734 



THE CEREBRAL CORTEX, 



FIG. 333. Diagram showing the results obtained by 

 Ferrier from stimulation of the cerebral cortex of the 

 cat. The numbers and letters have a similar mean- 

 ing to those in the last figure, but all are not in- 

 cluded, owing to the fact it was not found possible 

 to differentiate so many distinct actions as in the 

 dog. At the point marked , there was produced a 

 clutching action of the paw with protrusion of the 

 claws. 



and indeed are so easily obtained that it is almost impossible to fail in 



eliciting the response which he marked out as connected with certain 



areas of the Rolandic 

 region. Apart from points 

 of detail, the chief addi- 

 tion to our knowledge of 

 the movements which he 

 found to be provoked on 

 stimulation of the cortex 

 of this region, was the dis- 

 covery that the excitable 

 area extends to the mesial 

 face of the hemisphere, to 

 include the so-called mar- 

 ginal gyrus. Ferrier him- 

 self failed to obtain any 

 definite response from this, 

 but it was subsequently 

 shown l to contain exten- 

 sions of the adjacent ex- 

 citable areas of the external 

 face of the hemisphere, in- 

 cluding an important part 



of the areas for the trunk and lower limb (Fig. 336, B). Ferrier also 



found that removal of the portion of the cortex which on excitation 



produces movements of a 



particular part or limb, is 



immediately followed, unless 



the movement is of a bilateral 



character, by paralysis of that 



part or limb : this had already 



been noted by Fritsch and 



Hitzig in the dog. But in 



the monkey the paralysis is, 



as a rule, much more marked 



and permanent, and in the 



case especially of the upper 



limb may proceed, as in 



monoplegia in man, to the de- 

 velopment of a condition of 



contracture of the muscles and 



permanent immobility of the 



limb (see p. 731). In the leg, 



contracture does not as a rule 



FIG. 334. Diagram showing the results obtained 

 by Ferrier on stimulation of the brain of the 

 rabbit. 0, Olfactory lobe ; X, shallow sulcus 

 running parallel with median longitudinal fissure. 

 1, Advance of opposite hind-limb ; 4, retraction 

 and adduction of opposite fore-limb ; 5, protrac- 

 tion of opposite fore-limb and elevation of 

 shoulder ; 7, retraction and elevation of angle of 

 mouth (obtained over a large area) ; 8, closure of 

 opposite eye ; 9, on orbital aspect opening of 

 mouth with movements of tongue ; 13, protrusion 

 of opposite eyeball, and occasionally turning of 



head to opposite side ; 14, sudden retraction 

 and elevation or pricking of opposite ear ; 15, 

 torsion or closure of one or both nostrils (often 

 associated with movement of ear). 



occur, but after a time move- 

 ments begin to reappear, until 

 eventually it is difficult to 

 determine that any motor 



paralysis exists ; the same may also be the case with the arm. If, how- 

 ever, the whole portion of the Rolandic region which is connected with 

 the particular limb has been removed or destroyed, unilateral move- 

 ments of a truly voluntary nature do not reappear; the movements 



1 Horsley and Schafer, Proc. Roy. Soc. London, 1884, vol. xxxvi. p. 437. 



