Timing of Muscle Activation in a Hand Movement Sequence

Breteler, Mary D. Klein; Simura, Katarzyna J.; Flanders, Martha

doi:10.1093/cercor/bhk033

Cited by 69 publications

(60 citation statements)

References 38 publications

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“…6d) the A-F sequence. Using patchy redundant somatotopy to construct movement had been suggested for spinal cord (Székely and Czéh 1971) and cortex (Klein Breteler et al 2007). …”

Section: Topography Of Synergiesmentioning

confidence: 99%

Synergy temporal sequences and topography in the spinal cord: evidence for a traveling wave in frog locomotion

et al. 2015

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Locomotion is produced by a central pattern generator. Its spinal cord organization is generally considered to be distributed, with more rhythmogenic rostral lumbar segments. While this produces a rostrocaudally traveling wave in undulating species, this is not thought to occur in limbed vertebrates, with the exception of the interneuronal traveling wave demonstrated in fictive cat scratching (Cuellar et al. J Neurosci 29:798-810, 2009). Here, we reexamine this hypothesis in the frog, using the seven muscle synergies A to G previously identified with intraspinal NMDA (Saltiel et al. J Neurophysiol 85:605-619, 2001). We find that locomotion consists of a sequence of synergy activations (A-B-G-A-F-E-G). The same sequence is observed when focal NMDA iontophoresis in the spinal cord elicits a caudal extensionlateral force-flexion cycle (flexion onset without the C synergy). Examining the early NMDA-evoked motor output at 110 sites reveals a rostrocaudal topographic organization of synergy encoding by the lumbar cord. Each synergy is preferentially activated from distinct regions, which may be multiple, and partially overlap between different synergies. Comparing the sequence of synergy activation in locomotion with their spinal cord topography suggests that the locomotor output is achieved by a rostrocaudally traveling wave of activation in the swing-stance cycle. A two-layer circuitry model, based on this topography and a traveling wave reproduces this output and explores its possible modifications under different afferent inputs. Our results and simulations suggest that a rostrocaudally traveling wave of excitation takes advantage of the topography of interneuronal regions encoding synergies, to activate them in the proper sequence for locomotion.

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“…6d) the A-F sequence. Using patchy redundant somatotopy to construct movement had been suggested for spinal cord (Székely and Czéh 1971) and cortex (Klein Breteler et al 2007). …”

Section: Topography Of Synergiesmentioning

confidence: 99%

Synergy temporal sequences and topography in the spinal cord: evidence for a traveling wave in frog locomotion

et al. 2015

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“…Recently, results from many areas have demonstrated that the activity of muscle synergies can be correlated to functional outputs related to task performance [1,7,18,19]. During standing balance control, a small set of muscle synergies can be identified that coactivate muscles throughout the limbs and trunk.…”

Section: Muscle Synergiesmentioning

confidence: 99%

“…In motor control, task-level goals such as moving the hand to a target, walking through a door, or orienting the body with respect to gravity must be translated into complex muscle activation patterns that produce the movement. Studies of motor systems ranging from those of invertebrates to those of humans suggest that the nervous system uses flexible combinations of just a few muscle synergies-the elements from which complex muscle activation patterns are constructed-to produce a wide range of motor behaviors [1,2,3•,4•,5•,6]. We define a muscle synergy to be a vector specifying relative levels of muscle activation (cf.…”

Section: Introductionmentioning

confidence: 99%

Neuromechanics of muscle synergies for posture and movement

Ting

McKay

2007

Current Opinion in Neurobiology

383

251

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Recent research suggests that the nervous system controls muscles by activating flexible combinations of muscle synergies to produce a wide repertoire of movements. Muscle synergies are like building blocks, defining characteristic patterns of activation across multiple muscles that may be unique to each individual, but perform similar functions. The identification of muscle synergies has strong implications for the organization and structure of the nervous system, providing a mechanism by which task-level motor intentions are translated into detailed, low-level muscle activation patterns. Understanding the complex interplay between neural circuits and biomechanics that give rise to muscle synergies will be critical to advancing our understanding of neural control mechanisms for movement.

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“…5). A previous adaptation of PCA to human kinematics (Santello et al, 2002) and EMG (Klein Breteler et al, 2006) similarly solves for PCs involving nonsynchronous relations between joints or muscles, but does not allow for independent temporal shifting of the synergies themselves. Such independent delays appear to be a feature of human reaching and of the results presented here, as evidenced by modulation of synergy onset times as a function of object properties (Fig.…”

Section: Data Reconstruction By Time-varying Synergiesmentioning

confidence: 99%

“…In particular, we included a wide array of objects, and had the monkeys perform a sequence of naturalistic reach, grasp, and transport movements with each. Although we did not train the animals to produce distinct hand postures (Klein Breteler et al, 2006), our design enabled us to systematically investigate the modulation of muscle synergies as a function of object shape and size.…”

Section: Introductionmentioning

confidence: 99%

Modulation of Muscle Synergy Recruitment in Primate Grasping

Overduin¹,

d’Avella²,

Roh³

et al. 2008

J. Neurosci.

174

150

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In grasping, the CNS controls a particularly large number of degrees of freedom. We tested the idea that this control is facilitated by the presence of muscle synergies. According to the strong version of this concept, these synergies are invariant, hard-wired patterns of activation across muscles. Synergies may serve as modules that linearly sum, each with specific amplitude and timing coefficients, to generate a large array of muscle patterns. We tested two predictions of the synergy model. A small number of synergies should (1) account for a large fraction of variation in muscle activity, and (2) be modulated in their recruitment by task variables, even in novel behavioral contexts. We also examined whether the synergies would (3) have broadly similar structures across animals. We recorded from 15 to 19 electrodes implanted in forelimb muscles of two rhesus macaques as they grasped and transported 25 objects of variable shape and size. We show that three synergies accounted for 81% of the electromyographic data variation in each monkey. Each synergy was modulated in its recruitment strength and/or timing by object shape and/or size. Even when synergies were extracted from a small subset of object shape and size conditions and then used to reconstruct the entire dataset, we observed highly similar synergies and patterns of modulation. The synergies were well conserved between monkeys, with two of the synergies exceeding chance structural similarity, and the third being recruited, in both animals, in proportion to the size of the object handled.

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Timing of Muscle Activation in a Hand Movement Sequence

Cited by 69 publications

References 38 publications

Synergy temporal sequences and topography in the spinal cord: evidence for a traveling wave in frog locomotion

Synergy temporal sequences and topography in the spinal cord: evidence for a traveling wave in frog locomotion

Neuromechanics of muscle synergies for posture and movement

Modulation of Muscle Synergy Recruitment in Primate Grasping

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