SENSE AREAS AND ASSOCIATION AREAS. 203 



gallons 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. In his early experiments Munk 

 insisted that lesions of the cortex involving the area around the 

 central sulcus are accompanied by a state of anesthesia on the 

 other side of the body, hemianesthesia, particularly as regards 

 the tactile and muscular sensations. It is not necessary, perhaps, 

 to go into the details of the long controversy that arose in 

 connection with this point. Both the clinical and the experi- 

 mental evidence has been contradictory in the hands of different 

 observers, 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 

 sensibility, 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. As stated above, Gushing,! 

 in his report upon the stimulation of the cortex in two conscious 

 patients, states that no sensations were aroused by stimuli 

 applied to the anterior central convolution, while stimulation 

 of the posterior convolution aroused distinct sensations 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 

 involve chiefly the muscular sense, pressure and temperature 

 sense, and the judgments or perceptions based upon these 

 sensations, while the sense of pain is affected but little, if at 

 all. Monakow gives the order in which sensory defects manifest 



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

 p. 621. t Gushing, loc._cit. 



