101
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Cheung VCK, d'Avella A, Tresch MC, Bizzi E. Central and sensory contributions to the activation and organization of muscle synergies during natural motor behaviors. J Neurosci 2006; 25:6419-34. [PMID: 16000633 PMCID: PMC6725265 DOI: 10.1523/jneurosci.4904-04.2005] [Citation(s) in RCA: 320] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Previous studies have suggested that the motor system may simplify control by combining a small number of muscle synergies represented as activation profiles across a set of muscles. The role of sensory feedback in the activation and organization of synergies has remained an open question. Here, we assess to what extent the motor system relies on centrally organized synergies activated by spinal and/or supraspinal commands to generate motor outputs by analyzing electromyographic (EMG) signals collected from 13 hindlimb muscles of the bullfrog during swimming and jumping, before and after deafferentation. We first established that, for both behaviors, the intact and deafferented data sets possess low and similar dimensionalities. Subsequently, we used a novel reformulation of the non-negative matrix factorization algorithm to simultaneously search for synergies shared by, and synergies specific to, the intact and deafferented data sets. Most muscle synergies were identified as shared synergies, suggesting that EMGs of locomotor behaviors are generated primarily by centrally organized synergies. Both the amplitude and temporal patterns of the activation coefficients of most shared synergies, however, were altered by deafferentation, suggesting that sensory inflow modulates activation of those centrally organized synergies. For most synergies, effects of deafferentation on the activation coefficients were not consistent across frogs, indicating substantial interanimal variability of feedback actions. We speculate that sensory feedback might adapt recruitment of muscle synergies to behavioral constraints, and the few synergies specific to the intact or deafferented states might represent afferent-specific modules or feedback reorganization of spinal neuronal networks.
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Affiliation(s)
- Vincent C K Cheung
- Division of Health Sciences and Technology, Harvard Medical School, Cambridge, Massachusetts 02139, USA
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102
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Abstract
In awake cats sitting with the head restrained, scratching was evoked using stimulation of the ear. Cats scratched the shoulder area, consistently failing to reach the ear. Kinematics of the hind limb movements and the activity of ankle muscles, however, were similar to those reported earlier in unrestrained cats. The activity of single neurons in the hind limb representation of the motor cortex, including pyramidal tract neurons (PTNs), was examined. During the protraction stage of the scratch response, the activity in 35% of the neurons increased and in 50% decreased compared with rest. During the rhythmic stage, the motor cortex population activity was approximately two times higher compared with rest, because the activity of 53% of neurons increased and that of 33% decreased in this stage. The activity of 61% of neurons was modulated in the scratching rhythm. The average depth of frequency modulation was 12.1 ± 5.3%, similar to that reported earlier for locomotion. The phases of activity of different neurons were approximately evenly distributed over the scratch cycle. There was no simple correlation between resting receptive field properties and the activity of neurons during the scratch response. We conclude that the motor cortex participates in both the protraction and the rhythmic stages of the scratch response.
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Affiliation(s)
- Mikhail G Sirota
- Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, AZ 85013, USA
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103
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Liebermann DG, Buchman AS, Franks IM. Enhancement of motor rehabilitation through the use of information technologies. Clin Biomech (Bristol, Avon) 2006; 21:8-20. [PMID: 16198463 DOI: 10.1016/j.clinbiomech.2005.08.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Accepted: 08/10/2005] [Indexed: 02/07/2023]
Abstract
The recent development of information technologies has dramatically increased the tools available for facilitating motor rehabilitation. This review focuses on technologies which can be used to augment movement-related information both to patients as well as to their therapists. A brief outline of the motor system emphasizes the role of spinal motor neurons in the control of voluntary movement and rehabilitative efforts. Technologies which induce passive motion to stimulate spinal motor output as well as technologies that stimulate active voluntary movements are discussed. Finally, we review technologies and notational methods that can be used to quantify and assess the quality of movement for evaluating the efficacy of motor rehabilitation efforts. We conclude that stronger evidence is necessary to determine the applicability of the wide range of technologies now available to clinical rehabilitation efforts.
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Affiliation(s)
- Dario G Liebermann
- Department of Physical Therapy, Sackler Faculty of Medicine, University of Tel Aviv, Israel.
