166 Temporal Lobe and Audit or a Areas [CHAP. 



of a widespread lesion, one which brought in its train, not the interruption of a single 

 tract of fibres only, but of a whole series of hitherto unexplored bands, among which 

 projection fibres from the " secondary " auditory centres (to be mentioned hereafter) and the 

 receptive apparatus in the auditory area were to be included. Moreover, he believed that 

 in " word-deafness " the defect was of an associative nature, for on no other supposition 

 could the ability of the patient to hear ordinary sounds with both ears be explained ; at 

 the same time he could give no definite and concise statement as to the particular tracts 

 which were involved, and the same remarks might be applied to the writings of others who 

 have helped to swell the stream of controversy on this subject. 



Amusia. 



Musical or tone deafness may be one of two kinds, of a perceptive nature and in- 

 dicated by an inability to recognise familiar tunes, or of an expressive kind causing the 

 loss of singing and -playing accomplishments; of these the former variety is the commoner 

 but the two may coexist. Again, so far as I am aware, cases of pure " amusia " have not 

 been recorded ; some complication, of which " word-deafness " is the most frequent, always 

 being present. 



As is the case with " word -deafness," so here, the area of cortex presiding over this 

 faculty and also the special routes along which musical stimuli pass if such exist has 

 not yet been made clear; all that we can say is, that instances have been recorded, notably 

 by Edgren, suggesting that bilateral disease of the first temporal lobes is accountable for 

 the disability. In Edgren's case there was an extensive defect in the anterior division 

 of the first and third temporal gyri of the left side, and an area of softening at the 

 posterior end of the Sylvian fissure, involving portions of the superior temporal and supra- 

 marginal convolutions. 



Psych ic Deafness. 



That some dulling of the intellectual faculty should arise, as a secondary result of the 

 cutting off of such an important channel of communication as that for spoken words, is 

 readily supposed, and in point of fact some degree of mental impairment has attended 

 most cases of " word-deafness." This, however, is not the condition to which the term 

 " psychic-deafness " alludes. The term applies to a state, allied to " mind-blindness," in 

 which the individual is unable to interpret or recognise ordinary sounds correctly, thus, a 

 dog's bark cannot be differentiated from a cock's crow, and neither will convey any 

 meaning. But although this condition may exist clinically we are in the dark concerning 

 its anatomical substratum. 



Finally, with regard to the facts gleaned from cases of tumour and abscess of the 

 temporal lobe, in many such cases rough localisation has been determined by an epileptic 

 aura of an auditory character, or by ringing or buzzing sounds in the ears, etc., but as 

 means to the precise delimitation of the auditory area they possess little value. 



C. THE ANATOMICAL EVIDENCE. 



In opening our remarks on the anatomical and histological evidence bearing on the 

 localisation of the auditory area, it will be advisable to state briefly what the auditory 

 neuronic chain consists of. 



