202 PHYSIOLOGY OF CENTRAL NERVOUS SYSTEM. 



gations made so far indicate that these termini are located in 

 different regions, and that destruction of any terminus has, of 

 course, the same effect upon the corresponding sense as destruction 

 of the tract in any part of its course. If we go beyond this point, 

 and endeavor to say what part of the complex mental activity asso- 

 ciated with each kind of sensory reaction is mediated by the cells 

 located in these termini, we are met at once with difficulties which, 

 at present, cannot be overcome. Each terminus is connected by 

 association fibers with various other parts of the cortex, and this 

 whole complex of neurons is concerned no doubt in the psychical 

 reactions aroused. 



The Body-sense Area. — Both the chnical and the experimental 

 evidence has been contradictory in the hands of different ob- 

 servers, but the tendency of recent studies has been to show, as 

 stated above, that, whereas the motor areas lie anterior to the 

 central sulcus, the sensory areas concerned with the cutaneous 

 and muscular sensations extend posterior to this sulcus.* Posi- 

 tive cases are recorded in which lesions involving the anterior 

 central convolutions were accompanied by paralysis on the other 

 side, hemiplegia, without any detectable disturbance of sensibihty, 

 and, on the other hand, lesions have been described in the posterior 

 central and neighboring parietal convolutions in which there was 

 a hemianesthesia more or less distinctly marked without any 

 paralysis. Gushing, f in his report upon the stimulation of the cor- 

 tex in two conscious patients, states that no sensations were 

 aroused by stimuli apphed to the anterior central convolution, 

 while stimulation of the posterior convolution aroused distinct sen- 

 sations of numbness and of touch. Such cases tend to support the 

 view that the motor and body sense areas, although contiguous, 

 do not overlap. Regarding the sensory defects associated with 

 lesions of the parietal lobe posterior to the central sulcus (pos- 

 terior central convolution, supramarginal, superior, and possibly 

 inferior parietal convolutions), it seems probable that they in- 

 volve chiefly the muscular sense, pressure and temperature 

 sense, and the judgments or perceptions based upon these sen- 

 sations, while the sense of pain is affected but httle, if at all. 

 Monakow gives the order in which sensory defects manifest 

 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 senses may be affected, while the 

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



* Consult von Monakow, "Ergebnisse der Physiol.," 1902, vol. i, part i, 

 p. 621. 



t dishing, Loc. cit. 