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104
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Flash T, Hochner B. Motor primitives in vertebrates and invertebrates. Curr Opin Neurobiol 2005; 15:660-6. [PMID: 16275056 DOI: 10.1016/j.conb.2005.10.011] [Citation(s) in RCA: 203] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2005] [Accepted: 10/21/2005] [Indexed: 10/25/2022]
Abstract
In recent years different lines of evidence have led to the idea that motor actions and movements in both vertebrates and invertebrates are composed of elementary building blocks. The entire motor repertoire can be spanned by applying a well-defined set of operations and transformations to these primitives and by combining them in many different ways according to well-defined syntactic rules. Motor and movement primitives and modules might exist at the neural, dynamic and kinematic levels with complicated mapping among the elementary building blocks subserving these different levels of representation. Hence, while considerable progress has been made in recent years in unravelling the nature of these primitives, new experimental, computational and conceptual approaches are needed to further advance our understanding of motor compositionality.
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Affiliation(s)
- Tamar Flash
- Department of Computer Science and Applied Mathematics, Weizmann Institute of Science, Rehovot 76100, Israel.
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105
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Schaal S, Schweighofer N. Computational motor control in humans and robots. Curr Opin Neurobiol 2005; 15:675-82. [PMID: 16271466 DOI: 10.1016/j.conb.2005.10.009] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2005] [Accepted: 10/21/2005] [Indexed: 11/22/2022]
Abstract
Computational models can provide useful guidance in the design of behavioral and neurophysiological experiments and in the interpretation of complex, high dimensional biological data. Because many problems faced by the primate brain in the control of movement have parallels in robotic motor control, models and algorithms from robotics research provide useful inspiration, baseline performance, and sometimes direct analogs for neuroscience.
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Affiliation(s)
- Stefan Schaal
- Computer Science, Neuroscience & Biokinesiology and Physical Therapy, University of Southern California, 3641 Watt Way, Los Angeles, CA 90089, USA.
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106
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Ivanenko YP, Cappellini G, Dominici N, Poppele RE, Lacquaniti F. Coordination of locomotion with voluntary movements in humans. J Neurosci 2005; 25:7238-53. [PMID: 16079406 PMCID: PMC6725226 DOI: 10.1523/jneurosci.1327-05.2005] [Citation(s) in RCA: 280] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2005] [Revised: 06/16/2005] [Accepted: 06/17/2005] [Indexed: 11/21/2022] Open
Abstract
Muscle activity occurring during human locomotion can be accounted for by five basic temporal activation patterns in a variety of locomotion conditions. Here, we examined how these activation patterns interact with muscle activity required for a voluntary movement. Subjects produced a voluntary movement during locomotion, and we examined the resulting kinematics, kinetics, and EMG activity in 16-31 ipsilateral limb and trunk muscles during the tasks. There were four voluntary tasks added to overground walking (approximately 5 km/h) in which subjects kicked a ball, stepped over an obstacle, or reached down and grasped an object on the floor (weight support on either the right or the left foot). Statistical analyses of EMG waveforms showed that the five basic locomotion patterns were invariantly present in each task, although they could be differently weighted across muscles, suggesting a characteristic locomotion timing of muscle activations. We also observed a separate activation that was timed to the voluntary task. The coordination of locomotion with the voluntary task was accomplished by combining activation timings that were associated separately with the voluntary task and locomotion. Activation associated with the voluntary tasks was either synchronous with the timing for locomotion or had additional activations not represented in the basic locomotion timing. We propose that this superposition of an invariant locomotion timing pattern with a voluntary activation timing may be consistent with the proposal suggesting that compound movements are produced through a superposition of motor programs.
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Affiliation(s)
- Yuri P Ivanenko
- Department of Neuromotor Physiology, Scientific Institute Foundation Santa Lucia, 00179 Rome, Italy.
