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New perspectives on spinal motor systems. Bizzi E, Tresch MC, Saltiel P, d'Avella A Nat Rev Neurosci 2000 Nov;1(2):101-8
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The role of the spinal cord The production and control of complex motor functions are usually attributed to central brain structures such as cortex, basal ganglia and cerebellum. In traditional schemes the spinal cord is assigned a subservient function during the production of movement, playing a predominantly passive role by relaying the commands dictated to it by supraspinal systems. This review challenges this idea by presenting evidence that the spinal motor system is an active participant in several aspects of the production of movement, contributing to functions normally ascribed to 'higher' brain regions.
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Isometric force fields Bizzi et al. 1991
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Smooth fields
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The dynamics Mussa-Ivaldi et al. 1990
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3D forcefields in the rat spinal cord
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Summation of force fields F (x 1 ) F (x 2 ) F (x 1 ) + F (x 2 ) F (x 1 +x 2 ) r > 0.9 Mussa-Ivaldi et al. 1994
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Control I: Iontophorese P. SALTIEL, M.C. TRESCH & E. BIZZI, J. Neurophysiol., 2000 Taken together, these results support the concept of a modular organization of the motor system in the frog’s spinal cord and delineate the topography of these modules. They also suggest that these modules are used by the circuitry underlying rhythmic pattern generation by the spinal cord.
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Control II: random activation r median = 0.871 Loeb et al., J. Cog. Neurosci., 2000
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Control II: random activation Only few of the random activations leed to robust synergies Loeb et al., J. Cog. Neurosci., 2000
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Control III: Dimensionality A. D’AVELLA AND E. BIZZI, PNAS, 1998
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The involvement of spinal interneurons in the preparation for movement. Y. Prut & E.E. Fetz, Nature, 1999
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A comparison of different motor structures Y. Prut & E.E. Fetz, Nature, 1999
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The process of motor adaptation following ankle extensor nerve cut
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The sensory side G. Bosco, R.E. Poppele, & J. Eian, J. Neurophysiol. 2000... We found that 14% neurons represented one or more specific joint angles. The activity of another 39% neurons was significantly affected by limb geometry changes, but 47% consistently elaborated a foot position represen- tation in the coordinates of the limb axis.
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The end
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Muscle activation patterns
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