6o8 TEXT-BOOK OF PHYSIOLOGY 



the patient is unable to express or communicate his thoughts by spoken 

 words, owing to an inability to arrange words for outward expression and 

 hence to execute those movements of the mouth, tongue, etc., necessary for 

 speech without there being any paralysis of these muscles. The lesion is 

 usually in the third frontal convolution and most frequently associated with 

 right hemiplegia. In agraphic aphasia the patient is unable to communicate 

 his ideas by writing through an inability to arrange verbal signs for outward 

 expression and hence to execute the movements of the hand and arm neces- 

 sary for writing. In this form of aphasia the lesion is in the writing area, 

 in the posterior- half or third of the medi-frontal convolution. These two 

 forms of motor aphasia are not infrequently associated. 



Sensor aphasia or amnesia may be either visual or auditory. In visual 

 aphasia or amnesia the patient is unable to recognize a letter or word, printed 

 or written (though capable of seeing other objects), a condition known as 

 letter or word blindness. It is usually associated with lesions in the neighbor- 

 hood of the supra-marginal convolution. In auditory aphasia or amnesia 

 the patient cannot understand articulate or vocal speech, though capable of 

 hearing and understanding other sounds, through an inability to distinguish 

 the associations of words and letters a condition known as word deafness. 

 It is associated with lesions of the auditory area. 



Paraphasia is an inability to recall the proper words to associate with 

 ideas and necessary to their expression. 



Concept aphasia is the inability to recall the names of objects. It is 

 associated with lesions of the cortex of the mid-temporal or third temporal 

 convolution (Mills). This area is known as the concept or naming area. 



Many other forms of aphasia have been observed and described by 

 clinicians which are fully considered in works relating to diseases of the 

 nerve system. 



The statements regarding the mechanism of speech, the functions as- 

 signed to the motor speech area (Broca's convolution) and the motor writing 

 area, though very generally accepted, have been questioned in recent years 

 by Marie who on the basis of clinico-pathologic facts has presented a some- 

 what different view which has found many adherents. 



Marie's Theory of Aphasia. Marie states that there is but one aphasia 

 and but one speech center, which he locates somewhere in the left temporo- 

 parietal lobe, and which he designates as a specialized intellectual center for 

 speech. Motor aphasia in the accepted sense, he states, is a combination of 

 word blindness and word deafness (both, however, being defects of the speech 

 center) and defective articulation (anarthria) the result of a lesion of the 

 motor tracts necessary to the excitation of the muscles for articulation. The 

 lesion causing the anarthria is in the lenticular zone, in close relation to the 

 lenticular nucleus. This zone, in a horizontal section of the brain, is limited 

 anteriorly by a vertical plane level with the anterior sulcus of the insula, 

 posteriorly by a similar plane level with the posterior sulcus of the insula; 

 internally by the lateral ventricle and externally by the surface of the insula. 

 This zone is anatomically associated with the supra-marginal and angular 

 convolutions and with the posterior portions of the super- and medi-temporal 

 convolutions which together constitute Wernicke's zone. In this view the 

 distinction between motor and sensor aphasia, the functions assigned to the 

 sub-frontal and medi-frontal convolutions and the existence of four speech 



