318 RESEARCHES ON CORTICAL LOCALISATION AND 



of the psychomotor area. The remainder of the cortex has largely 

 ceased to present embryonic features. 



The cerebrum of the higher primates is thus characterised by 

 the evolution of regions of associational cortex, posteriorly be- 

 tween the projection areas, and anteriorly in front of the psycho- 

 motor area. The former is probably concerned with the higher 

 elaboration of the " sensorial," and the latter with that of the 

 " motor " aspect of the cerebral functions. 



In man the area of cortex devoted to associational functions 

 is enormously enlarged posteriorly, and is still more increased 

 anteriorly by the evolution of a notable pref rental lobe. Con- 

 currently with this increase in the zones of association, language 

 has been evolved, from both " sensorial " and " motor " aspects, as 

 a complex mechanism for the symbolic integration of the various 

 more or less individually complex products of cerebral associa- 

 tion ; and the higher psychic functions, of voluntary attention 

 and inhibition, and of voluntary selection and co-ordination into 

 orderly sequence of the processes of lower cerebral association, 

 have been developed. 



THE HIGHER FUNCTIONS OF THE HUMAN CEREBRUM 



The further consideration of the functions of the cerebrum, 

 namely, the description, or attempted description, of those func- 

 tions which are. peculiar to man, necessitates the passing of the 

 border-line between physiology and psychology. Hitherto the 

 subject of aphasia has been regarded as a branch of the former 

 science, and has fallen under the purview of the neurologist. 

 Recent investigations, in particular those of Marie, have, however, 

 shown that a wider view must be taken of the relationship of 

 language to the psychic functions, and of the influence on 

 these of the disabilities which are described under the term 

 " aphasia." 



As a preliminary to the further consideration of the functions 

 of the cerebrum and to the description of these investigations, it 

 is therefore necessary, for the benefit of such readers as are not 

 versed in psychological terminology, to introduce here certain 

 general observations and definitions. 



As has already been remarked, the cerebrum should be regarded 

 as a great sensori-motor ganglion, the only objective indications 



