9i6 



HANDBOOK OF PHYSIOLOGY 



NEUROPHYSIOLOGY II 



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FIG. 20, Spontaneous rotatory movements of cats as integral 

 parts of instincti\e behavior, a to i: Sudden rotation of a de- 

 fendins; male cat during fight, k: Slower rotatory turning move- 

 ments of a female cat in heat during sexual play before mating. 

 The head precedes a clockwise rotation and rolling movement. 

 [From Leyhausen (160).] 



there was little spontaneous activity. Left alone the 

 anencephalus remained mostly in a drowsy state from 

 which it could be aroused by sensory stimuli. 



Rolling movements are integral parts of certain 

 types of instinctive behavior, such as appear in male 

 cats fighting each other or in female cats during 

 sexual play. Examples taken from the studies of 

 Leyhausen (160) appear in figure 20. These move- 

 ments are doubtless similar in nature to the rotatory 

 movements of the head arid body which Hess ob- 

 tained in cats by stimulation of the diencephalon. 



(fig. 10). Their appearance in instinctive activitv ap- 

 parently depends on emotional release. 



Very little is known about the role of the extra- 

 pyramidal motor system in conditioned behavior. 

 Stevens & MacLean (manuscript in preparation) 

 found that low-frequency stimulation of the caudate 

 nucleus in cats caused a failure of conditioned 

 avoidance responses whereas high-frequency stimula- 

 tion caused circling but did not alter the conditioned 

 reaction. Brady (13) observed elimination of condi- 

 tioned fear responses when cats indulged in .self- 

 stimulation of the caudate nucleus. Recent experi- 

 mental evidence has shown an important role for the 

 nonspecific acti\'ation system in conditioned re- 

 spon.ses. 



Enddirhie Influenci's on Extrap\ramidal Mechanisms 



That the extrapyramidal motor centers are related 

 to the endocrine system is indicated by some clinical 

 and experimental observations, but their mechanism 

 is still obscure. An influence of the sex hormones was 

 suggested by the observation of Simons (235) that 

 tonic neck reflexes in a female hemiplegic were 

 diminished or abolished during menstruation. Olds 

 (203) obser\ed that in self-stimulation experiments 

 with electrodes in the caudate nucleus, castrate rats 

 responded only when the androgen le\'el was kept 

 adequate. C^lear experimental evidence for hormonal 

 action on extrapyramidal structures is available only 

 for lower pontobulbar centers. Dell et al. (38) have 

 established the activating influence of epinephrine on 

 the reticular formation. A clinical parallel may be the 

 increase in the tremor of Parkinson's disease pro- 

 duced by epinephrine, as described by Barcroft et al. 

 (11). The physiological meaning of these interesting 

 and puzzling observations still remains to be investi- 

 gated. 



Electrophysiology of Basal Ganglia 



As stated above, the application of classical methods 

 of localized stimulation and extirpation to the basal 

 ganglia in animals was rather disappointing. New 

 hope for experimental investigation of basal ganglia 

 arose when the recording of brain potentials was then 

 applied to the extrapyramidal system in the deeper 

 brain structures. However, information so obtained 

 has been rather limited and its physiological interpre- 

 tation not very illuminating. 



Gerard et al. (68) first used the Horsley-Clarke 

 apparatus for picking up potentials from \arious 



