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. 1981;313:317–334. doi: 10.1113/jphysiol.1981.sp013667

Motor unit firing and its relation to tremor in the tonic vibration reflex of the decerebrate cat.

F J Clark, P B Matthews, R B Muir
PMCID: PMC1274453  PMID: 7277222

Abstract

1. The discharge of single motor units has been recorded from the soleus muscle of the decerebrate cat during the tonic vibration reflex elicited isometrically, to further understanding of the tremor that is seen in the reflex contraction. The reflex was elicited by pulses of vibration of 50 micrometers amplitude at 150 Hz, and up to four units were studied concurrently. 2. Individual units fired rather regularly and at a low frequency (range 4-14 Hz). The rate of firing of any unit normally fell within the frequency band of the tremor recorded at the same time. On comparing different preparations a higher frequency of tremor was associated with a higher frequency of motor firing. 3. The responses of pairs of motor units recorded concurrently during repeated production of the reflex were compared by cross-correlation analysis; over 1000 spikes from each train were normally used for this. The major of the cross-correlograms were flat with no overt sign of any synchronization between the units other than that due to the vibration. 4. Clear indications of correlated motor unit firing could be produced deliberately by modulating the amplitude of vibration at a frequency comparable to that of the normal tremor and thereby introducing a rhythmic component into the tonic vibration reflex. 5. About 20% of the cross-correlograms obtained during normal tremor showed varying amounts of an irregular 'waviness' suggesting a possible correlation between the times of firing of a pair of units. But such waves never developed steadily throughout the period of analysis, in contrast to the comparable waves produced on modulating the vibration. Similar waves were seen on cross-correlating a motor unit with an electronic oscillator, confirming that their occurrence does not necessarily demonstrate the existence of active neural interactions. 6. It is concluded that there is no strong and widespread neural synchronizing mechanism active during the tonic vibration reflex, although the possibility of some weak neural interactions has not been excluded. The findings favour the idea that the tremor in this preparation is simply the inevitable result of motor units discharging asynchronously, but at closely similar subtetanic frequencies.

