312 RESEARCHES ON CORTICAL LOCALISATION AND 



these grounds alone it is possible to assign to the prefrontal cortex 

 the highest and latest evolved functions of voluntary attention 

 and inhibition, and of selection and co-ordination of the various 

 individually complex processes of cerebral association. The pre- 

 frontal portion of the cortex is thus concerned in the performance 

 of the highest grades of cerebral function, and also bears to the 

 psychomotor area a similar relationship (though in the converse 

 direction as regards action) to that borne by the posterior regions 

 of association to the centres of projection. 



To endeavour to indicate the functions of the cortex of the 

 intermediate portion of the frontal lobes would in the present 

 state of knowledge be to enter the realm of conjecture. It may, 

 however, be remarked that part of this associational zone un- 

 doubtedly contains the physical basis of the motor aspect of the 

 mechanism of language, which is the instrument for the symbolic 

 integration of the various more or less complex processes of cerebral 

 association. Until the recent publication of the investigations of 

 Marie and of Monakow, Broca's area was generally regarded, by 

 neurologists at least, as the region concerned with one portion of 

 this mechanism, namely, the " speech centre." Now, however, as 

 will be indicated later, a much broader view must be taken of 

 the complex mechanism of language, which possesses multifarious 

 associational connections with probably the whole cerebrum. The 

 mechanism of language must in fact be regarded, not merely as a 

 series of cortical centres, one or more of which may be blotted out 

 without more than local interference with the mental functions, 

 but as the absolutely essential factor to the adequate performance 

 of these. 



With reference to the respective functions of the two greatest 

 centres of association, a large body of neurologists, notably Bastian, 

 Hughlings Jackson, Mott, Schafer, and Flechsig himself, are of 

 opinion that gross mental disabilities are more likely to occur in 

 lesions of the posterior centre than of the anterior, whilst Wundt, 

 Hitzig, Ferrier, Bianchi, &c., hold the opposite view. 



From the purely neurological aspect, especially when con- 

 sidering the different varieties of " aphasia," the former view 

 had undoubtedly much in its favour. For example, until quite 

 recently, cases of Wernicke's (sensory) aphasia were generally 

 considered to exhibit gross mental disability, whilst cases of Broca's 

 (motor) aphasia were supposed to be free from this symptom. The 



