John F. Fulton 2 1 1 



1 . Phasic movement is integrated by that part of the cortico-ponto-cerebellar 

 system which passes to the neocerebellum. Destruction of the neocerebellum 

 leads to tremors of action which are most conspicuous at the termination of 

 volitional movements. Such action tremors disappear when the precentral con- 

 volution of the cortex is removed. 



2. Postural adjustments are integrated by both systems, the cortico-strio- 

 nigral and that part of the cortico-ponto-cerebellar which joins with the paleo- 

 cerebelltmi.The antigravity and equilibritory postures are adjusted by cortical 

 mechanisms acting in association with the anterior and posterior lobes of the 

 cerebellum, whereas the other more complex postural adjustments, not having 

 primarily to do with gravity or the position of the body in space, find integra- 

 tion through the cortico-strio-nigral system. 



The cerebral cortex thus becomes the common focus of integration of the ex- 

 trapyramidal systems both of the striatum and of the cerebellum, and through 

 thus coordinating the postural with the phasic mechanisms absolute smooth- 

 ness and precision of action are made possible. "Posture," it is said, "follows 

 movement like a shadow," and this would be wholly impossible if the two were 

 not integrated from a common level. 



Other more practical considerations emerge from this concept of interaction 

 of the postural and phasic mechanisms, namely, the physiological basis for 

 surgical intervention in the cortico-striatal syndromes, and possibly, also, in 

 the cortico-cerebellar. 



The -work of Bucy and Buchanan^ (see also Bucy"^, Putnam,^ Meyers,^* and 

 particularly that of Klemme,^ has focused attention upon the possibility of 

 relieving patients afflicted with severe Parkinsonism, choreo-athetosis, hemi- 

 ballismus, etc., through a regional cortical ablation. Similarly, Aring and Ful- 

 ton"" showed experimentally that severe cerebellar tremors could be abolished 

 by precentral lesions, but, as far as I am aware, no one has attempted to apply 

 this clinically— possibly for very good reasons, namely that the motor deficit 

 would be worse than the tremor. 



In the case of severe hemichorea, and in certain cases of recalcitrant Parkin- 

 son tremors, conspicuous and apparently enduring relief has followed ablation 

 of area 4 or of area 6 from the cerebral cortex on the side opposite the affected 

 extremity. Klemme's operation necessitated making a large lesion in the pre- 

 motor region, leaving area 4 essentially intact. Bucy, on the other hand, has 

 reported"^ several excellent results from ablation of area 4 (involving only the 

 posterior few millimeters of area 6). It is not possible at present to say which is 

 the operation of choice. I feel certain that complete ablation of areas 4 and 6 

 will arrest a Parkinson tremor, a hemiathetosis or hemichorea, as well as severe 

 cerebellar tremor. Area 4-ablation will produce much the same result, as far 

 as cerebellar tremor is concerned, but there tends, with recovery of motor 

 power, to be a redevelopment of the cerebellar symptoms. This has likewise 

 proved true in certain clinical cases of hemichorea in which the symptoms 

 have ultimately returned following small precentral lesions. From the physio- 



