CH. Liv.] DEFECTS OF SPEECH. 739 



Speech may be absent in certain forms of lunacy, and temporarily in 

 that defect of will called hysteria. 



It may be absent owing to congenital defects. Children born deaf are 

 dumb also. This is because we think with remembered sounds, and in 

 a person born deaf the auditory centres are never set into activity. By 

 educating the child by the visual inlet, it can be taught to think with the 

 remembered shapes of the mouth and expressions of the face produced in 

 the act of speaking, and so can itself speak in time. 



If a child becomes deaf before it is six or seven years old, there 

 is a liability it will forget the speech it has learnt, and so become 

 dumb. 



In congenital hemiplegia there may be speechlessness, especially if the 

 injury is due to meningeal haemorrhage affecting the grey cortex of the left 

 hemisphere. These children generally talk late, the right side of the brain 

 taking on the function of the left. 



Disorders of speech and voice occur from affections of the larynx, and of 

 the nerves which supply the larynx. Stammering is a want of co-ordination 

 between the various muscles employed in the act of speaking. 



Perhaps the most interesting of the disorders of speech, however, are 

 those due to brain disease in adults. These fall into three principal 

 categories : 



1. Aphemia. A difficulty or inability to utter or articulate words. It is 

 often associated with difficulty of swallowing, and occurs in lesions of the 

 base of the brain, especially of pons and bulb. The blurring of speech 

 noticed in most cases of apoplexy may also be included under this head. 



2. Aphtixia. This is a complex condition in which the will to speak 

 exists, and also the ability to speak, but the connection between the two 

 is broken down. When the patient speaks, the words which he utters 

 are well pronounced, but are not those he wishes to utter. This is often 

 associated with Agruj>hia, a similar condition in respect to writing. It is 

 the form of disordered speech associated with disorganisation of Broca's 

 convolution. 



3. Amnesia. This term includes a large class of cases in which the main 

 symptom is loss of memory for words, or a defect of the association of ideas 

 of things with ideas of words, not as in aphasia with ideas of verbal action. 

 Amnesia is associated with lesions of the intellectual, i.e., the sensory 

 centres of the cortex behind the Rolandic area. We have seen that in this 

 region of the brain there are two important centres, the visual and the 

 auditory, and the parts of these which are associated with words may be 

 called the rutual word-centre and the auditory word-centre. They have 

 not, however, been anatomically localised. In amnesia, either these 

 centres themselves, or the tracts that connect them, are diseased or broken 

 down. 



With regard to the auditory word-centre, impressions for the sounds of 

 words are revived in one of three ways : 



/. Spontaneous or volitional ; owing to accumulated traces which constitute 

 memory, a man when he wants to express his thoughts in words remembers 

 the rounds it is necessary to use ; impulses pass to the motor-centre (Broca's 

 convolution), thence to the nerve-centres, nerves, and muscles of the larynx, 

 mouth, chest, &c., and the man speaks. 



b. In slight disease of the auditory word-centre, he is unable to do this, 

 but if his mind is set into a certain groove he will speak : thus if the 

 alphabet or a well-known piece of poetry be started for him he will finish 

 it by himself. 



c. Mimetic. In more severe cases, a more powerful stimulus still is 

 needed ; he will repeat any words after another person, but forget them 

 immediately afterwards. 



With regard to the visual word-centre ns tested by writing, there are also 

 three ways of reviving impressions for written words or letters. 



BBS 



