Phase dependent reflex reversal during walking in chronic spinal cats

Forssberg, Hans; Grillner, Sten; Rossignol, Serge

doi:10.1016/0006-8993(75)91013-6

Cited by 586 publications

(160 citation statements)

References 8 publications

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“…However, lower extremity intralimb coordination has contributions from both spinal and supraspinal mechanisms (Forssberg et al 1975;Forssberg et al 1980;Hiebert et al 1994). Given the cortical contribution to the latency delays, we postulate that disrupted supraspinal centres are mainly responsible for the longer intralimb coupling duration.…”

Section: Disrupted Timing Of Postural Reflexes Contributes To Fallsmentioning

confidence: 83%

Altered timing of postural reflexes contributes to falling in persons with chronic stroke

Marigold

Eng

2006

Exp Brain Res

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The purpose of this study was to determine differences in the timing of postural reflexes and changes in kinematics between those who fell (Fallers) in response to standing platform translations and those who did not (Non-fallers). Forty-four persons with stroke were exposed to unexpected forward and backward platform translations while standing. Surface electromyography from bilateral tibialis anterior, gastrocnemius, rectus femoris, and biceps femoris were recorded along with kinematic data. Those that fell in response to the translations were compared to those who did not fall in terms of (1) postural reflex onset latency, (2) the time interval between the activation of distal and proximal muscles (i.e. intralimb coupling), and (3) changes in joint angles and trunk motion. Approximately 85% of falls occurred in response to the forward translations. Postural reflex onset latencies were delayed and intralimb coupling durations were longer in the Faller versus Non-faller group. At the time that the platform completed the translating motion (300 ms), the Faller group demonstrated higher trunk velocity, greater change in paretic ankle angle, and the trunk was further behind the ankle compared to the Non-faller group. This study suggests that following platform translations, delays in the timing of postural reflexes and disturbed intralimb coupling result in changes in kinematics, which contribute to falls in persons with stroke.

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Section: Disrupted Timing Of Postural Reflexes Contributes To Fallsmentioning

confidence: 83%

Altered timing of postural reflexes contributes to falling in persons with chronic stroke

Marigold

Eng

2006

Exp Brain Res

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“…In cats and lower vertebrates, spinal CPGs are sufficient to produce the basic quadruped locomotor pattern (Grillner and Zangger, 1979;Rossignol et al, 1999) and, by definition, control movement without supraspinal influences or afferent feedback. When sensory information is available, spinal structures alone also provide some degree of flexibility to the basic locomotor pattern (Forssberg et al, 1975, Pearson, 1995. For example, position and load information from the ankle and especially the hip joint strongly influences the timing of the stance-to-swing transition (Grillner and Rossignol, 1978;Duysens and Pearson, 1980).…”

Section: Reactive Feedback Adaptations Do Not Require Cerebellar Controlmentioning

confidence: 99%

Cerebellar Contributions to Locomotor Adaptations during Splitbelt Treadmill Walking

Morton¹,

Bastian²

2006

J. Neurosci.

543

548

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Locomotor adaptability ranges from the simple and fast-acting to the complex and long-lasting and is a requirement for successful mobility in an unpredictable environment. Several neural structures, including the spinal cord, brainstem, cerebellum, and motor cortex, have been implicated in the control of various types of locomotor adaptation. However, it is not known which structures control which types of adaptation and the specific mechanisms by which the appropriate adjustments are made. Here, we used a splitbelt treadmill to test cerebellar contributions to two different forms of locomotor adaptation in humans. We found that cerebellar damage does not impair the ability to make reactive feedback-driven motor adaptations, but significantly disrupts predictive feedforward motor adaptations during splitbelt treadmill locomotion. Our results speak to two important aspects of locomotor control. First, we have demonstrated that different levels of locomotor adaptability are clearly dissociable. Second, the cerebellum seems to play an essential role in predictive but not reactive locomotor adjustments. We postulate that reactive adjustments may instead be predominantly controlled by lower neural centers, such as the spinal cord or brainstem.

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“…Transmission through cutaneous reflexes is modulated in a phase-dependent manner during the locomotor step cycle in intact cats (Forssberg et al, 1975;Drew and Rossignol, 1987) as well as during fictive stepping in immobilized, decerebrate semichronic (LaBella et al, 1992) and chronic (Forssberg et al, 1975(Forssberg et al, , 1977Andersson et al, 1978) spinal cats. Overall, we found that, when significantly modulated during the fictive step cycle, SPEPSPs and CCS-EPSPs (R1) were of maximal amplitude during flexion in a majority of cases both in flexors/bifunctional (5 of 6) and in extensors (20 of 23), whereas MPL-EPSPs (R1) were of maximal amplitude in extension both in flexors/bifunctional (9 of 9) and in extensors (2 of 4).…”

Section: Effect Of Training During Fictive Locomotor Episodesmentioning

confidence: 99%

Step Training-Dependent Plasticity in Spinal Cutaneous Pathways

Côté¹,

Gossard²

2004

J. Neurosci.

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Plasticity after spinal cord injury can be initiated by specific patterns of sensory feedback, leading to a reorganization of spinal networks. For example, proprioceptive feedback from limb loading during the stance phase is crucial for the recovery of stepping in spinal-injured animals and humans. Our recent results showed that step training modified transmission from group I afferents of extensors in spinal cats. However, cutaneous afferents are also activated during locomotion and are necessary for proper foot placement in spinal cats. We therefore hypothesized that step training would also modify transmission in cutaneous pathways to facilitate recovery of stepping. We tested transmission in cutaneous pathways by comparing intracellular responses in lumbar motoneurons (n ϭ 136) in trained (n ϭ 11) and untrained (n ϭ 7) cats spinalized 3-5 weeks before the acute electrophysiological experiment. Three cutaneous nerves were stimulated, and each evoked up to three motoneuronal responses mediated by at least three different pathways. Overall, of 71 cutaneous pathways tested, 10 were modified by step training: transmission was reduced in 7 and facilitated in 3. Remarkably, 6 of 10 involved the medial plantar nerve innervating the plantar surface of the foot, including two of the facilitated pathways. Because the cutaneous reflexes are exaggerated after spinalization, we interpret the decrease in most pathways as a normalization of cutaneous transmission necessary to recover locomotor movements. Overall, the results showed a high degree of specificity in plasticity among cutaneous pathways and indicate that transmission of skin inputs signaling ground contact, in particular, is modified by step training.

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Phase dependent reflex reversal during walking in chronic spinal cats

Cited by 586 publications

References 8 publications

Altered timing of postural reflexes contributes to falling in persons with chronic stroke

Altered timing of postural reflexes contributes to falling in persons with chronic stroke

Cerebellar Contributions to Locomotor Adaptations during Splitbelt Treadmill Walking

Step Training-Dependent Plasticity in Spinal Cutaneous Pathways

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