1268 



HANDBOOK OF PHYSIOLOGY 



NEUROPHYSIOLOGY II 



scribed completely by Luciani (188-190) who used 

 the term astasia. All observers since Luciani have 

 described the massive, coarse tremor of the head, 

 neck and shoulders. This tremor was particularly 

 evident when the animal approached a food dish, 

 gradually compensated but never completely dis- 

 appeared. The inadequacy of timing and direction 

 of movement of limbs which at first made walking 

 impossible gradually improved, but the animal always 

 walked with abducted limbs. In spite of the wide 

 base, poor placement of feet and timing of contrac- 

 tions frequently resulted in swaying for which the 

 animal could compensate only by crossing one leg 

 over the other. 



For reasons which still remain unknown, not all 

 types of movement were ataxic. This was confirmed 

 by Dusser de Barenne (113, 114) who was struck b\ 

 the normality of the .scratch refle.x, by the lack of dis- 

 turbance of the movements engaged in by dogs seeking 

 to bite fleas and by the grace of the movements by 

 which cats cleaned their snouts with their forepaws. 

 Becau.se of the ability of the decerebellate animal to 

 perform such complicated movements without ataxia, 

 Dusser de Barenne concluded that the major function 

 of the cerebellum was related to the control of loco- 

 motion. 



The same evidences of cerebellar ataxia have been 

 described in the primate after total ablation (9, 123, 

 188-190, 249, 290). Munk (249) described clearly the 

 disturbance of progression in complicated movements, 

 a sign which Holmes (158) later called decomposition 

 of movement. 



Unilatnal Cerebellar Ahlatwns 



Since it had been recognized even prior to Luciani's 

 studies that signs of cerebellar deficiency were most 

 obvious on the ipsilateral side of the body, Luciani 

 considered the u.se of hemidecerebellation as one of 

 the most valuable experimental maneuvers (188-190). 

 He argued that such an ablation afforded the oppor- 

 tunity to compare a completely normal and a de- 

 ficient side in the same animal and thus obtain a more 

 sensitive measure of the induced deficiencies. Bremer 

 has pointed out the error of the assumption that the 

 effects of unilateral ablation are completely unilateral 

 (36) by demonstrating tiie diflferences between the 

 effects of a) splitting and removing one half of the 

 cerebellum, h) removing one cerebellar hemisphere 

 only, and i) sectioning the cerebellar peduncles of one 

 side. Furthermore, histological changes on the 'intact' 

 side inevitablv occurred (301 ) after lesions which were 



strictly unilateral in their initial distribution. The 

 crossing of some of the ventral spinocerebellar fibers 

 and the crossed fastigiobulbar fibers were inevitably 

 interrupted In' unilateral ablations. Nevertheless, the 

 studies of hemidecerebellation have been of value 

 in confirmin<< and refining the conclusions drawn from 

 the study of the results of total ablation. 



SIGNS OF INHIBITORY wiTHDR.wv.AL. It has been gen- 

 erally agreed that the spastic phenomena resulting 

 from release from inhibition occurred on the ipsi- 

 lateral side of the body (113, 114, 182, 184, 188-190, 

 278, 290, 335). These were exhibited as pleurotho- 

 tonus, forelimb rigidity, and rotation of the head, 

 neck and eyes. In the quadruped these abnormalities 

 persisted for approximately one week and then begin 

 to abate. In the primate the signs were essentially 

 similar to those in the dog and cat but less intense and 

 less cndurins; (29, 123, 182, 188-igo). 



SIGNS OF F.\ciLiT,^TORY wiTHDRAVV.AL. The hypotonia 

 and weakness of the musculature of the ipsilateral side 

 of the body were more clearly evident after hemi- 

 decerebellation by contrast with the contralateral side. 

 During quiet standing, after the abatement of the 

 spasticity, hypotonia was manifest by the gradual 

 sagging of the body to the operated side as the limbs 

 collapsed. The weakness of muscular contraction 

 aLso became evident during walking through the 

 tendency of the legs to fold. These observations of 

 Luciani (188-190) have been confirmed (290, 335). 

 However, Lewandowsky (182, 183) and Dusser de 

 Barenne (113, 114) were unable to agree with 

 Luciani's designation of some of the signs as asthenia 

 and atonia. The weight-bearing tests devised by 

 Rademaker (277) failed to reveal evidence of atonia 

 and asthenia, but it must be emphasized that the 

 observations were made during the period of stabilized 

 deficiency and therefore could ha\c been too late. 

 Rademaker did, however, make one group of observa- 

 tions which indicates one possible .source of the atonia 

 which others observed. With his animals in the supine 

 position, he noted that the forelimb ipsilateral to the 

 lesion was rigidly extended but that the spasticity 

 disappeared upon elicitation of a positive supporting 

 reaction from the contralateral limb. It went un- 

 recognized that these exaggerated effects of contra- 

 lateral inhibition could contribute to atonia on the 

 affected side when the animal was in the normal stand- 

 ing position. Similar observations were also reported 

 b\ .Simonelli (299) who introduced valuable but 



