Function of Segmental Reflexes in the Control of Stepping in Cockroaches and Cats

Pearson, K. G.; Duysens, Jaak

doi:10.1007/978-1-4757-0964-3_21

Cited by 121 publications

(88 citation statements)

References 14 publications

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“…2,4,5,20 : initiation and main tenance of stepping in the paralysed limb was usually possible only when the knee joint was fully extended during stance, the hip joint was extended to more than 1800 after mid stance and the limb became deloaded after previously bearing the full body weight. The patient who had trained independently over several years has deve loped the same strategies for locomotion.…”

Section: Discussionmentioning

confidence: 99%

Laufband locomotion with body weight support improved walking in persons with severe spinal cord injuries

1992

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After low transection of the spinal cord mammalian quadrupeds can be trained to walk on a driven surface indicating that coordinating neuronal circuits persist in the spinal cord segments caudal to the lesion. We trained 8 persons with incomplete spinal cord lesion on a Laufband (driven treadmill) for 1! to 7 months (5 days a week, 30-60 minutes daily) starting 5 to 20 months after injury and found significant improvement in the utilisation of the paralysed limbs during locomotion. Locomotion is described in one additional patient who had trained independently on parallel bars for several years.Five patients had complete functional paralysis in one lower limb when tested in a resting position. In EMG recordings voluntary activity (ie activity induced upon command) was absent or residual in the main flexor and extensor muscles of this limb. In contrast, during locomotion flexion and extension movements were performed and phasic EMG activity was present. In these 5 patients, and in all others reported here, skin sensibility and proprioception are preserved to different degrees in all limbs. In the course of locomotive training of 4 severely paralysed patients the initially habituating flexion reflexes could be entrained in the paralysed limbs as was the case for knee extension during stance. Sub sequently, initial body weight support (BWS) of 40% could be reduced to 0%. The distance covered on the Laufband (0-104 m in the first week) increased significantly (200-410 m) in the last week of training as did speed (0-10 to 14-23 m/min). More importantly, this training subsequently allowed patients to walk on a static surface for 100 to 200 meters while voluntary activity remained absent in the paralysed limb when tested at rest.Similar progress was achieved in the 4 less severely paralysed patients. The one patient who had trained independently on parallel bars for several years is described walking on a static surface for 40 meters with the help of a walker, though he had one completely and one near completely paralysed lower limb.It appears that bipedal stepping with consequent knee extension and stabilisa tion can be taught after unilateral complete or near complete loss of voluntary activity, suggesting the manifestation of complex reflex motor patterns at the spinal level.

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Section: Discussionmentioning

confidence: 99%

Laufband locomotion with body weight support improved walking in persons with severe spinal cord injuries

1992

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“…However, there is strong experimental evidence supporting the asymmetrical model (Pearson and Duysens, 1976). Asymmetrical models in different species are based on the assumption that neurons with endogenous oscillatory capabilities activate exclusively flexor motoneurons, and that rhythmic activity in flexor motoneurons can be produced in the absence of extensor activity, but not the opposite.…”

Section: Justification Of Use Of the Asymmetrical Model Of The Cpg Almentioning

confidence: 99%

An Intersegmental Neuronal Architecture for Spinal Wave Propagation under Deletions

Pérez¹,

Tapia²,

Mirasso³

et al. 2009

J. Neurosci.

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Recent studies have established and characterized the propagation of traveling electrical waves along the cat spinal cord during scratching, but the neuronal architecture that allows for the persistence of such waves even during periods of absence of bursts of motoneuron activity (deletions) is still unclear. Here we address this problem both theoretically and experimentally. Specifically, we monitored during long lasting periods of time the global electrical activity of spinal neurons during scratching. We found clear deletions of unaltered cycle in extensor activity without associated deletions of the traveling spinal wave. Furthermore, we also found deletions with a perturbed cycle associated with a concomitant absence of the traveling spinal wave. Numerical simulations of an asymmetric two-layer model of a central-pattern generator distributed longitudinally along the spinal cord qualitatively reproduce the sinusoidal traveling waves, and are able to replicate both classes of deletions. We believe these findings shed light into the longitudinal organization of the central-pattern generator networks in the spinal cord.

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“…Another important effect of ankle load afferents on locomotion is that a rapid decrease in afferent firing during unloading appears to trigger the swing phase of gait (Grillner and Rossignol 1978;Pearson and Duysens 1976;Pearson et al 1992). In the current study, load release provided a strong cue for triggering a reflex response; however, the ensuing response did not strongly resemble swing.…”

Section: Possible Role Of Locomotor Networkmentioning

confidence: 99%

“…Load afferents from ankle plantar flexors and the skin of the foot have been proven to be important modulators of spinal locomotion in the cat (Conway et al 1987;Pearson 1976, 1980;Guertin et al 1995;Pearson and Collins 1993;Pearson and Duysens 1976;Pearson et al 1992;Whelan et al 1995). For example, in spinalized cats walking on a treadmill, the swing phase will not initiate if the contralateral limb is not in position to bear load (Grillner and Rossignol 1978).…”

Section: Introductionmentioning

confidence: 99%

Spastic Reflexes Triggered by Ankle Load Release in Human Spinal Cord Injury

Schmit

2006

Journal of Neurophysiology

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Function of Segmental Reflexes in the Control of Stepping in Cockroaches and Cats

Cited by 121 publications

References 14 publications

Laufband locomotion with body weight support improved walking in persons with severe spinal cord injuries

Laufband locomotion with body weight support improved walking in persons with severe spinal cord injuries

An Intersegmental Neuronal Architecture for Spinal Wave Propagation under Deletions

Spastic Reflexes Triggered by Ankle Load Release in Human Spinal Cord Injury

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