Skip to main content
PMC home page
The Journal of Physiology logoLink to The Journal of Physiology
. 1991 Oct;442:585–599. doi: 10.1113/jphysiol.1991.sp018810

Independent digit control: failure to partition perceived heaviness of weights lifted by digits of the human hand.

S L Kilbreath 1, S C Gandevia 1
PMCID: PMC1179906  PMID: 1798044

Abstract

1. A weight-matching task was used to investigate the ability to estimate heaviness when weight lifting was isolated to the extrinsic flexor muscles (or portions thereof) that act on the digits of the hand. 2. Subjects matched a reference weight (200 g) lifted by a digit on the right with a variable weight lifted by the left thumb; a concurrent weight was simultaneously lifted by a digit on the right (reference) side. The reference and concurrent weights were lifted either by the same muscle (digital portions of flexor digitorum profundus), or anatomically separate but functionally related muscles (flexor digitorum profundus and flexor pollicis longus). Anaesthesia of the radial nerve and/or posturing of the hand was used to eliminate any small forces generated by co-contraction of the extensor muscles of the digits. 3. When the concurrent weight was equal to or greater than the reference weight, the perceived heaviness of the reference weight increased significantly from control trials (in which no concurrent weight was lifted). Although perceived heaviness of the reference weight increased progressively as the concurrent weight increased, reproducibility (expressed as the coefficient of variation) did not deteriorate when a weight was lifted concurrently. These findings were qualitatively similar when the reference and concurrent weights were lifted by two digital portions of flexor digitorum profundus or when the weights were lifted by flexion of the thumb and index finger. Also, anaesthesia of the digits which lifted the reference and concurrent weights did not alter the changes in perceived heaviness. 4. Perceived heaviness of the reference weight lifted by flexor digitorum profundus did not change when subjects lifted the concurrent weight with a remote muscle group (ankle dorsiflexors). 5. This study shows that signals of heaviness are systematically overestimated whenever more than one portion of the extrinsic muscles which flex the different digits are simultaneously active. Given that estimates of heaviness are biased by the central motor command, one explanation is that when the total motor drive increases, the central nervous system is unable to partition precisely the destination of motor commands to functionally related 'muscles'.

