344 RESEARCHES ON CORTICAL LOCALISATION AND 



in degree, resemble the " opinions " of many of the one-idea-ed 

 " cranks " in the outside world. 



It may be remarked that these various abnormal types of 

 cerebral activity are at present chiefly of academic interest, apart 

 from their obvious bearing on criminology. Our knowledge of the 

 psycho-physiology of the brain is still in its infancy, and though 

 it .is at any rate certain that in such cases the cerebrum is not 

 functioning in a normal manner during the phases of " alteration 

 of personality," not only is no satisfactory explanation yet forth- 

 coming, but it is even difficult to be certain in the complicated 

 cases which of the several phases represents the " normal." It 

 is probable, however, that the subject will receive illumination 

 when our present crude acquaintance with mental disease is 

 replaced by the scientific knowledge which will undoubtedly 

 follow its systematic study. 



Though the more difficult question of the time-related recording 

 of psychic experience in the cerebrum, and of the influence of this 

 on the normal processes of cerebral association, is at present an 

 obscure one, the simpler problem of the manner in which the 

 immediate functions of the cerebrum are performed derives much 

 illumination from the study of insanity. It would be an un- 

 warrantable digression to discuss here the various abnormal 

 types of immediate cerebral activity which are met with during 

 the clinical investigation of mental disease. One or two examples 

 may, however, with advantage be introduced for illustrative 

 purposes. 



In certain cases classed under the symptomatological group 

 of " mania," the centre of higher association is in functional abey- 

 ance, and the cerebrum acts as an uncontrolled sensori-psycho- 

 motor machine. Instead of, as normally happens, but a small 

 selected number of the ever-entering stream of afferent impres- 

 sions being noticed, almost every visual and auditory stimulus in 

 the neighbourhood of the patient is accepted. Processes of cerebral 

 association incited by these occur pell-mell, and find motor ex- 

 pression in emotional disturbance, rapid movements, and a riotous 

 display of words. It is impossible to obtain more than the 

 momentary attention of the sufferer. This condition of uncon- 

 trolled sensori-psychomotor activity may last for many weeks, 

 after which the patient becomes, at any rate for the time, sane. 

 Such patients usually exhibit numerous signs of physical and 



