114 Anatomy of the Nervous System 



in vascularity in the rat, as have also the different laminae in 

 a given area, which would seem to indicate differences in 

 functional activity^ (PI. XXVII.). 



The main areas have been enumerated by Brodmann as 

 follows :- 



1. Regio postcentralis 



2. Regio praecentralis 



3. Regio frontalis 



4. Regio insularis 



5. Regio parietalis 



6. Regio temporalis 



7. Regio occipitalis 



8. Regio cingularis 



9. Regio retrosplenialis. 



Histological studies reveal a considerably larger number 

 of structurally different areas, however, as may be seen from 

 the accompanying plan of the localization in the cortex of 

 the rat^ (Fig- 10). In the legend for this illustration, the 

 areas indicated are correlated with the terms of Brodmann. 

 It will be observed that the regio frontalis is not mentioned, 

 this area, though exceedingly large in man, being very small 

 in the rat and being completely hidden at the bottom of the 

 rhinal fissure. It may perhaps be that the area marked d 

 also belongs to this region. 



For what is known as to the functions of these areas, the 

 reader is referred to the standard text-books of neurology 



^Similar differences have been shown between various centres in the 

 brain stem and the cerebellum, and the development of these differences 

 in the young rat has been found to be related temporally to the establish- 

 ment of functional activity. 



-Brodmann lists also the olfactory cortex as: 



10. Regio hippocampica. 



11. Regio olfactoria. 



^For details of the histological structure in each area shown in Fig. 10, 

 see F^ortuyn, Arch. Neur. and Psych., Path. Lab. London County Asylums, 

 vol. VL, 1914, or Sugita, Jour. Comp. Neur., vol. 28, 1917. 



