9o8 



HANDBOOK OF PHYSIOLOGY 



NEUROPHYSIOLOGY II 



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HG. 15. Bilateral parkinsonian 

 tremor in man (a to d) and fin 

 movements of fishes (e and /) 

 illustrating the 'relative ro- 

 ordination' of von Hoist. The 

 rhythmic movements of the two 

 sides are independent at the 

 start of each record and later 

 show different coordination phe- 



L Foot 



Focus (leading rhythm) left 

 Dependent rhythm right 



Dependent rhythm left 

 Focus right 



1| 



jndent rhythm ngnt . v-^^.^ . .y. . 



thor fin 



thoroc fin J* 



nomena varying in short time 

 intervals, a: Phase coordination 

 (von Hoist's 'magnet effect') 

 with a tendency to phase reversal 

 and alternating movements of the 

 two sides. ^, an intermediate beat 

 (^wische>t\chlag) with double 

 peak, +, beats with larger amplitude and phase 

 reversal; 0, absolute phase coordination with 

 slight slowing of right foot, i: Independent ac- 

 tion of both rhythms, c: Central superposition. 

 Diminished amplitude of left foot (~) when both 

 rhythms show phase re%'ersal, and larger ampli- 

 tude ( + ) when they are beating in phase, d: 

 Variation of dominant focus. The dominant 

 rhythm in the region of the focus is more regular 

 and of larger amplitude. The other (dependent) 

 rhythm shows irregularities and lower ampli- 

 tudes. B, short blocking of rhythm, f: Periodicity 

 of phase coordination in fin movement. ^, inter- 

 mediate beat and its development from the original rhythm ( ) by attraction of reversed 

 phases ( I ); 0, absolute phase coordination similar to human tremor in a. /: Amplitude varia- 

 tions of dorsal fin movements similar to human tremor in c. [From Jung (130, 133)-] 



bulbospinal .system. As all bulbospinal intcrneuronal 

 systems receive propriocepti\e input, it did not seem 

 surprising that some reflex mechanisms would also 

 interfere with tremor. But, as VValshe (289) had shown 

 in 1924, tremor rhythms are usually independent of 

 reflex mechanisms and proprioceptive influx, whereas 

 rigidity disappears after novocainization of muscles. 

 The mechanism of this procaine effect, however, 

 cannot be a pure blocking of proprioceptive influx 

 as Liljestrand & Magnus (162) assumed since cocain- 

 ization inactivates efferent gamma fibers before the 

 large fibers of proprioceptive afferents are affected 

 [Leksell (158), Matthews & Rushworth (17B)]. The 

 effects of stereotaxic operations in man show a diminu- 

 tion of tremor following thalamic and pallidal lesions. 

 Therefore, a facilitative influence of these cerebral 

 structures upon the lower mechanisms of tremor 

 movements has to be assumed (see also p. 885). 



Hyperki 



in General 



A general explanation of extrapyramidal hyper- 

 kineses can be drawn from Hess' conceptions (106- 



108) of a physiological balance of several direction- 

 specific "forces" in motor and postural regulation: if 

 the regulation of movements results from a delicate 

 balance of several forces, oriented in the three dimen- 

 sions of space, a lesion in one of these regulation 

 centers should induce oppositelv directed mo\ements. 

 The muscular contractions in these movements may 

 be either tonic as in torsion dystonia, torticollis and 

 partly in athetosis, or intermittent as in chorea and 

 hemiballism. There is a remarkalile parallel between 

 the tonic dexiations of Hess' cats and certain extra- 

 pyramidal svndromes in man in that both are appar- 

 ent only in the waking state with acti\e postural back- 

 ground innervation and that they are induced or 

 increased by active movements and emotional ten- 

 sion. Generallv the movements should be the mirror 

 irnage or opposite of the stimulation effects caused by 

 a release of the forces of inner\ation normally bal- 

 anced by the damaged center. This is indeed the case 

 in midbrain lesions as shown in figure 10. Such an 

 explanation was first used b\ Monnier {192) for 

 torticollis as a result of Hess' findings. It is in agree- 

 ment with Jackson's classical explanation of positive 



