THE CEREBRUM. 511 



the power to express ideas with words. To this condition the term 

 aphasia was given. Though of limited application etymologically, 

 the word is now employed in a wider sense to signify "partial or com- 

 plete loss of the power of expression or comprehension of the con- 

 ventional signs of language, " words either spoken or written, due to 

 lesions of different portions of the cortex, and especially on the left 

 side. 



Aphasias are of many degrees and kinds, though they may be in- 

 cluded in the two general divisions, motor and sensor. 



Motor aphasia may be either ataxic or agraphic. In ataocic 

 aphasia the patient is unable to express or communicate his thoughts 

 by spoken words, owing to an inability 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 com- 

 municate his ideas by writing through an inability to execute the 

 necessary movements, though retaining his mental processes. In 

 this form of aphasia the lesion is in the writing area. 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 neighborhood of the supra-marginal convolution. 

 In auditory aphasia or amnesia the patient cannot understand 

 articulate or vocal speech, though capable of hearing and understand- 

 ing other sounds, through an inability to distinguish tone intervals 

 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. 



Bilateral Representation. Though highly specialized move- 

 ments, such as those performed by the arms and hands, legs and feet, 

 have their areas of representation on one side of the cerebrum only, 

 and that, opposite to the side of the movement, less highly specialized 

 movements, such as the masticatory, phonatory, respiratory, and 

 various trunkal movements, which require for their performance 

 the cooperation of muscles on both sides of the body, have their 

 areas of representation on both sides of the cerebrum; the area of 

 either side exciting to action the muscles on both sides of the body. 



