864 A MANUAL OF PHYSIOLOGY . 



in ' internal ' speech processes, or in which motor or kinaestheltic 

 ' speech memories ' are stored but simply a ' motor ' area for the 

 movements of articulation. He maintains that there is but one 

 form of true aphasia the aphasia of Wernicke which has for its 

 basis a lesion of the so-called zone of Wernicke (the supramarginal 

 and angular gyri, and the posterior portions of the first and second 

 temporal convolutions) . This, according to him, is the true speech- 

 centre. The symptom-complex known as Broca's aphasia, which 

 everybody admits to exist as a distinctly characterized clinical 

 condition, is due, he says, to a double lesion. One lesion causes 

 aphemia (loss of the power of co-ordinating the movements needed in 

 the articulation of words without actual paralysis of the muscles), and 

 the other the disturbance of internal speech, and the difficulty of 

 reading and of writing, which constitute the true aphasia. Accord- 

 ing to Marie, the lesion which causes the aphemia is not even situ- 

 ated in Broca's convolution, but somewhere in a rather badly defined 

 region, which he denominates the lenticular zone, since it includes 

 the lenticular as well as the caudate nucleus, in addition to the 

 external and internal capsules and the cortex of the island of Reil. 

 It would be out of place to enter more minutely here upon such 

 controversial matters. The conclusion which emerges most defi- 

 nitely from the discussion is that Broca's localization was based 

 upon a very narrow foundation, and must probably be modified. 



A so-called temporary aphasia may occur without any structural 

 change in the speech-centre for example, during an attack of 

 migraine. In children it may even be caused by some comparatively 

 slight irritation in the digestive tract, such as that due to the presence 

 of a tape- worm. 



In the anthropoid apes no evidence of the existence of any ' speech- 

 centre,' even distantly foreshadowing the human, has been obtained 

 by stimulating the inferior frontal convolution on either side. No 

 movements, and particularly no movements connected with vocali- 

 zation, are elicited. 



Sensory Aphasia. In typical motor aphasia spoken and written 

 wprds convey to the patient their ordinary meaning. They call up 

 in his mind the usual sequence of ideas, but the chain is broken at the 

 speech-centre, and the outgoing ideas cannot be clothed in words. The 

 expressive factor in speech is deranged. In sensory aphasia the percep- 

 tive factor in speech is deranged. In ordinary sensory aphasia (Wer- 

 nicke's, or cortical sensory aphasia) the patient cannot understand 

 spoken or written language, but, far from being unable to speak, he 

 often babbles incessantly. He may string together a series of words, 

 each correctly articulated, but having no meaning, or may utter a 

 jargon not composed of known words at all. Instead of the words 

 which he desires to use to express his meaning, he may use others 

 having a similar sound (paraphasia} . Damage to two regions of the 

 left hemisphere of the brain has been found associated with this 

 strange condition : (i) the upper portion of the temporo-sphenoidal 

 lobe, (2) the angular gyrus and the occipital lobe. When the 

 temporal region is alone affected, it is the spoken word that is missed, 

 the written that is understood (word-deafness}. When, as occa- 

 sionally happens, the lesion is confined to the occipital regiorf, 

 spoken language is perfectly understood, written language not at 

 all (word-blindness}. Sensory, like motor aphasia, may exist in 

 any degree of completeness, from absolute word-deafness or word- 

 blindness, in which no spoken or printed word calls up any mental 



