218 PHYSIOLOGY OF CENTRAL NERVOUS SYSTEM. 



(paraphasia). Motor aphasias have been classified in various 

 ways to suit the different schemata which have been invented to 

 explain the cerebral mechanism of speech, but the whole subject 

 is in reality so complex that most of these classifications must be 

 received with caution. There seems to be no doubt, however, that 

 a condition of what may be called pure motor aphasia may result 

 from localized injuries to the brain. In this condition there is 

 loss of the power of articulate speech, without paralysis of the 

 muscles of articulation, and with the preservation of what has been 

 called internal language, that is, the power to conceive the ideas for 

 which the appropriate verbal expressions are missing. Most 

 authors conclude that this condition is due to an injury or lesion in 

 Broca's convolution, but others contend that the evidence for 

 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, f Some recorded cases indicate that 

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

 is more diflScult 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 J the individual suffers 

 from an inability to understand spoken or written language. 



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

 de Broca," Paris, 1908. 



t See 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; CoUisr, "Brain," 1908. 