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107
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Saltiel P, Wyler-Duda K, d'Avella A, Ajemian RJ, Bizzi E. Localization and connectivity in spinal interneuronal networks: the adduction-caudal extension-flexion rhythm in the frog. J Neurophysiol 2005; 94:2120-38. [PMID: 15928065 DOI: 10.1152/jn.00117.2005] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We have previously reported that focal intraspinal N-methyl-d-aspartate (NMDA) iontophoresis in the frog elicits a motor output, which is organized in terms of its constituent isometric force directions at the ipsilateral ankle and its topography. Furthermore, the associated EMG patterns can be reconstructed as the linear combinations of seven muscle synergies, labeled A to G. We now focus on one of the most common NMDA-elicited outputs, the adduction-caudal extension-flexion rhythm, and examine the relationship between the different force phases in terms of synergies and topography. Two distinct EMG patterns produce caudal extensions, and only one of the two patterns is used at most sites. The key synergy combinations for the two patterns are B + e and D + c (strongest synergies capitalized). These two patterns map at distinct locations in the lumbar cord. Within individual sites rhythms, we find linkages among the synergies used to produce adductions, the onsets of flexions after caudal extensions, and the synergy pattern producing the caudal extensions. For example, the synergy composition of adductions at B + e caudal extension sites is dominated by E + b and at D + c caudal extension sites by C + d. The two types of adductions map at distinct locations, situated between the two caudal extension regions. Specifically the linked patterns of caudal extension-adduction interleave rostrocaudally in a CE2-ADD1-ADD2-CE1 sequence, where 1 and 2 refer to the two pattern types. The implications of this topography and connectivity with respect to motor systems organization and behaviors are discussed.
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Affiliation(s)
- Philippe Saltiel
- Department of Brain and Cognitive Sciences, McGovern Institute for Brain Research, Massachusetts Institute of Technology, 77 Massachusetts Ave., E25-526, Cambridge, Massachusetts 02139, USA.
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108
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Mushahwar VK, Aoyagi Y, Stein RB, Prochazka A. Movements generated by intraspinal microstimulation in the intermediate gray matter of the anesthetized, decerebrate, and spinal cat. Can J Physiol Pharmacol 2005; 82:702-14. [PMID: 15523527 DOI: 10.1139/y04-079] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The intermediate laminae of the lumbosacral spinal cord are suggested to contain a small number of specialized neuronal circuits that form the basic elements of movement construction ("movement primitives"). Our aim was to study the properties and state dependence of these hypothesized circuits in comparison with movements elicited by direct nerve or muscle stimulation. Microwires for intraspinal microstimulation (ISMS) were implanted in intermediate laminae throughout the lumbosacral enlargement. Movement vectors evoked by ISMS were compared with those evoked by stimulation through muscle and nerve electrodes in cats that were anesthetized, then decerebrated, and finally spinalized. Similar movements could be evoked under anesthesia by ISMS and nerve and muscle stimulation, and these covered the full work space of the limb. ISMS-evoked movements were associated with the actions of nearby motoneuron pools. However, after decerebration and spinalization, ISMS-evoked movements were dominated by flexion, with few extensor movements. This indicates that the outputs of neuronal networks in the intermediate laminae depend significantly on descending input and on the state of the spinal cord. Frequently, the outputs also depended on stimulus intensity. These experiments suggest that interneuronal circuits in the intermediate and ventral regions of the spinal cord overlap and their function may be to process reflex and descending activity in a flexible manner for the activation of nearby motoneuron pools.
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Affiliation(s)
- V K Mushahwar
- Department of Biomedical Engineering, Centre for Neuroscience, 513 Heritage Medical Research Center, Faculty of Medicine, University of Alberta, Edmonton, Alberta T6G 2S2, Canada.
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109
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Jing J, Cropper EC, Hurwitz I, Weiss KR. The construction of movement with behavior-specific and behavior-independent modules. J Neurosci 2004; 24:6315-25. [PMID: 15254087 PMCID: PMC6729538 DOI: 10.1523/jneurosci.0965-04.2004] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Growing evidence suggests that different forms of complex motor acts are constructed through flexible combinations of a small number of modules in interneuronal networks. It remains to be established, however, whether a module simply controls groups of muscles and functions as a computational unit for use in multiple behaviors (behavior independent) or whether a module controls multiple salient features that define one behavior and is used primarily for that behavior (behavior specific). We used the Aplysia feeding motor network to examine the two proposals by studying the functions of identifiable interneurons. We identified three types of motor programs that resemble three types of behaviors that Aplysia produce: biting, swallowing, and rejection. Two ingestive programs (biting, swallowing) are defined by two movement parameters of the feeding apparatus (the radula): one is the same in both programs (phasing of radula closure motoneurons relative to radula protraction-retraction), whereas the other parameter (protraction duration) is different in the two programs. In each program, these two parameters were specified together by an individual neuron, but the neurons in each were different (B40 for biting, B30 for swallowing). These findings support the existence of behavior-specific modules. Furthermore, neuron B51 was found to mediate a phase that can be flexibly added on to both ingestive and egestive-rejection programs, suggesting that B51 may be a behavior-independent module. The functional interpretation of the role played by these modules is supported by the patterns of synaptic connectivity that they make. Thus, both behavior-specific and behavior-independent modules are used to construct complex behaviors.
