FUNCTIONS OF THE BRAIN 



943 



Following this scheme, van Rynberk has obtained satisfactory 

 evidence of localization of function. Thus the lobulus simplex con- 

 stitutes a centre for the neck muscles, and the elimination of its 

 influence by excision leads to movements of the head (so-called head 

 nystagmus). The anterior extremity is represented by a centre in 

 the crus primum, and the posterior extremity by a centre in the crus 

 secundum, of the ansiform lobule of its own side, and injury in the 

 region of these centres is associated with abnormal movements of the 

 corresponding fore and hind foot respectively. Extirpation of a 

 lobulus paramedianus causes rolling movements of the body around 

 its long axis or bending of the body to one side, and this centre is 

 connected with the muscles of the trunk. A general scheme of the 

 localizations in the mammalian cerebellum is given in Fig. 379. 



Fig. 379. Bolk's Scheme of the Mammalian Cerebellum. On the right half, certain 

 localizations are indicated (Mills after Von Bechterew). 



It must be remarked that the areas connected with the co- 

 ordination (synergia) of the muscles concerned in particular move- 

 ments cannot be so sharply localized on the surface of the cere- 

 bellum as the areas connected with the discharge of the movements 

 can be localized on the surface of the cerebrum. It is stili an open 

 question whether in the function of these centres only the cortex 

 of the lobules is concerned, or in addition the corresponding por- 

 tions of the central nuclei of the cerebellum. These observations 

 are supported by other facts. For example, microscopical studies 

 have shown that definite regions of the cerebellar cortex are especially 

 connected with definite levels of the spinal cord. Further, the 

 lobulation of the cerebellum in mammals keeps pace with the in- 

 crease in complexity of the voluntary motor apparatus of the whole 

 body, and the variations in the degree of development of definite 

 lobules are related to the variations in the anatomical and physio- 



