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630 PHYSIOLOGY CHAP. 



can become motor, i.e. how speech, which was originally dependent 

 on the auditory word centre, is later, in certain individuals, 

 associated with the motor word centre, which may thus alone 

 subserve it. The motor word centre is so connected with the 

 auditory word centre that it is inconceivable that any separate 

 education can make it predominant over the latter. 



Among the most characteristic forms of speech disturbance 

 due to lesions of the cerebral cortex, is that which has been well 

 described as verbal amnesia, since it is clinically quite distinct from 

 verbal deafness. In the one there is more or less complete loss of 

 memory of the auditory images of speech ; in the other it is 

 merely the power of recalling such images that has gone. While 

 the patient suffering from word deafness cannot understand spoken 

 language and is incapable of speaking, the patient with verbal 

 amnesia understands perfectly, and without hesitation, whatever 

 is said to him ; and he can pronounce every word easily ; but his 

 speech is more or less hesitating and unintelligible, as he cannot 

 recall a large number of words, particularly proper names and 

 substantives. " The idea is there, but the word fails, although 

 articulation is not defective " (Kussmaul). " The idea does not 

 call up the word, but the word can always reawaken the idea, for 

 the patient can repeat and understand the word which is suggested 

 to him, and which corresponds with the idea he wants to express " 

 (Tamburini). The auditory and motor word centres are capable 

 of reacting to the external stimuli, but have become incapable of 

 reacting to the internal stimuli of ideational activity. 



Many authors have confused amnesia with word deafness, and 

 maintain that they differ only in degree. It is true that word 

 deafness necessarily involves amnesia ; but their co-existence is 

 not absolutely inevitable, for verbal amnesia may be present 

 without a trace of word deafness. 



Even if both forms imply a lesion of the auditory area, 

 pathological anatomy proves their different localisation. In cases 

 of pure verbal amnesia Wernicke's centre, i.e. the posterior part 

 of the left first temporal convolution, is not involved, but only the 

 left inferior parietal lobe, as was seen in typical cases described 

 by Banti, Cornil, Kussmaul, Broadbent, and others. 



XVI. The new and fundamental principle which Flechsig 

 introduced into the physiology of the brain consists essentially, in 

 the distinction which he made between the sensory and voluntary 

 motor centres, which are united by afferent and efferent fibres 

 with the peripheral sensory and motor organs, and the psychical 

 centres properly so-called, which are connected by endogenous or 

 intra- central association fibres among themselves and with the 

 different sensory centres. According to Meynert and Weruicke 

 the " sensory spheres " included the whole of the cerebral cortex ; 

 each of them was connected with the rest by endogenous, and 



