Organization of common synaptic drive to motoneurones during fictive locomotion in the spinal cat
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Organization of common synaptic drive to motoneurones during fictive locomotion in the spinal cat. / Nielsen, Jens Bo; Conway, B.A.; Halliday, D.M.; Perreault, M.-C.; Hultborn, Hans Rurik Albert.
I: Journal of Physiology, Bind 569, Nr. 1, 2005, s. 291-304.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Organization of common synaptic drive to motoneurones during fictive locomotion in the spinal cat
AU - Nielsen, Jens Bo
AU - Conway, B.A.
AU - Halliday, D.M.
AU - Perreault, M.-C.
AU - Hultborn, Hans Rurik Albert
N1 - PUF 2005 5200 030
PY - 2005
Y1 - 2005
N2 - The basic locomotor rhythm in the cat is generated by a neuronal network in the spinal cord. The exact organization of this network and its drive to the spinal motoneurones is unknown. The purpose of the present study was to use time (cumulant density) and frequency domain (coherence) analysis to examine the organization of the last order drive to motoneurones during fictive locomotion (evoked by application of nialamide and dihydroxyphenylalanine (DOPA)) in the spinal cat. In all cats, narrow central synchronization peaks (half-width < 3 ms) were observed in cumulants estimated between electroneurograms (ENGs) of close synergists, but not between nerves belonging to muscles acting on different joints or to antagonistic muscles. Coherence was not observed at frequencies above 100 Hz and was mainly observed between synergists. Intracellular recording was obtained from a population of 70 lumbar motoneurones. Significant short-term synchronization was observed between the individual intracellular recordings and the ENGs recorded from nerves of the same pool and of close synergists. Recordings from 34 pairs of motoneurones (10 pairs belonged to the same motor pool, 11 pairs to close synergists and 13 pairs to antagonistic pools) failed to reveal any short-lasting synchronization. These data demonstrate that short-term synchronization during fictive locomotion is relatively weak and is restricted to close synergists. In addition, coherence analysis failed to identify any specific rhythmic component in the locomotor drive that could be associated with this synchronization. These results resemble findings obtained during human treadmill walking and imply that the spinal interneurones participating in the generation of the locomotor rhythm are themselves weakly synchronized. The restricted synchronization within the locomotor drive to motoneuronal pools may be a feature of the locomotor generating networks that is related to the ability of these networks to produce highly adaptive patterns of muscle activity during locomotion.
AB - The basic locomotor rhythm in the cat is generated by a neuronal network in the spinal cord. The exact organization of this network and its drive to the spinal motoneurones is unknown. The purpose of the present study was to use time (cumulant density) and frequency domain (coherence) analysis to examine the organization of the last order drive to motoneurones during fictive locomotion (evoked by application of nialamide and dihydroxyphenylalanine (DOPA)) in the spinal cat. In all cats, narrow central synchronization peaks (half-width < 3 ms) were observed in cumulants estimated between electroneurograms (ENGs) of close synergists, but not between nerves belonging to muscles acting on different joints or to antagonistic muscles. Coherence was not observed at frequencies above 100 Hz and was mainly observed between synergists. Intracellular recording was obtained from a population of 70 lumbar motoneurones. Significant short-term synchronization was observed between the individual intracellular recordings and the ENGs recorded from nerves of the same pool and of close synergists. Recordings from 34 pairs of motoneurones (10 pairs belonged to the same motor pool, 11 pairs to close synergists and 13 pairs to antagonistic pools) failed to reveal any short-lasting synchronization. These data demonstrate that short-term synchronization during fictive locomotion is relatively weak and is restricted to close synergists. In addition, coherence analysis failed to identify any specific rhythmic component in the locomotor drive that could be associated with this synchronization. These results resemble findings obtained during human treadmill walking and imply that the spinal interneurones participating in the generation of the locomotor rhythm are themselves weakly synchronized. The restricted synchronization within the locomotor drive to motoneuronal pools may be a feature of the locomotor generating networks that is related to the ability of these networks to produce highly adaptive patterns of muscle activity during locomotion.
U2 - 10.1113/jphysiol.2005.091744
DO - 10.1113/jphysiol.2005.091744
M3 - Journal article
C2 - 16166163
VL - 569
SP - 291
EP - 304
JO - The Journal of Physiology
JF - The Journal of Physiology
SN - 0022-3751
IS - 1
ER -
ID: 89821