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Affiliation(s)
- Jian Jing
- Department of Physiology and Biophysics, Mount Sinai School of Medicine, New York, New York 10029-6574, USA.
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110
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Stein PSG. Neuronal control of turtle hindlimb motor rhythms. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2004; 191:213-29. [PMID: 15452660 DOI: 10.1007/s00359-004-0568-6] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2004] [Revised: 08/03/2004] [Accepted: 08/12/2004] [Indexed: 11/29/2022]
Abstract
The turtle, Trachemys scripta elegans, uses its hindlimb during the rhythmic motor behaviors of walking, swimming, and scratching. For some tasks, one or more motor strategies or forms may be produced, e.g., forward swimming or backpaddling. This review discusses experiments that reveal characteristics of the spinal neuronal networks producing these motor behaviors. Limb-movement studies show shared properties such as rhythmic alternation between hip flexion and hip extension, as well as variable properties such as the timing of knee extension in the cycle of hip movements. Motor-pattern studies show shared properties such as rhythmic alternation between hip flexor and hip extensor motor activities, as well as variable properties such as modifiable timing of knee extensor motor activity in the cycle of hip motor activity. Motor patterns also display variations such as the hip-extensor deletion of rostral scratching. Neuronal-network studies reveal mechanisms responsible for movement and motor-pattern properties. Some interneurons in the spinal cord have shared activities, e.g., each unit is active during more than one behavior, and have distinct characteristics, e.g., each unit is most excited during a specific behavior. Interneuronal recordings during variations support the concept of modular organization of central pattern generators in the spinal cord.
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Affiliation(s)
- P S G Stein
- Department of Biology, Washington University, St. Louis, MO 63130, USA.
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111
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Garcia-Perez E, Zoccolan D, Pinato G, Torre V. Dynamics and Reproducibility of a Moderately Complex Sensory-Motor Response in the Medicinal Leech. J Neurophysiol 2004; 92:1783-95. [PMID: 15115783 DOI: 10.1152/jn.01240.2003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Local bending, a motor response caused by mechanical stimulation of the leech skin, has been shown to be remarkably reproducible, in its initial phase, despite the highly variable firing of motoneurons sustaining it. In this work, the reproducibility of local bending was further analyzed by monitoring it over a longer period of time and by using more intact preparations, in which muscle activation in an entire body segment was studied. Our experiments showed that local bending is a moderately complex motor response, composed of a sequence of four different phases, which were consistently identified in all leeches. During each phase, longitudinal and circular muscles in specific areas of the body segment acted synergistically, being co-activated or co-inhibited depending on their position relative to the stimulation site. Onset and duration of the first phase were reproducible across different trials and different animals as a result of the massive co-activation of excitatory motoneurons sustaining it. The other phases were produced by the inhibition of excitatory and activation of inhibitory motoneurons, and also by the intrinsic relaxation dynamics of leech muscles. As a consequence, their duration and relative timing was variable across different preparations, whereas their order of appearance was conserved. These results suggest that, during local bending, the leech neuromuscular system 1) operates a reduction of its available degrees of freedom, by simultaneously recruiting groups of otherwise antagonistic muscles and large populations of motoneurons; and 2) ensures reliability and effectiveness of this escape reflex, by guaranteeing the reproducibility of its crucial initial phase.
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Affiliation(s)
- Elizabeth Garcia-Perez
- Scuola Internazionale Superiore di Studi Avanzati and Isituto Nazionale di Fisica della Materia, Via Beirut 7, 34014 Trieste, Italy.
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