172 Temporal Lobe and Auditory Arctic [CHAP. 



which may possibly be homonymous with corresponding cells in the visuo-psychic area, and 

 it is possible that they have an analogous function. 



Unfortunately, neither in S. Ramon y Cajal's work, nor in any other publication that 

 I know of, is allusion made to topical differences in the histological structure of the external 

 temporal gyri, so that we can look for no help in this direction ; for the present we must 

 rest content with hypothesis, hoping that the cortical findings in cases of peripheral deafness 

 may throw further light on the question. 



From the clinical and experimental sides also grounds are not wanting for inferring 

 that there exists a separate audito-psychic area, for in spite of the divergent opinions 

 concerning the results of operative measures in this region, we can quote Munk's classical 

 experiments to the effect that removal of a small circle of cortex from the centre of the 

 auditory sphere as defined by him in the dog, produced what he called " mind-deafness " ; 

 we also have Larionow's experiments showing that minor destructive lesions in the auditory 

 area give rise to a loss of appreciation of single tones without interference with common 

 hearing. Then, in the human being, we know, first, that limited lesions of the superior 

 temporal gyrus occasion slight functional disorder, which is dependent upon some degree of 

 psychic disability more than upon actual dulling of acuity of hearing; and, secondly, we can 

 point to the well-known clinical phenomenon of " word-deafness," which more than any other 

 must be due to the obliteration of a psychic realm, and which can yet exist in company 

 with undiminished common audition. 



On these grounds therefore the existence of a special audito-psychic area, located apart 

 from the common audito-sensory area, can hardly be gainsaid, and I submit that the second 

 histological area which I have drawn attention to represents the limits and extent of this 

 field. 



Taking for granted the correctness of the assumption, that the existence of a separate 

 psychic area has to be taken into account, the next point arising for discussion is the 

 degree of representation of that function in the two hemispheres. Are we to believe that 

 the psychic function is equally represented in the two halves of the brain, or has that in 

 the left half a dominant operative capacity ( As regards the interpretation of ordinary sound 

 stimuli (spoken words' are of course excluded here) our clinical and physiological experience 

 leaves little doubt that both hemispheres are equally active, and that just as ordinary 

 visual stimuli are being constantly received and interpreted in both occipital lobes with 

 equal facility, so it is also with ordinary auditory stimuli ; but when we come to consider 

 the question of the interpretation of spoken language it is another matter, for so many 

 cases are on record which seem to prove that the left hemisphere is specially endowed or 

 educated for this purpose that it is fruitless to deny its superiority. At the same time 

 although clinical facts make it obvious that the left hemisphere is mainly adapted for the 

 interpretation of language, it can hardly be maintained that in this respect it is entirely 

 independent of the right hemisphere, because in the only cases of unmixed, complete, and 

 lasting word-deafness on record the lesion has been bilateral ; also cases of word-deafness 

 have been met with in which the lesion has been confined to the right hemisphere ; further- 

 more and this is a very important point, in those cases of word-deafness resulting from 

 a lesion in the left hemisphere, neither has the disability ever been described as having 

 been definitely total, nor have indications of partial recovery ever been wanting, and surely 

 it is logical to infer that the faculty of interpreting spoken language, although dominant 



