JN Miami Valley Hospital
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

J Neurophysiol 92: 734-742, 2004. First published March 31, 2004; doi:10.1152/jn.00027.2004
0022-3077/04 $5.00
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow All Versions of this Article:
92/2/734    most recent
00027.2004v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via ISI Web of Science (10)
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Reilly, K. T.
Right arrow Articles by Schieber, M. H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Reilly, K. T.
Right arrow Articles by Schieber, M. H.

Short-Term Synchronization Between Motor Units in Different Functional Subdivisions of the Human Flexor Digitorum Profundus Muscle

Karen T. Reilly1, Michael A. Nordstrom3 and Marc H. Schieber1,2

Departments of 1Neurobiology and Anatomy and 2Neurology, University of Rochester School of Medicine and Dentistry, Rochester, New York 14642; and 3Discipline of Physiology, The University of Adelaide, Adelaide, South Australia 5005, Australia

Submitted 9 January 2004; accepted in final form 22 March 2004

The ability to independently move the digits is limited by peripheral as well as central factors. A central limitation to independent finger movements might arise from the inability of the human nervous system to activate motor units (MUs) that exert force on one finger without also activating MUs that exert force on adjacent fingers. Short-term synchronization between MU pairs is thought to be the result of the two motoneurons receiving common input from last-order neuronal projections. The human flexor digitorum profundus (FDP) muscle contains four subdivisions, one for each of the fingers. We hypothesized that the distribution of MU synchrony within and between subdivisions of FDP might parallel the ability to selectively activate different functional subdivisions within FDP, and the ability to flex one digit independently of another. We found that the degree of MU synchrony indeed was not uniform among the different functional subdivisions of FDP; MUs acting on ulnar digits (d5, d4) were more synchronized than MUs acting on radial digits (d2, d3). Furthermore, synchrony was observed between MU pairs where each unit acted on a different digit and was highest when both units of a pair acted on the least-independent digits (d4, d5). This indicates that the CNS does not exert completely independent control over the different functional subdivisions of FDP. The strength of synchrony appears related to the inability to produce completely independent forces or movements with the digits. These observations reflect widespread divergence of last-order inputs within the FDP motoneuron pool, and we suggest that the organization of the CNS drive to this muscle contributes to the limited ability of humans to flex one digit in isolation from other digits.

Address for reprint requests and other correspondence: M.H. Schieber, University of Rochester Medical Center, 601 Elmwood Ave, Box 673, Rochester, NY 14642 (E-mail: mhs{at}cvs.rochester.edu).




This article has been cited by other articles:


Home page
 J. Neurophysiol.Home page
S. A. Winges, K. W. Kornatz, and M. Santello
Common Input to Motor Units of Intrinsic and Extrinsic Hand Muscles During Two-Digit Object Hold
J Neurophysiol, March 1, 2008; 99(3): 1119 - 1126.
[Abstract] [Full Text] [PDF]

Home page
 J. Physiol.Home page
W. S. Yu, S. L. Kilbreath, R. C. Fitzpatrick, and S. C. Gandevia
Thumb and finger forces produced by motor units in the long flexor of the human thumb
J. Physiol., September 15, 2007; 583(3): 1145 - 1154.
[Abstract] [Full Text] [PDF]

Home page
 J. Neurophysiol.Home page
T. L. McIsaac and A. J. Fuglevand
Motor-Unit Synchrony Within and Across Compartments of the Human Flexor Digitorum Superficialis
J Neurophysiol, January 1, 2007; 97(1): 550 - 556.
[Abstract] [Full Text] [PDF]

Home page
 J. Neurophysiol.Home page
S. A. Winges, J. A. Johnston, and M. Santello
Muscle-Pair Specific Distribution and Grip-Type Modulation of Neural Common Input to Extrinsic Digit Flexors
J Neurophysiol, September 1, 2006; 96(3): 1258 - 1266.
[Abstract] [Full Text] [PDF]

Home page
 J. Neurophysiol.Home page
J. A. Johnston, S. A. Winges, and M. Santello
Periodic Modulation of Motor-Unit Activity in Extrinsic Hand Muscles During Multidigit Grasping
J Neurophysiol, July 1, 2005; 94(1): 206 - 218.
[Abstract] [Full Text] [PDF]

Home page
 J. Neurosci.Home page
G. B. Hockensmith, S. Y. Lowell, and A. J. Fuglevand
Common Input across Motor Nuclei Mediating Precision Grip in Humans
J. Neurosci., May 4, 2005; 25(18): 4560 - 4564.
[Abstract] [Full Text] [PDF]

Home page
 Integr. Comp. Biol.Home page
S. A. Winges and M. Santello
From Single Motor Unit Activity to Multiple Grip Forces: Mini-review of Multi-digit Grasping.
Integr. Comp. Biol., January 1, 2005; 45: 679 - 682.
[Abstract] [Full Text] [PDF]

Home page
 J. Neurophysiol.Home page
S. A. Winges and M. Santello
Common Input to Motor Units of Digit Flexors During Multi-Digit Grasping
J Neurophysiol, December 1, 2004; 92(6): 3210 - 3220.
[Abstract] [Full Text] [PDF]


HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Visit Other APS Journals Online
Copyright © 2004 by the The American Physiological Society.