798 PHYSIOLOGICAL TOPOGRAPHY OF SURFACE OF CEREBRUM. 



In cases of progressive paralysis of the insane, attended with inflammation 

 of the cerebral cortex, the temperature in the axilla is usually higher upon the 

 side on which the paralytic phenomena are situated. Conversely, in the case of 

 convulsions caused by inflammatory irritation of the cortical centers, the tem- 

 perature upon the contralateral side is several tenths of a degree lower during 

 their continuance. If extensive vascular areas are paralyzed, the temperature 

 of the body may fall, for example in paralytics to as low as 25 C. 



Degeneration of the internal capsule gives rise to vasomotor disorders and 

 from this fact it is to be concluded that the tracts for the thermic fibers pass 

 through this structure. The morbidly increased flushing from psychic influences, 

 particularly from fear preceding the onset of the flushing (erythrophobia) , has 

 been attributed by v. Bechterew and Mislawski to irritation of the area discovered 

 by them to have vasodilator effects as a result of experiments on dogs. 



The sensorial areas or the sense-centers are the situations in which 

 conscious perception of sense-impressions takes place. In addition, 

 they constitute also the substratum of sensory conceptions and of sensory 

 memory. The sense-centers are, according to Flechsig, developmentally 

 primordial, that is in so far as they are indicated up to the time of birth, 

 and, secondary, in so far as they attain complete development with their 

 connections at a later period. 



The psycho-optic center, visual center, visual sphere, comprises in its 

 primordial rudiment up to the time of birth the lips of the calcarine 

 fissure (Fig. 262) and the first occipital convolution. In its secondary 

 development it comprises further the entire median surface of the oc- 

 cipital lobe, on the convexity only a small zone within the first occipital 

 convolution and the occipital pole, but not the external occipital gyri 

 and the angular gyms. 



According to clinical observation the first occipital convolution (Fig. 

 246, O 1 ), including the cuneus, contains the optical perception-field. Ac- 

 cordingly, destruction of this region on one side cause homonymous 

 hemiopia. To the patient the half of the visual field of the same side 

 appears not as black, but only as if not present (deficiency of visual 

 perception). In an analogous manner irritative conditions on one side 

 give rise to photopsias in the homonymous halves of the visual fields. 

 Hemiopia, occasionally associated with hallucinations within the blind 

 halves, has been observed. Injury of the region named on both sides 

 (also the effects of poisons, such as alcohol or lead) causes total blindness. 

 Irritation of both centers gives rise to manifestations of light or color, or 

 to visual hallucinations in the entire visual field. Cases, further, of 

 cerebral lesions in which the spatial sense and the light-sense are wholly 

 intact, while the color-sense alone is destroyed, indicate that the center 

 for the color-sense must be especially located within the visual center, 

 perhaps in the most posterior portion of the fusiform and lingual lobules 

 (Fig. 262). Color-hemiopia has even been observed. 



The clinical observations of hemiopia teach that the visual field of each eye 

 can be divided into a larger external and a smaller internal portion, the two being 

 separated by a vertical line passing through the yellow spot. The right or left 

 halves of both visual fields are controlled from one hemisphere. The left halves 

 must be projected upon the right occipital lobe and the right upon the left occip- 

 ital lobe. Thus, every image, on binocular vision, if not too small, must be seen 

 in two halves, the left half from the right and the right half from the left cerebral 

 hemisphere. The yellow spot is in direct connection only with the external 

 geniculate body, and the connecting fibers terminate in the wall of the calcarine 

 fissure. It is a remarkable fact that in case of bilateral hemiopia a small central 

 field of visual activity is preserved. In cases of hemiopia also the action of the 

 pupils is impaired. 



