774 THE CEREBRAL CORTEX. 



which in man appears, as the result of clinical and anatomical observation, to 

 be confined to the upper part of the first temporal gyrus and the transverse 

 temporal gyrus, whereas in the monkey it certainly extends far beyond this 

 limit (indeed, extirpation of the whole of both temporal lobes is not in the 

 monkey sufficient to produce complete deafness). And the same principle is 

 illustrated in the case of the visual projection area, Avhich in man appears, from 

 clinical evidence, to be confined to the convolutions bordering on the calcarine 

 fissure ; while in the monkey it undoubtedly extends over the whole of the 

 occipital lobe, which is relatively large in this animal. As regards the olfactory 

 sense, the peripheral <|fgan is so insignificant in all the primates that it is not 

 to be expected that the cortical projection would be at all extensive in any. 

 We have not sufficient knowledge of the exact localisation of the centres for 

 taste and touch to draw a similar comparison. 



APHASIA. 



This term 1 is used to express not only a loss or defect of articulate 

 language, but also " a loss or defect in symbolising relations of things in 

 any way." 2 It occurs as the result of lesions upon the left side of the 

 brain, and especially of the base of the third left frontal convolution. 

 Three degrees may be distinguished, namely (1) Defect of speech {partial 

 aphasia); (2) loss of speech (complete aphasia); (3) loss of gesture 

 language, i.e. of pantomime (amimia) as well as of speech (asemasia? 

 Hamilton). In complete aphasia the patient does not speak intelligibly. 

 He can only utter words without sense, or mere jargon. 



Motor aphasia may show itself simply as a defect in or complete 

 loss of utterance of spoken words (aphemia 4 ), or simply as a defect in or 

 complete loss of the ability to write intelligibly (agraphia), or as both 

 these conditions combined. 



^ The patient may understand what is said or read to him, and 

 remember things told him. "This is important, for it proves that 

 although speechless, the patient is not wordless." Apart from speech his 

 articulatory and vocal organs may be unaffected. He may be able to 

 sing. He smiles, laughs, frowns, and varies his voice so as to express 

 emotions correctly. Although he has lost speech, he has not lost the 

 images of things; he will point to any object which we name, and 

 recognises drawings of objects. He may retain the propositional use of 

 " yes " and " no," and either by these or by pantomime may intelligently 

 assent or dissent to simple statements ; he may have the interjectional or 

 emotional use of certain words, such as oaths, which are uttered under 

 appropriate circumstances, but cannot be repeated at will ; in rare cases 

 a proposition is stated or a question is asked intelligibly, but always under 

 the influence of emotion. Some of these instances " show that there is 

 not only retention of some words but of some speech, by the right side 

 of the brain." In point of fact, as Growers insists, /' the left hemisphere 

 has by no means a monopoly of speech function. /The right hemisphere 

 contains structures of similar position and similar connections. These 

 structures can supplement those in the left hemisphere. Loss of speech 

 due to permanent destruction of the speech region in the left hemi- 

 sphere, has been recovered from ; and that this recovery was due to the 



1 6. and 0dcm, speech. 



2 Hughlings Jackson,. Brain, London, 1878, vol. i. p. 311. The quotations and 

 descriptions which follow are chiefly from the same source. 



3 From a and a"r)/j,aLvo}, an inability to indicate by signs or language. 



4 6. and Qrinl, I speak. 



