INTERNAL STRUCTURE OF THE BRAIN STEM 1019 



cortex approach each other in t>pe of specialization. " ding of corti- 



cal types as this, implicating as it does three discrete areas of the neopallium, 

 might well give rise to a contingent of the pallio-ponto-cerebellar system 

 capable of communicating to the lateral cerebellar lobes cs which 



represent a physiological admixture of myoarticular a; ;Iibratorj' 



sensibility with visuaI-«ensor\- elements. Such a combination of impressions 

 received from the muscles and joints, from the semicircular canals and from 

 the eyes would constitute an invaluable accession in the construction of 

 those neural combinations necessary- for the coordinative guidance of move- 

 ments of the extremities, and more particularly the upper extremit>\ 

 W hatevcr function is ultimately ascribed to the occipital contingent of the 

 pallio-ponto-cerebellar system must depend upon future investigation. In 

 general, it may be accepted that this system is connected with the functions 

 of neokinesis, and that its progressive augmentati< c primate series 



indicates a definite increment in the sphere of neokinetic organization. 



The frontal lobe, especially its intermediate precentral area in close 

 relation to the origin of the pyramidal system, also establishes communica- 

 tion with the lateral lobes of the cerebellum through the fronto-ponto- 

 cerebellar contingent. This bundle of fibers is somewhat less in volume than 

 cither the occipital or the parieto-temporal contingents of this system. 

 According to present physiological interpretations of cortical localiza- 

 tion, the intermediate precentral area has functional control over highly 

 skilled motor performances. The fronto-ponto-cerebellar fibers in this light 

 are not difficult to understand. Both the histogenesis and histology" in this 

 region of the human brain furnish excellent reasons to believe that the 

 function of this portion of the cortex is intimately associated with motor 

 activity. Its stratigraphic representation of cells and fibers follows closely 

 the pattern laid down in much clearer outline in the precentral motor 

 convolution. 



