CEREBRAL LOCALIZATION 223 



caused some numbness of all forms of sensation in 

 the hand. 



It is more difficult to be certain whether the 

 ascending frontal or motor convolution has also any 

 sensory function ; if so, it is less obvious than in 

 the case of the postcentral convolution. Naturally 

 occurring lesions limited to the front of the fissure of 

 Rolando, and carefully studied before and after death, 

 are rare, and the evidence is conflicting ; some 

 showed paralysis but no sensory loss, whereas others 

 had both motor and sensory impairment. Many 

 years ago, before it was realized that the convolutions 

 in front of and behind the fissure of Rolando differed 

 in function. Ransom and also Laycock observed that 

 a tingling sensation was elicited when they stimulated 

 the exposed cortex in a conscious man, and apparently 

 they both applied the electrodes in front of the 

 fissure ; Gushing and others have failed to confirm 

 this. Recently Sir Victor Horsley has published an 

 account of the only case in which he has removed a 

 cortical centre (part of the hand area) without 

 encroaching upon the ascending parietal gyrus (for 

 athetosis). Immediately after the operation there 

 was complete flaccid paralysis of the arm and some 

 interference with sensation. The hand could detect 

 cold, but not warmth, stroking with a wool pencil was 

 not felt on the ungual phalanges, there were inaccuracy 

 of location of pain and touch and loss of the sense of 

 position, and objects placed in the hand were not 

 recognized by touch (astereognosis). A year later, 

 movement was recovered, except for some spastic 

 paralysis in the two ulnar fingers ; there were stiU 



