An Electromyographic Analysis of Muscular Activity in the Hindlimb of the Cat during Unrestrained Locomotion

Engberg, I.; Lundberg, A.

doi:10.1111/j.1748-1716.1969.tb04415.x

Cited by 446 publications

(175 citation statements)

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“…The difference may partly be explained by the different time courses of both types of locomotion. The second peak of activity in the knee flexors was only well developed during a rather fast trot and almost vanished during a slower walk (Engberg & Lundberg, 1969). Moreover, the walk described by these authors in the freely moving cat is much faster (about 0-6 s per step cycle) than the rhythm observed during fictive locomotion (about 3 s per step cycle).…”

Section: Discussionmentioning

confidence: 80%

Phasic modulation of trunk muscle efferents during fictive spinal locomotion in cats.

Koehler¹,

Schomburg²,

Steffens³

1984

The Journal of Physiology

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SUMMARY1. In high spinal paralysed cats electromyograms were recorded from nerves supplying lumbar back muscles (longissimus dorsi) and abdominal muscles (obliquus abdominis externus) during fictive locomotion induced by I.v. injection of nialamide and L-DOPA. Activity in nerves to hind-limb muscles was also recorded.2. During periods of stable 'locomotor' activity in the hind-limb nerves the efferents to the back and abdominal trunk muscles were generally also rhythmically active. Three different patterns of activity were observed.3. The predominant rhythmic pattern showed a synchronous activation of the efferents to the back and abdominal muscles of one side together with an activation of the hind-limb flexors of that side, alternating with activation of the efferents to the corresponding contralateral muscles. This pattern was very stable and could last for about 3 h. Such a pattern of activity would be expected during the alternate stepping characteristic of walking and trotting.4. The second type of rhythmic locomotor activity was characterized by a synchronous bilateral activation ofthe efferents to the back muscles, alternating with activation of the abdominal muscles on both sides. This pattern occurred only for short periods and appears to correspond to the activity during in-phase stepping such as occurs during a gallop.5. Beside these well co-ordinated patterns less well co-ordinated rhythmic activities were also observed. These included regular rhythmic activity which occurred independently in different muscle groups as well as irregular rhythmic activity with unstable phase relations between different muscle groups.6. The rhythmic locomotor activity in efferents to trunk and limb muscles could be modulated by afferent nerve stimulation and by hypoxia.7. The results reveal that the spinal cord deprived of its supraspinal and peripheral control may generate a variety of different locomotor patterns, which incorporate the trunk muscles in an apparently meaningful way.

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Section: Discussionmentioning

confidence: 80%

Phasic modulation of trunk muscle efferents during fictive spinal locomotion in cats.

Koehler¹,

Schomburg²,

Steffens³

1984

The Journal of Physiology

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“…The subject-specific sequence of muscle onsets may result from a variety of factors, including electrode placement variation and/ or small fluctuations in motoneuron pool excitability. Further, although movement/muscle timing can be influenced by phasic (perturbation) stimuli (Gracco and Abbs, 1988a), it appears that the onset of muscle activity is primarily a central phenomenon (see also Engberg and Lundberg, 1969;Grillner and Zangger, 1975, for locomotion). The systematic relations in the time course of all muscle patterns (e.g., onsets and time to peak amplitude) and the resulting kinematic relations are consistent with a temporal scaling of central motor commands to all synergistic muscles (e.g., "common drive"; DeLuca et al, 1982).…”

