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PHYSIOLOGY OF CENTRAL NERVOUS SYSTEM. 



themselves after such lesions, as follows : The localizing and muscle 

 senses are chiefly affected, in fact, almost lost on the opposite side; 

 the temperature and pressure sense may be affected, while the 

 pain sense is retained or but slightly affected. The clinicians have 

 observed that the most positive and invariable symptom of lesions 

 in this region is a condition of astereognosis, that is, a diminution 

 in what may be called the stereognostic perceptions. By stereog- 

 nostic perception is meant the power to judge concerning the form 

 and consistency of external objects when handled, and it must be 

 regarded as a perception based upon localized sensations of touch, 



Central Sulcus 



^Internal arcuate fibers 



ofhinal CorcL 



Fig. 90. Schema representing the origin and course of the fibers of the median fillet, the 

 intercentral paths of the fibers of body sense. 



together perhaps with those of temperature and muscular sen- 

 sibility. On the whole, therefore, we must infer that the cortex in 

 this postcentral area is concerned with the sensations of pressure, 

 temperature, and muscular conditions, and especially the higher 

 type of these sensations, which we can project or localize accurately. 

 This conclusion is strengthened by the fact that, as described in 