Full text

PDF
585

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Adams R. W., Gandevia S. C., Skuse N. F. The distribution of muscle weakness in upper motoneuron lesions affecting the lower limb. Brain. 1990 Oct;113(Pt 5):1459–1476. doi: 10.1093/brain/113.5.1459. [DOI] [PubMed] [Google Scholar]
  2. Aniss A. M., Gandevia S. C., Milne R. J. Changes in perceived heaviness and motor commands produced by cutaneous reflexes in man. J Physiol. 1988 Mar;397:113–126. doi: 10.1113/jphysiol.1988.sp016991. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Bigland-Ritchie B. R., Dawson N. J., Johansson R. S., Lippold O. C. Reflex origin for the slowing of motoneurone firing rates in fatigue of human voluntary contractions. J Physiol. 1986 Oct;379:451–459. doi: 10.1113/jphysiol.1986.sp016263. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Buys E. J., Lemon R. N., Mantel G. W., Muir R. B. Selective facilitation of different hand muscles by single corticospinal neurones in the conscious monkey. J Physiol. 1986 Dec;381:529–549. doi: 10.1113/jphysiol.1986.sp016342. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Cafarelli E., Bigland-Ritchie B. Sensation of static force in muscles of different length. Exp Neurol. 1979 Sep;65(3):511–525. doi: 10.1016/0014-4886(79)90040-2. [DOI] [PubMed] [Google Scholar]
  6. Cafarelli E. Force sensation in fresh and fatigued human skeletal muscle. Exerc Sport Sci Rev. 1988;16:139–168. [PubMed] [Google Scholar]
  7. Cheney P. D., Fetz E. E. Comparable patterns of muscle facilitation evoked by individual corticomotoneuronal (CM) cells and by single intracortical microstimuli in primates: evidence for functional groups of CM cells. J Neurophysiol. 1985 Mar;53(3):786–804. doi: 10.1152/jn.1985.53.3.786. [DOI] [PubMed] [Google Scholar]
  8. Clough J. F., Kernell D., Phillips C. G. The distribution of monosynaptic excitation from the pyramidal tract and from primary spindle afferents to motoneurones of the baboon's hand and forearm. J Physiol. 1968 Sep;198(1):145–166. doi: 10.1113/jphysiol.1968.sp008598. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Fritz N., Illert M., de la Motte S., Reeh P., Saggau P. Pattern of monosynaptic Ia connections in the cat forelimb. J Physiol. 1989 Dec;419:321–351. doi: 10.1113/jphysiol.1989.sp017875. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Gandevia S. C., Kilbreath S. L. Accuracy of weight estimation for weights lifted by proximal and distal muscles of the human upper limb. J Physiol. 1990 Apr;423:299–310. doi: 10.1113/jphysiol.1990.sp018023. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Gandevia S. C., Macefield G., Burke D., McKenzie D. K. Voluntary activation of human motor axons in the absence of muscle afferent feedback. The control of the deafferented hand. Brain. 1990 Oct;113(Pt 5):1563–1581. doi: 10.1093/brain/113.5.1563. [DOI] [PubMed] [Google Scholar]
  12. Gandevia S. C., McCloskey D. I. Changes in motor commands, as shown by changes in perceived heaviness, during partial curarization and peripheral anaesthesia in man. J Physiol. 1977 Nov;272(3):673–689. doi: 10.1113/jphysiol.1977.sp012066. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Gandevia S. C., McCloskey D. I. Effects of related sensory inputs on motor performances in man studied through changes in perceived heaviness. J Physiol. 1977 Nov;272(3):653–672. doi: 10.1113/jphysiol.1977.sp012065. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Gandevia S. C., McCloskey D. I. Interpretation of perceived motor commands by reference to afferent signals. J Physiol. 1978 Oct;283:493–499. [PMC free article] [PubMed] [Google Scholar]
  15. Gandevia S. C., McCloskey D. I. Joint sense, muscle sense, and their combination as position sense, measured at the distal interphalangeal joint of the middle finger. J Physiol. 1976 Sep;260(2):387–407. doi: 10.1113/jphysiol.1976.sp011521. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Gandevia S. C., McCloskey D. I., Potter E. K. Alterations in perceived heaviness during digital anaesthesia. J Physiol. 1980 Sep;306:365–375. doi: 10.1113/jphysiol.1980.sp013402. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Gandevia S. C., McCloskey D. I. Sensations of heaviness. Brain. 1977 Jun;100(2):345–354. doi: 10.1093/brain/100.2.345. [DOI] [PubMed] [Google Scholar]
  18. Gandevia S. C., Rothwell J. C. Knowledge of motor commands and the recruitment of human motoneurons. Brain. 1987 Oct;110(Pt 5):1117–1130. doi: 10.1093/brain/110.5.1117. [DOI] [PubMed] [Google Scholar]
  19. Gandevia S. C. The perception of motor commands or effort during muscular paralysis. Brain. 1982 Mar;105(Pt 1):151–159. doi: 10.1093/brain/105.1.151. [DOI] [PubMed] [Google Scholar]
  20. Hagbarth K. E., Kunesch E. J., Nordin M., Schmidt R., Wallin E. U. Gamma loop contributing to maximal voluntary contractions in man. J Physiol. 1986 Nov;380:575–591. doi: 10.1113/jphysiol.1986.sp016303. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Jones L. A. Motor illusions: what do they reveal about proprioception? Psychol Bull. 1988 Jan;103(1):72–86. doi: 10.1037/0033-2909.103.1.72. [DOI] [PubMed] [Google Scholar]
  22. Jones L. A. Role of central and peripheral signals in force sensation during fatigue. Exp Neurol. 1983 Aug;81(2):497–503. doi: 10.1016/0014-4886(83)90278-9. [DOI] [PubMed] [Google Scholar]
  23. Kasser R. J., Cheney P. D. Characteristics of corticomotoneuronal postspike facilitation and reciprocal suppression of EMG activity in the monkey. J Neurophysiol. 1985 Apr;53(4):959–978. doi: 10.1152/jn.1985.53.4.959. [DOI] [PubMed] [Google Scholar]
  24. Loo C. K., McCloskey D. I. Effects of prior instruction and anaesthesia on long-latency responses to stretch in the long flexor of the human thumb. J Physiol. 1985 Aug;365:285–296. doi: 10.1113/jphysiol.1985.sp015772. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Marsden C. D., Merton P. A., Morton H. B. Stretch reflex and servo action in a variety of human muscles. J Physiol. 1976 Jul;259(2):531–560. doi: 10.1113/jphysiol.1976.sp011481. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Marsden C. D., Rothwell J. C., Traub M. M. Effect of thumb anaesthesia on weight perception, muscle activity and the stretch reflex in man. J Physiol. 1979 Sep;294:303–315. doi: 10.1113/jphysiol.1979.sp012931. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Matthews P. B., Miles T. S. On the long-latency reflex responses of the human flexor digitorum profundus. J Physiol. 1988 Oct;404:515–534. doi: 10.1113/jphysiol.1988.sp017303. [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. McCloskey D. I., Ebeling P., Goodwin G. M. Estimation of weights and tensions and apparent involvement of a "sense of effort". Exp Neurol. 1974 Jan;42(1):220–232. doi: 10.1016/0014-4886(74)90019-3. [DOI] [PubMed] [Google Scholar]
  29. Panizza M., Lelli S., Hallett M. H-reflex in nonhomonymous muscles in the human forearm. Neurology. 1989 Jun;39(6):785–788. doi: 10.1212/wnl.39.6.785. [DOI] [PubMed] [Google Scholar]

Articles from The Journal of Physiology are provided here courtesy of The Physiological Society

RESOURCES