Section: Discussionmentioning

confidence: 99%

Timing factors in the coordination of speech movements

Gracco

1988

J. Neurosci.

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Speech movement coordination involves substantial timing adjustments among multiple degrees of muscles and movement freedom. The present investigation examined the kinematic and muscle timing adjustments associated with the production of select speech movements. For oral closing movements, the timing of the upper lip, lower lip, and jaw peak velocities were found to be tightly coupled, apparently reflecting a coordinative strategy. In contrast, oral opening movements demonstrated reduced temporal coupling and inconsistent sequencing across subjects. Overall, it appears that the temporal organization of speech movements varies with the specific movement goals. In order to evaluate the coordinative patterns for oral closing in detail, the temporal adjustments of multiple perioral muscles associated with the systematic closing peak velocity relations were examined. The relative timing of muscle onsets and peak EMG amplitudes was found to be predictably related to the peak velocity timing variations, suggesting that the motor commands are temporally scaled to generate changes in speaking conditions. It was also found that the mechanical properties of the speech articulators influence movement coordination and can be exploited to maximize movement efficiency. The systematic change in muscle timing characteristics for all synergistic muscles apparently reduces the degrees of freedom to control, thereby facilitating the coordination process.

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“…During locomotion, however, some motoneuron pools display activity during both the flexion and extension phases of the step cycle and there are differences in the onset and offset of activity in individual flexor and extensor pools (see Rossignol 1996). Originally it was suggested that proprioceptive afferent input was responsible for converting simple alternating flexor and extensor activity into a more complex pattern (Engberg and Lundberg 1969). The persistence of more complex activity patterns following bilateral deafferentation of the hindlimbs in decerebrate cats, however, led Grillner and Zangger (1975) to conclude that the locomotor CPG "… does not simply generate an alternate activation of flexors and extensors but a more delicate pattern that will sequentially start and terminate the activity in the appropriate muscles at the correct instance".…”

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confidence: 99%

Organization of mammalian locomotor rhythm and pattern generation

McCrea

Rybak

2008

Brain Research Reviews

604

506

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Central pattern generators (CPGs) located in the spinal cord produce the coordinated activation of flexor and extensor motoneurons during locomotion. Previously proposed architectures for the spinal locomotor CPG have included the classical half-center oscillator and the unit burst generator (UBG) comprised of multiple coupled oscillators. We have recently proposed another organization in which a two-level CPG has a common rhythm generator (RG) that controls the operation of the pattern formation (PF) circuitry responsible for motoneuron activation. These architectures are discussed in relation to recent data obtained during fictive locomotion in the decerebrate cat. The data show that the CPG can maintain the period and phase of locomotor oscillations both during spontaneous deletions of motoneuron activity and during sensory stimulation affecting motoneuron activity throughout the limb. The proposed two-level CPG organization has been investigated with a computational model which incorporates interactions between the CPG, spinal circuits and afferent inputs. The model includes interacting populations of spinal interneurons and motoneurons modeled in the Hodgkin-Huxley style. Our simulations demonstrate that a relatively simple CPG with separate RG and PF networks can realistically reproduce many experimental phenomena including spontaneous deletions of motoneuron activity and a variety of effects of afferent stimulation. The model suggests plausible explanations for a number of features of real CPG operation that would be difficult to explain in the framework of the classical single-level CPG organization. Some modeling predictions and directions for further studies of locomotor CPG organization are discussed. KeywordsCPG; computational models; spinal cord; decerebrate; cat Half-center organization of the central pattern generatorMore than 90 years ago, T. Graham Brown (1911) demonstrated that the cat spinal cord can generate a locomotor rhythm in the absence of input from higher centers and afferent feedback. These and later investigations led to the widely accepted concept of central pattern generators Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Author ManuscriptBrain Res Rev. Author manuscript; available in PMC 2009 January 1. Published in final edited form as:Brain Res Rev. 2008 January ; 57(1): 134-146. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author Manuscript (CPGs) which reside within the central nervous systems of invertebrates and vertebrates and control various rhythmic movements. Graham Brown (1914) also proposed...

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An Electromyographic Analysis of Muscular Activity in the Hindlimb of the Cat during Unrestrained Locomotion

Cited by 446 publications

References 18 publications

Phasic modulation of trunk muscle efferents during fictive spinal locomotion in cats.

Phasic modulation of trunk muscle efferents during fictive spinal locomotion in cats.

Timing factors in the coordination of speech movements

Organization of mammalian locomotor rhythm and pattern generation

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