SENSE AREAS AND ASSOCIATION AREAS. 221 



this localization is at present unsatisfactory.* It does not seem 

 to be certain whether or not, in the case of complete lesion of the 

 center on one side, the ability to speak can be again acquired by 

 education of new centers, t Some recorded cases seem to indicate 

 that this re-education is possible in the young, while in the old it 

 is more difficult or impossible. We express our thoughts not only 

 in spoken, but also in written, symbols. As this latter form of 

 expression involves a different set of muscles and a different 

 educational experience, it is natural to assume that the complex 

 associations concerned or, to use a convenient expression, the 

 memory centers, should involve a different part of the cortex. It 

 is, in fact, observed that in some aphasics the loss of the power of 

 writing, a condition designated as agraphia, is the characteristic 

 defect, rather than the loss of the ability to use articulate language. 

 There may be also, as a result of cerebral injury, a loss of the power 

 to make various kinds of purposive movements or combinations 

 of movements other than those used in speaking or writing, and 

 for this general condition the term " apraxia " has been employed. 

 Using this term in its widest sense, pure motor aphasia (aphemia) 

 might be defined as an apraxia limited to the muscles of articula- 

 tion, and agraphia as an apraxia involving the movements of 

 writing. The general evidence seems to show that these conditions 

 of apraxia, other than the aphemia, are associated with lesions 

 in the first and second frontal convolutions anterior to the motor 

 area. 



Sensory Aphasia. In sensory aphasia t the individual suffers 

 from an inability to understand spoken or written language. 

 Conditions of this kind have been referred to lesions in the cortex 

 of the temporal or temporo-parietal region (H and V, Fig. 96), 

 and, as in the case of motor aphasia, the lesion is usually on the 

 left side. Since the cortical centers for hearing and seeing are 

 situated in distinct parts of the brain, we should expect that the 

 mechanism for the association, in one case of visual memories of 

 verbal symbols with certain concepts, and in the other case, of 

 auditory memories, should also be located in separate regions. 

 Inability to understand spoken language, or word-deafness, is, in 

 fact, usually attributed to a lesion involving the superior or middle 

 temporal convolution contiguous to the cortical sense of hearing 

 (H, Fig. 97), while loss of power to understand written or printed 

 language, word-blindness (alexia), is traced to lesions involving the 



* For these opposing views and the work of Marie see Moutier, "L' Aphasia 

 de Broca," Paris, 1908. 



fSee Mills, "Journal of the Amer. Med. Assoc.," 1904, xliii. 



j Consult Starr, " Aphasia," "Transactions of the Congress of American 

 Physicians and Surgeons," vol. 1, p. 329, 1888; also Monakow, "Gehirn- 

 pathologie," 1906; Collier, "Brain," 1908. 



