand in hand a greal increase iii the other association an 



Thought is the product of integration between I various 



tion areas, and articulate and written language the outward ma; 



tion of the proci as. It is owing to the relatively great extent ami com- 

 plexity and constant development of the prefrontal lobe that man 

 excels even the highest apes in his intellectual activil 



1o the relative functional development of this lobe that individuals dif- 

 fer from one another in their mental pOW( 



