The locomotion of the low spinal cat I. Coordination within a hindlimb

Forssberg, Hans; Grillner, Sten; Halbertsma, J.

doi:10.1111/j.1748-1716.1980.tb06533.x

Cited by 254 publications

(104 citation statements)

References 38 publications

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“…The present results clearly demonstrate that phasedependent gating of motor-evoked responses can be mediated by the spinal locomotor circuitry. These data are remarkably similar to the phase-dependent cutaneous reflex reversal observed when spinal cats are tripped (Forssberg et al, 1980).…”

Section: Phase-dependent Modulation Of Motor-evoked Potentialssupporting

confidence: 76%

Epidural Stimulation Induced Modulation of Spinal Locomotor Networks in Adult Spinal Rats

Lavrov

Fong

et al. 2008

Journal of Neuroscience

140

122

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The importance of the in vivo dynamic nature of the circuitries within the spinal cord that generate locomotion is becoming increasingly evident. We examined the characteristics of hindlimb EMG activity evoked in response to epidural stimulation at the S1 spinal cord segment in complete midthoracic spinal cord-transected rats at different stages of postlesion recovery. A progressive and phasedependent modulation of monosynaptic (middle) and long-latency (late) stimulation-evoked EMG responses was observed throughout the step cycle. During the first 3 weeks after injury, the amplitude of the middle response was potentiated during the EMG bursts, whereas after 4 weeks, both the middle and late responses were phase-dependently modulated. The middle-and late-response magnitudes were closely linked to the amplitude and duration of the EMG bursts during locomotion facilitated by epidural stimulation. The optimum stimulation frequency that maintained consistent activity of the long-latency responses ranged from 40 to 60 Hz, whereas the shortlatency responses were consistent from 5 to 130 Hz. These data demonstrate that both middle and late evoked potentials within a motor pool are strictly gated during in vivo bipedal stepping as a function of the general excitability of the motor pool and, thus, as a function of the phase of the step cycle. These data demonstrate that spinal cord epidural stimulation can facilitate locomotion in a time-dependent manner after lesion. The long-latency responses to epidural stimulation are correlated with the recovery of weight-bearing bipedal locomotion and may reflect activation of interneuronal central pattern-generating circuits.

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Section: Phase-dependent Modulation Of Motor-evoked Potentialssupporting

confidence: 76%

Epidural Stimulation Induced Modulation of Spinal Locomotor Networks in Adult Spinal Rats

Lavrov

Fong

et al. 2008

Journal of Neuroscience

140

122

View full text Add to dashboard Cite

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“…36 The main objective of the present study was to measure how SCI subjects adapt to changes in the walking speed. Studies of hindlimb locomotion in spinalized cats [37][38][39] have shown that adaptation to increasing treadmill speed was possible, but that this adaptation was limited to a maximal speed varying between 0.8 and 1.0 m/s. In the spinal cat, the limited adaptation to increases in speed is presumably because of the absence of descending tracts and achieved with input solely from peripheral influence.…”

Section: Discussionmentioning

confidence: 99%

Treadmill walking in incomplete spinal-cord-injured subjects: 1. Adaptation to changes in speed

2003

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Walking in spinal-cord-injured (SCI) subjects is usually achieved at a lower speed than in normal subjects. Study design/methods: Time and distance parameters, angular displacements of lower limbs and electromyographic (EMG) activity were measured for seven normal and seven SCI subjects at several walking speeds. Analyses of variance were used for comparing groups and speeds. Objectives: First, to measure the adaptability of SCI subjects' walking pattern to different speeds (0.1-1.0 m/s), and to compare it to that of normal subjects. Second, to characterize SCI subjects' walking pattern as compared to that of normal subjects at a matched treadmill speed (0.3 m/s). Setting: University-Based Human Gait Laboratory, Montreal, Canada. Results: SCI subjects' pattern adapted to a limited range of speeds. Longer cycle duration, flexed knee at foot contact, increased hip joint flexion at foot contact and during swing, and altered coordination of hip and knee joints were found for the SCI group. At all speeds, duration of muscle activity was longer in the SCI group and the increase in amplitude of soleus EMG activity at higher speeds was not specific to push-off. The importance of matching the walking speed of SCI and normal subjects in order to differentiate the features that are a consequence of SCI subjects' reduced walking speed rather than a direct consequence of the injury is demonstrated. Conclusions: All SCI subjects could adapt to a narrow range of speeds and only three could reach the maximal tested speed. This limited maximal speed seems to be a consequence of SCI subjects having reached their limit in increasing stride length and not being able to increase stride frequency further. This limitation in increasing stride frequency is likely because of the altered neural drive. Sponsorship: Neuroscience Network of the Canadian Centre of Excellence.

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“…The breakthrough of rehabilitative training following SCI is based on studies in cats, showing that following complete transection a locomotor pattern could be initiated in the paralyzed hindlimbs [36,37]. Although no connection to the brain existed, this locomotor "recovery" could be amplified with treadmill training, ultimately resulting in weight-supported stepping on a treadmill [38,39].…”

Section: Activity-based Approachesmentioning

confidence: 99%

Plasticity After Spinal Cord Injury: Relevance to Recovery and Approaches to Facilitate It

2011

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Summary: Motor, sensory, and autonomic functions can spontaneously return or recover to varying extents in both humans and animals, regardless of the traumatic spinal cord injury (SCI) level and whether it was complete or incomplete. In parallel, adverse and painful functions can appear. The underlying mechanisms for all of these diverse functional changes are summarized under the term plasticity. Our review will describe what is known regarding this phenomenon after traumatic SCI and focus on its relevance to motor and sensory recovery. Although it is still somewhat speculative, plasticity can be found throughout the neuraxis and includes various changes ranging from alterations in the properties of spared neuronal circuitries, intact or lesioned axon collateral sprouting, and synaptic rearrangements. Furthermore, we will discuss a selection of potential approaches for facilitating plasticity as possible SCI treatments. Because a mechanism underlying spontaneous plasticity and recovery might be motor activity and the related neuronal activity, activity-based therapies are being used and investigated both clinically and experimentally. Additional pharmacological and gene-delivery approaches, based on plasticity being dependent on the delicate balance between growth inhibition and promotion as well as the basic intrinsic growth ability of the neurons themselves, have been found to be effective alone and in combination with activitybased therapies. The positive results have to be tempered with the reality that not all plasticity is beneficial. Therefore, a tremendous number of questions still need to be addressed. Ultimately, answers to these questions will enhance plasticity's potential for improving the quality of life for persons with SCI.

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The locomotion of the low spinal cat I. Coordination within a hindlimb

Cited by 254 publications

References 38 publications

Epidural Stimulation Induced Modulation of Spinal Locomotor Networks in Adult Spinal Rats

Epidural Stimulation Induced Modulation of Spinal Locomotor Networks in Adult Spinal Rats

Treadmill walking in incomplete spinal-cord-injured subjects: 1. Adaptation to changes in speed

Plasticity After Spinal Cord Injury: Relevance to Recovery and Approaches to Facilitate It

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