THE ASSOCIATION CENTERS OF FLECHSIG 665 



question, because, while the letters are seen, they are not always recognized 

 as signs of certain definite sounds. The ability to write spontaneously or 

 after dictation is very profoundly affected and the ability to copy is often 

 somewhat reduced. We find likewise when the destruction is somewhat more 

 extensive that it is always difficult and sometimes impossible for the patient 

 to understand writing. 



The disorders which are produced by lesions of the first temporal convolu- 

 tion may vary also according to the mental and literary culture of the indi- 

 vidual. Highly educated persons suffer less in their ability to understand 

 written or spoken words or in their ability to write than do the uneducated. 



Recovery of language powers lost by these various lesions is to a greater 

 or less extent possible. This is explained in part by the assumption of the lost 

 functions by the right hemisphere, and in part possibly by the establishment 

 of new associations by means of collateral and other connections which have 

 been left unharmed. 



When the language powers are destroyed to any great extent, the mental 

 powers must naturally suffer. Here again the extent and duration of the dis- 

 order will depend upon the position and extent of the lesion as well as upon 

 the relative importance of the different components in the person's particular 

 language mechanism. If, as is usually the case, the individual is influenced 

 most by the sound images of words, word deafness would naturally produce a 

 greater reduction in his intelligence than if he relied mainly upon memory 

 pictures of printed or written words. 



Closely related but not identical with the language faculties are the musical 

 faculties. Music constitutes a language of its own, the finer nuances of which 

 are intelligible only to a relatively few favored individuals. Clinical observa- 

 tions made within recent years have shown that brain diseases may cause 

 disorders in these powers exactly similar to those affecting the ordinary lan- 

 guage faculties. Thus we find loss of the ability to sing (vocal motor 

 aphasia), note blindness, loss of the ability to write musical notes (musical 

 agraphia), tone deafness, etc., all of which are comprehended under the 

 general term amusia. There is also a certain degree of independence 

 both in the relation of these to one another and in their relations to aphasia. 

 For example, a person may be able to sing and not to speak, or to speak and 

 not to sing. It is probable that at least certain of the special clinical forms 

 of amusia are anatomically independent, and that they are caused by lesions 

 in the vicinity of those which produce the different forms of aphasia. The 

 localization for that special form of amusia known as tone deafness, which is 

 characterized by loss of the ability to recognize musical sounds as such, is 

 probably in the first or first and second convolutions of the left temporal lobe 

 in front of the region the destruction of which causes word deafness (Edgren). 



3. THE ASSOCIATION CENTERS OF FLECHSIG 



The discussion in the preceding paragraphs has taught us that the higher 

 functions of the brain which are in the immediate service of the mental facul- 

 ties are carried out under the cooperation of several cortical regions. Brain 



