Periodic modulation of motor-unit activity in extrinsic hand muscles during multidigit grasping.
We recently examined the extent to which motor units of digit flexor muscles receive common input during multidigit grasping. This task elicited moderate to strong motor-unit synchrony (common input strength, CIS) across muscles (flexor digitorum profundus, FDP, and flexor pollicis longus, FPL) and across FDP muscle compartments, although the strength of this common input was not uniform across digit pairs. To further characterize the neural mechanisms underlying the control of multidigit grasping, we analyzed the relationship between firing of single motor units from these hand muscles in the frequency domain by computing coherence. We report three primary findings. First, in contrast to what has been reported in intrinsic hand muscles, motor units belonging to different muscles and muscle compartments of extrinsic digit flexors exhibited significant coherence in the 0- to 5- and 5- to 10-Hz frequency ranges and much weaker coherence in the higher 10-20 Hz range (maximum 0.0025 and 0.0008, respectively, pooled across all FDP compartment pairs). Second, the strength and incidence of coherence differed considerably across digit pairs. Third, contrary to what has been reported in the literature, across-muscle coherence can be stronger and more prevalent than within-muscle coherence, as FPL-FDP2 (thumb-index digit pair) exhibited the strongest and most prevalent coherence in our data (0.010 and 43% at 3 Hz, respectively). The heterogeneous organization of common input to these muscles and muscle compartments is discussed in relation to the functional role of individual digit pairs in the coordination of multiple digit forces in grasping.
Johnston
Jamie A
JA
Department of Kinesiology, PEBE 107B, Orange Street, Arizona State University, Tempe, Arizona 85287-0404, USA.
Winges
Sara A
SA
Santello
Marco
M
D000200:Action Potentials / Q000502:physiology; D000328:Adult; D004558:Electric Stimulation / Q000379:methods; D004576:Electromyography / Q000379:methods; D005260:Female; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D009046:Motor Neurons / Q000502:physiology*; D018482:Muscle, Skeletal / Q000294:innervation / Q000502:physiology*; D010507:Periodicity; D013997:Time Factors
J Clin Neurophysiol. 1999 Nov;16(6):501-11
10600018
J Physiol. 1999 Dec 1;521 Pt 2:553-64
10581324
J Physiol. 1999 Nov 1;520 Pt 3:929-40
10545155
Brain. 2000 Aug;123 ( Pt 8):1545-67
10908186
Exp Brain Res. 2000 Aug;133(3):377-90
10958528
Exp Brain Res. 2000 Aug;133(4):457-67
10985681
Exp Brain Res. 2002 Mar;143(1):57-66
11907691
Exp Brain Res. 2002 May;144(1):38-49
11976758
J Physiol. 2002 Jun 15;541(Pt 3):937-48
12068052
Biol Cybern. 2002 Jul;87(1):50-7
12111268
J Physiol. 2002 Dec 1;545(Pt 2):681-95
12456843
Exp Brain Res. 2003 Jan;148(1):77-87
12478398
J Neurophysiol. 2003 Mar;89(3):1317-26
12626614
J Neurophysiol. 2003 Aug;90(2):1346-9
12904514
J Neurophysiol. 2004 Jan;91(1):57-62
12968013
J Comput Neurosci. 2004 Mar-Apr;16(2):139-57
14758063
J Neurophysiol. 2004 Feb;91(2):796-814
14586033
Exerc Sport Sci Rev. 2004 Apr;32(2):75-80
15064652
J Appl Physiol (1985). 2004 Jun;96(6):2293-300
15133016
J Neurophysiol. 2004 Aug;92(2):734-42
15056692
J Neurophysiol. 2004 Aug;92(2):790-6
15071089
Biophys J. 1970 Sep;10(9):876-900
4322240
J Neurophysiol. 1976 Mar;39(2):370-83
943474
J Physiol. 1976 Dec;263(3):357-81
1018273
Electroencephalogr Clin Neurophysiol. 1978 Aug;45(2):302-4
78843
J Neurosci Methods. 1979 Aug;1(2):107-32
161793
J Physiol. 1986 Dec;381:529-49
3625544
Prog Biophys Mol Biol. 1989;53(1):1-31
2682781
J Physiol. 1992 Mar;448:397-412
1593472
J Physiol. 1992;453:547-74
1464844
Exp Physiol. 1993 May;78(3):263-301
8329205
J Physiol. 1993 Oct;470:127-55
8308721
Exp Brain Res. 1993;97(1):159-72
8131826
Exp Brain Res. 2003 Sep;152(2):173-84
12898101
Neurosci Lett. 1994 Mar 28;170(1):94-8
8041521
Trends Neurosci. 1994 Jul;17(7):299-305
7524216
J Comput Neurosci. 1994 Jun;1(1-2):11-38
8792223
J Neurosci Methods. 1997 Apr 25;73(1):69-79
9130680
J Neurosci Methods. 1997 Jun 27;74(2):175-87
9219887
Brain Res. 1997 Sep 5;767(2):314-20
9367263
J Physiol. 1998 May 15;509 ( Pt 1):3-14
9547376
J Neurosci Methods. 1998 Aug 31;83(1):57-72
9765051
J Neurophysiol. 1999 Apr;81(4):1706-17
10200206
J Comput Neurosci. 1999 May-Jun;6(3):289-310
10406139
J Neurophysiol. 1999 Aug;82(2):664-75
10444664
Exp Brain Res. 1999 Sep;128(1-2):109-17
10473748
J Neurophysiol. 2004 Dec;92(6):3210-20
15240764
J Neurophysiol. 2004 Dec;92(6):3320-31
15269232
Exp Brain Res. 2004 Dec;159(4):501-8
15558252
Neural Comput. 2000 Mar;12(3):693-707
10769327