THE CORTICAL GRAY MATTER. l8l 



in the superior parietal lobule and praecuneus. Perhaps other 

 parts interpret tactile, pain and temperature impulses. The 

 whole receptive and psychic area of common sensation has been 

 called the somasthetic area (Barker), though the application of 

 this term might better be limited to the receptive area. 



Acustic Center (Figs. 54 and 56). The receptive acustic center 

 is located in the transverse temporal gyri and in that part of the 

 superior temporal gyrus which is continuous with them. In the 

 adjacent part of the superior and middle temporal gyri, in the 

 left hemisphere, is the psychic acustic center. 



Optic Center (Figs. 54 and 55). In the cuneus and lingual 

 gyrus is located the receptive optic center for the temporal half 

 of the same retina and the nasal half of the opposite one; perhaps, 

 also, for the macula lutea of both sides. The remainder of the 

 occipital lobe and, according to Mills and others, the angular 

 gyrus, also, form the psychic optic center. This latter center is 

 probably unilateral and developed only in the left hemisphere of 

 right handed people. 



Olfactory and Gustatory Centers (Figs. 55 and 57). The uncus 

 hippocampi forms the chief cortical center of smell, close to which 

 in the fusiform gyrus is probably the gustatory center (Mills). 

 Paul Flechsig in his recent studies of the human brain locates 

 taste in the gyrus cinguli contiguous to the splenium of the corpus 

 callosum (Fig. 55). The olfactory, auditory, visual, common 

 sensory and motor areas are all distinguished by a definite charac- 

 teristic histological structure, peculiar to each region (Campbell). 

 Medullation of the fibers in these cortical areas occurs at different 

 times; and, according to Flechsig, in the following order: olfactory, 

 tactile and muscular sense, visual, auditory, and gustatory. 



In the temporal lobe Mills locates four other centers which 

 include the pole, the inferior temporal gyrus and a part of 'the 

 middle temporal gyrus (Fig. 56). These are from before back- 

 ward: the center 0} intonation at the pole, the naming center, the 

 center of equilibration, and the center of orientation. 



All the above motor, somaesthetic and special sense areas are 

 provided with projection fibers which connect them with defi- 

 nite muscle groups and surface regions and with the organs of 



