536 



PHYSIOLOGY 



CHAP. X 



architecture of the different parts of the cerebral cortex, Brodmann 

 plotted out the entire cortical surface into fifty-two areas (Fig. 

 273 a, b) which he grouped into eleven regions or principal fields ; 

 the postcentral, precentral, frontal, insular, parietal, temporal, 

 occipital, cingular, retrosplenial, hippocampal, olfactory. In this 

 way he obtained a surface localisation, a sort of geographical chart, 

 of the cerebral cortex. The definition of the different areas is 



FIG. 269. Cytotectonie type of cortex of occipital lobe of adult man, in which the fundamental 

 type of six layers persists. (Brodmann.) Magnification 66 diameters. 



possible owing to the fact that the structural peculiarities char- 

 acteristic of each area are sharply limited (Fig. 268), so that it 

 is tolerably easy in serial sections to recognise and fix the limits 

 which mark off each area from the adjacent regions. 



The special importance of Brodmann's regional subdivision for 

 the physiologist and neurologist is, as he clearly brings out, that 

 while the greater number of the fields thus defined have as far 

 as is known no connection with actual physiological functions, 

 some of the areas, and precisely those which are characterised by 



