Motor Cortex and the Distributed Anatomy of Finger Movements

  • Marc H. Schieber
Part of the Advances in Experimental Medicine and Biology book series (AEMB, volume 508)

Abstract

Voluntary movements are thought to be controlled via a well-ordered, spatially discrete, somatotopic map in the primary motor cortex (MI). We examined this hypothesis in monkeys trained to perform visually-cued, individuated flexion and extension movements of each digit and of the wrist. Single neurone recordings in M1 during such finger movements revealed two unexpected features. First, single MI neurones often discharge during instructed movements of multiple digits. Second, neurones active during any particular instructed movement are distributed widely throughout the same M1 territory as neurones active during any other movement. Reversible, partial inactivation of the Ml hand representation produced by injection of 5-10.tg muscimol at one site impaired the monkeys’ ability to perform finger movements, but no relationship was evident between the particular finger movements that were affected and the mediolateral location of the injection site along the central sulcus. Thus each finger movement is represented by activity distributed widely in the Ml upper extremity representation. If not controlled from spatially segregated M1 regions, movements of different fingers might be controlled by groups of spatially scattered but physiologically similar neurones. Cluster analysis of M1 neurones demonstrated a large group that discharged during most finger movements, and a small group that paused during most movements. Distinct functional groups of M1 neurones that might control particular finger movements were identified inconsistently. We therefore hypothesize that M1 neurones are a very diverse network controlling finger movements.

Keywords

Hunt Muscimol 

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References

  1. Engel, K. C., Flanders, M., and Soechting, J. F., 1997, Anticipatory and sequential motor control in piano playingExperimental Brain Research 463,189–199.CrossRefGoogle Scholar
  2. Farmer S. F., Halliday, D. M., Conway, B. A., Stephens, J. A., and Rosenberg, J. R., 1997, A review of recent applications of cross-correlation methodologies to human motor unit recordingJournal of Neuroscience Methods74, 175–187.PubMedCrossRefGoogle Scholar
  3. Hager-Ross, C., and Schieber, M. H., 2000, Quantifying the independence of human finger movements: Comparisons of digits, hands, and movement frequenciesJournal of Neuroscience20, 8542–8550.PubMedGoogle Scholar
  4. Poliakov, A. V., and Schieber, M. H. 1999, Limited functional grouping of neurons in the motor cortex hand area during individuated finger movements: A cluster analysisJournal of Neurophysiology 82, 3488–3505.PubMedGoogle Scholar
  5. Schieber, M. H., 1991, Individuated finger movements of rhesus monkeys: a means of quantifying the independence of the digitsJournal of Neurophysiology65, 1381–1391.PubMedGoogle Scholar
  6. Schieber, M. H., 1995, Muscular production of individuated finger movements: The roles of extrinsic finger musclesJournal of Neuroscience15, 284–297.PubMedGoogle Scholar
  7. Schieber, M. H., Chua, M., Petit, J., and Hunt, C. C., 1997, Tension distribution of single motor units in multitendoned muscles: comparison of a homologous digit muscle in cats and monkeysJournal of Neuroscience 171734–1747.PubMedGoogle Scholar
  8. Schieber, M. H., Gardinier, J., and Liu, J., 2001, Tension distribution to the five digits of the hand by neuromuscular compartments in the macaque flexor digitorum profundusJournal of Neuroscience21, 2150–2158.PubMedGoogle Scholar
  9. Schieber, M. H., and Hibbard, L. S., 1993, How somatotopic is the motor cortex hand area?Science261, 489–492.PubMedCrossRefGoogle Scholar
  10. Schieber, M.H.,and Poliakov, A. V., 1998, Partial inactivation of the primary motor cortex hand area: effects on individuated finger movements,Journal of Neuroscience, 18, 9038–9054.PubMedGoogle Scholar
  11. Soechting, J.F., and Flanders, M., 1997, Flexibility and repeatability of finger movements during typing: analysis of multiple degrees of freedomJournal of Computational Neuroscience4, 29–46.PubMedCrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media New York 2002

Authors and Affiliations

  • Marc H. Schieber
    • 1
  1. 1.Departments of Neurology and of Neurobiology & AnatomyUniversity of Rochester School of Medicine and Dentistry RochesterNew YorkUSA

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