244 Considerations on Function [CHAP. 



So much for histology and topography. Functionally, according to Flechsig, this portion 

 of the brain forms a " great anterior centre of association," analogous to his " great posterior 

 centre of association " in the parieto-temporal region ; further, its central part, namely the 

 anterior half of the middle frontal convolution, constitutes a nodal point for the long systems 

 of association linking it with numerous sensorial zones; the peripheral portion is less 

 active. The anterior centre is not so important as the posterior, but like the latter it 

 controls the association of ideas, it is a " Denkorgan," and has a high psychic function ; it 

 contains the mechanism which exercises a higher control over the various " Sinnesorgane," 

 and having specially intimate connections with the great central " projection centre," which 

 includes the motor area, it may particularly serve for storing up memories of volitional 

 movements. 



Very briefly and imperfectly stated these are Flechsig's chief conclusions regarding the 

 role played by this cortex. I do not enter into them fully because it is the basis upon 

 which the conclusions are founded more than the conclusions themselves which interests me, 

 nor shall I embark on a summary of the criticism mostly hostile with which the views 

 have met. 



HISTOLOGICAL DATA. 



It is evident from Kaes' descriptions, that in the very careful and comprehensive exami- 

 nation of the cortex which he made, many of the peculiarities of fibre arrangement which 

 I have detailed were noticed, but as I have said elsewhere, his diagrams fail to convey 

 a clear idea of the topographical distribution of the variations, hence his work is being left 

 out of consideration. Hammarberg's work too on the cell lamination, although most thorough 

 in detail, and for that reason valuable, is wanting in the same respect as Kaes'. 



Of researches on the histology of the frontal cortex in conditions of disease, most of 

 those which I have had the opportunity of reading are too fragmentary to merit discussion, 

 but there are two, one recently, and the other comparatively recently published, to which 

 special mention must be made, those of Bolton and Schaffer. 



The former chose for investigation the brains of individuals mentally afflicted. First 

 studying the naked-eye appearances of 200 cases of dementia, he came to the conclusion 

 that the amount of cerebral wasting varied directly with the amount of existing dementia : 

 concerning the important point of the regional distribution of the wasting, he wrote that, 

 "(1) The greatest amount occurs in the prefrontal region (anterior two-thirds or so of the 

 first and second frontal convolutions, including the neighbouring mesial surface, and the 

 anterior third also of the third frontal convolution). (2) The wasting is next most marked 

 in the remainder of the first and second convolutions," and so on. He next gave an account 

 of the microscopic examination of the prefrontal cortex at a fixed point (the anterior pole 

 of the hemisphere in the region of the second frontal convolution, and at right angles to 

 the transverse fissure of Wernicke) in a series of cases, and finding that in dementia the 

 layer which wasted most was the second or pyramidal layer (Bolton's second layer includes 

 the small and medium-sized pyramids and the external layer of large pyramids), he finally 

 concluded that these cells subserve the psychic functions of the cerebrum, and that " the 

 anterior centre of association " of Flechsig is the region concerned with attention and the 

 general orderly co-ordination of psychic processes. 



