THE CEREBRUM 593 



jven though the individual hears the sounds as formerly, but though hear- 

 jig them, they cannot be remembered or recalled. To this condition the 

 ! ;erms word deafness and object deafness have been given. 



From the concrete conceptions formed of individual objects of a similar 

 :haracter or of a class, there are developed abstract conceptions, by the 

 uniting into a single idea the elements which are common to all the objects 

 bf the class. This involves an analysis and a synthesis, a recognition of 

 the points of similarity and dissimilarity. The development of abstract 

 conceptions is believed to be associated with the activities of the cortex of 

 one or the other of the association areas (see page 596). 



For the emission of the sounds of words which constitute spoken 

 language it is essential that the sensations produced by the muscle move- 

 ments shall not only be perceived but registered or memorized. Without 

 this the capacity to express words would not be possible. This registration 

 is believed to be associated with the lower portion of the area for muscle 

 sensibility. 



2. The Emissive or Motor Phase. In an attempt to express ideas by 

 spoken or written language the muscles determining the action of the 

 larynx, jaws and' teeth, tongue, lips, hands, etc., are excited to action 

 by nerve impulses descending through nerves, the nuclei of origin of 

 which lie in the gray matter beneath the floor of the medulla oblongata 

 and in the gray matter of the spinal cord. The nuclei of these nerves 

 are in turn excited to action by nerve impulses descending by way of 

 the internal capsule from the cortical areas for the face and arm 

 respectively. 



The Motor Speech Area. By this term is meant an area of the cortex, 

 the function of which is to arrange language for outward expression; for the 

 use of the executive centers concerned with speech, viz.: the laryngeal, lingual 

 and facial centers located at the foot of the pre-central convolution. This 

 area, i.e., the motor speech area, has been assigned to the posterior part of 

 the subfrontal convolution (Broca's convolution) on the left side in those who 

 are right-handed and on the right side in those who are congenially left- 

 handed, and in the anterior part of the insular or perhaps the pre-insular 

 convolutions. Unipolar faradic stimulation of this area fails to call forth 

 any motor response; its destruction by disease, however, is followed by a 

 more or less extensive loss of the faculty of articulate speech or the faculty 

 of expressing ideas with words, a condition usually spoken of as motor 

 aphasia or aphemia. This area and the area at the foot of the pre-central 

 convolution are united by association fibers. 



The Motor Writing Area. By this term is meant an area of the coi 

 the function of which is to arrange language for outward projection; for 1 

 use of the executive centers concerned with writing, viz., the arm 

 located in the middle portion of the pre-cental convolution. This area, t.^., 

 the motor writing area, has been assigned to the posterior half or third oi 

 medi-frontal convolution. Unipolar faradic stimulation of this area fail 

 call forth any motor response; its destruction by disease, however, is followec 

 by an inability to express ideas by writing, a condition usually spc 

 of as agraphia. This area and the general arm center in the pr< 

 convolution are united by association fibers. 

 38 