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Selected References

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  1. Allum J. H., Dietz V., Freund H. J. Neuronal mechanisms underlying physiological tremor. J Neurophysiol. 1978 May;41(3):557–571. doi: 10.1152/jn.1978.41.3.557. [DOI] [PubMed] [Google Scholar]
  2. Christakos C. N., Lal S. Lumped and population stochastic models of skeletal muscle: implications and predictions. Biol Cybern. 1980;36(2):73–85. doi: 10.1007/BF00361076. [DOI] [PubMed] [Google Scholar]
  3. Clark F. J., Matthews P. B., Muir R. B. Response of soleus Ia afferents to vibration in the presence of the tonic vibration reflex in the decerebrate cat. J Physiol. 1981 Feb;311:97–112. doi: 10.1113/jphysiol.1981.sp013575. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Cussons P. D., Matthews P. B., Muir R. B. Tremor in the tension developed isometrically by soleus during the tonic vibration reflex in the decerebrate cat. J Physiol. 1979 Jul;292:35–57. doi: 10.1113/jphysiol.1979.sp012837. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Homma S., Kanda K., Watanabe S. Monosynaptic coding of group Ia afferent discharges during vibratory stimulation of muscles. Jpn J Physiol. 1971 Aug;21(4):405–417. doi: 10.2170/jjphysiol.21.405. [DOI] [PubMed] [Google Scholar]
  6. Korkala O., Eränkö O., Partanen S., Eränkö L., Hervonen A. Histochemically demonstrable increase in the catecholamine content of the carotid body in adult rats treated with methylprednisolone or hydrocortisone. Histochem J. 1973 Sep;5(5):479–485. doi: 10.1007/BF01012005. [DOI] [PubMed] [Google Scholar]
  7. Llados F., Zapata P. Effects of dopamine analogues and antagonists on carotid body chemosensors in situ. J Physiol. 1978 Jan;274:487–499. doi: 10.1113/jphysiol.1978.sp012162. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Lundberg J. M., Hökfelt T., Fahrenkrug J., Nilsson G., Terenius L. Peptides in the cat carotid body (glomus caroticum): VIP-, enkephalin-, and substance P-like immunoreactivity. Acta Physiol Scand. 1979 Nov;107(3):279–281. doi: 10.1111/j.1748-1716.1979.tb06475.x. [DOI] [PubMed] [Google Scholar]
  9. Matthews P. B., Muir R. B. Comparison of electromyogram spectra with force spectra during human elbow tremor. J Physiol. 1980 May;302:427–441. doi: 10.1113/jphysiol.1980.sp013254. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Matthews P. B. The dependence of tension upon extension in the stretch reflex of the soleus muscle of the decerebrate cat. J Physiol. 1959 Oct;147(3):521–546. doi: 10.1113/jphysiol.1959.sp006260. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Matthews P. B. The relative unimportance of the temporal pattern of the primary afferent input in determining the mean level of motor firing in the tonic vibration reflex. J Physiol. 1975 Oct;251(2):333–361. doi: 10.1113/jphysiol.1975.sp011096. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. McCloskey D. I. Mechanisms of autonomic control of carotid chemoreceptor activity. Respir Physiol. 1975 Oct;25(1):53–61. doi: 10.1016/0034-5687(75)90050-x. [DOI] [PubMed] [Google Scholar]
  13. McQueen D. S. Effects of substance P on carotid chemoreceptor activity in the cat. J Physiol. 1980 May;302:31–47. doi: 10.1113/jphysiol.1980.sp013228. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Mills E., Smith P. G., Slotkin T. A., Breese G. Role of carotid body catecholamines in chemoreceptor function. Neuroscience. 1978;3(12):1137–1146. doi: 10.1016/0306-4522(78)90134-3. [DOI] [PubMed] [Google Scholar]
  15. Neil E., O'Regan R. G. The effects of electrical stimulation of the distal end of the cut sinus and aortic nerves on peripheral arterial chemoreceptor activity in the cat. J Physiol. 1971 May;215(1):15–32. doi: 10.1113/jphysiol.1971.sp009455. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. O'Regan R. G. Carotid chemoreceptor responses to sympathetic excitation [proceedings]. J Physiol. 1976 Dec;263(2):267P–268P. [PubMed] [Google Scholar]
  17. Perkel D. H., Gerstein G. L., Moore G. P. Neuronal spike trains and stochastic point processes. II. Simultaneous spike trains. Biophys J. 1967 Jul;7(4):419–440. doi: 10.1016/S0006-3495(67)86597-4. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Purves M. J. The effect of hypoxia, hypercapnia and hypotension upon carotid body blood flow and oxygen consumption in the cat. J Physiol. 1970 Aug;209(2):395–416. doi: 10.1113/jphysiol.1970.sp009171. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Purves M. J. The role of the cervical sympathetic nerve in the regulation of oxygen consumption of the carotid body of the cat. J Physiol. 1970 Aug;209(2):417–431. doi: 10.1113/jphysiol.1970.sp009172. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Rack P. M., Westbury D. R. The effects of length and stimulus rate on tension in the isometric cat soleus muscle. J Physiol. 1969 Oct;204(2):443–460. doi: 10.1113/jphysiol.1969.sp008923. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Said S. I., Mutt V. Polypeptide with broad biological activity: isolation from small intestine. Science. 1970 Sep 18;169(3951):1217–1218. doi: 10.1126/science.169.3951.1217. [DOI] [PubMed] [Google Scholar]
  22. Sampson S. R., Aminoff M. J., Jaffe R. A., Vidruk E. H. Analysis of inhibitory effect of dopamine on carotid body chemoreceptors in cats. Am J Physiol. 1976 Jun;230(6):1494–1498. doi: 10.1152/ajplegacy.1976.230.6.1494. [DOI] [PubMed] [Google Scholar]
  23. Sampson S. R. Mechanism of efferent inhibition of carotid body chemoreceptors in the cat. Brain Res. 1972 Oct 13;45(1):266–270. doi: 10.1016/0006-8993(72)90236-3. [DOI] [PubMed] [Google Scholar]
  24. TAYLOR A. The significance of grouping of motor unit activity. J Physiol. 1962 Jul;162:259–269. doi: 10.1113/jphysiol.1962.sp006930. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Verna A. Ulstrastructure of the carotid body in the mammals. Int Rev Cytol. 1979;60:271–330. doi: 10.1016/s0074-7696(08)61265-6. [DOI] [PubMed] [Google Scholar]
  26. Vázquez-Nin G. H., Costero I., Echeverría O. M., Aguilar R., Barroso-Moguel R. Innervation of the carotid body. An experimental quantitative study. Acta Anat (Basel) 1978;102(1):12–28. doi: 10.1159/000145613. [DOI] [PubMed] [Google Scholar]
  27. Wharton J., Polak J. M., Pearse A. G., McGregor G. P., Bryant M. G., Bloom S. R., Emson P. C., Bisgard G. E., Will J. A. Enkephalin-, VIP- and substance P-like immunoreactivity in the carotid body. Nature. 1980 Mar 20;284(5753):269–271. doi: 10.1038/284269a0. [DOI] [PubMed] [Google Scholar]
  28. Zapata P. Effects of dopamine on carotid chemo- and baroreceptors in vitro. J Physiol. 1975 Jan;244(1):235–251. doi: 10.1113/jphysiol.1975.sp010794. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Zapata P., Hess A., Bliss E. L., Eyzaguirre C. Chemical, electron microscopic and physiological observations on the role of catecholamines in the carotid body. Brain Res. 1969 Jul;14(2):473–496. doi: 10.1016/0006-8993(69)90123-1. [DOI] [PubMed] [Google Scholar]

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