216 CEREBRAL LOCALIZATION 



by cutting frozen sections and then piecing them 

 together again ; by this means it was possible to 

 build a frame of metal to fit about the head of a 

 Uving monkey, carrying an insulated needle which 

 could be thrust, through a small trephine hole, into 

 any desired portion of the cerebellum, its cortex, 

 or its deep nuclei (roof nuclei), the exact position of 

 the point of the needle having been determined by 

 a study of the head reconstructed from the frozen 

 sections. By this means various parts could be 

 stimulated electrically without doing any but the 

 slightest damage to the overlying structures ; more- 

 over, by passing in a strong current and using a 

 double needle shielded nearly to the points, small 

 electrolytic lesions either of the cortex or of the 

 roof nucleus could be made, and the resulting 

 degenerations studied by suitable staining some 

 weeks afterwards. 



The general result was to prove that the cortex 

 cerebelh is a receiving platform, and that its axons 

 merely pass to the roof nuclei, from which the efferent 

 tracts start. Stimulation of the cerebellar cortex by 

 ordinary currents produces no obvious response ; 

 stimulation of the roof nuclei causes movements of 

 the eyes and sometimes of the limbs. We see here 

 the reason why laterally situated tumours or abscesses 

 lie so quiet. 



The classic signs of a lesion of the cerebellum, 

 determined both by physiologists and by clinicians, 

 are the following : — (i) Ataxia ; (2) Atonia ; 

 (3) Asthenia ; (4) Tremor : these all affect the same 

 side as the lesion ; (5) Nystagmus ; (6) Vertigo. 



