THE FORE-BRAIN 



559 



F. Krause's recent and numerous experiments on localisation of the 

 motor area in the human brain by means of unipolar faradisation. 

 His results coincide perfectly with those of Sherrington for 

 anthropoid apes, in so far that they demonstrate the inexcitability 

 of the postcentral convolution, and limit the human motor 

 cortical area to the precentral gyrus. He further succeeded in 

 differentiating more fully the excitable points corresponding to 

 different movements of the upper limb and face (Fig. 283). 



There can be no doubt although there is no direct evidence 

 that the excitable area of the human brain also extends to the 



Fio. 283. Electrically excitable region of human cortex. (F. Krause.) The black dots on the 

 surface of the precentral convolution indicate the different motor centres ; /, sulcus centralis 

 or fissure of Rolando ; a, extension and internal rotation of foot ; b, elevation and abduction of 

 arm ; c and rf, flexion of knee ; e, ulnar flexion ; /, palmar flexion ; g, radial flexion ; h, dorsal 

 flexion of hand ; i, p, q, r, movements of thumb ; I, flexion ; m, extension of four lingers ; n, 

 extension ; n, flexion of index finger ; s, extension of little linger ; t, eyelid of opposite side ; u, 

 movements of buccal angle ; v, of zygomatic muscle and levator of upper lip ; x, of masseters ; 

 y, of external pterygoid muscle. 



introflexed cortex that dips into the lips of the Rolandic sulcus, as 

 has been well demonstrated in the anthropoid apes. 



Some authors have contended that a stronger current is required 

 to elicit motor effects in man and in the anthropoid apes than in 

 the lower animals, and that in man it is more difficult, owing to 

 spread of the excitation to the subjacent centres, to arouse epilepti- 

 form convulsions by electrical stimulation of the cortex. Both 

 these statements were contradicted by Grtinbaum and Sherrington 

 for the anthropoid apes, and by Bechterew and Krause for man. 



V. These experimental observations on the topography of the 

 excitable areas of the brain surface in the higher vertebrates 

 represent the development of the important discovery of Hitzig 



