Changes in intra‐ and interlimb reflexes from hindlimb cutaneous afferents after staggered thoracic lateral hemisections during locomotion in cats

The Journal of Physiology, Год журнала: 2024, Номер 602(9), С. 1987 - 2017

Опубликована: Апрель 9, 2024

Abstract When the foot dorsum contacts an obstacle during locomotion, cutaneous afferents signal central circuits to coordinate muscle activity in four limbs. Spinal cord injury disrupts these interactions, impairing balance and interlimb coordination. We evoked reflexes by electrically stimulating left right superficial peroneal nerves before after two thoracic lateral hemisections placed on opposite sides of at 9‐ 13‐week interval seven adult cats (4 males 3 females). recorded reflex responses ten hindlimb five forelimb muscles bilaterally. After first (right T5–T6) second (left T10–T11) hemisections, coordination fore‐ hindlimbs was altered and/or became less consistent. hemisection, required assistance perform quadrupedal locomotion. Short‐latency homonymous crossed largely remained unaffected staggered hemisections. However, mid‐ long‐latency both occurred frequently In muscles, homolateral diagonal response occurrence significantly decreased all limbs, however, when present, short‐, maintained their phase‐dependent modulation. also observed reduced durations short‐latency inhibitory extensors early hemisection delayed ipsilesional hemisection. Therefore, changes correlated with impaired balance/stability locomotion spinal injury. Restoring transmission could be used as a biomarker facilitate locomotor recovery. image Key points Cutaneous afferent inputs limbs obstacle. Thoracic communication between centres located cervical lumbar levels, limb investigated nerve bilaterally, cats. showed loss/reduction which balance. Targeting pathways projecting help develop therapeutic approaches aimed restoring ascending descending pathways.

Язык: Английский

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Forelimb movements contribute to hindlimb cutaneous reflexes during locomotion in cats

Journal of Neurophysiology, Год журнала: 2024, Номер 131(6), С. 997 - 1013

Опубликована: Май 1, 2024

During quadrupedal locomotion, interactions between spinal and supraspinal circuits somatosensory feedback coordinate forelimb hindlimb movements. How this is achieved not clear. To determine whether movements modulate cutaneous reflexes involved in responding to an external perturbation, we stimulated the superficial peroneal nerve six intact cats during locomotion hindlimb-only (with forelimbs standing on stationary platform) two with a low transection (T12-T13) locomotion. We compared evoked ipsilateral four contralateral muscles. Results showed similar occurrence phase-dependent modulation of short-latency inhibitory excitatory responses cats. However, depth was reduced semitendinosus Additionally, longer-latency occurred less frequently extensor muscles bilaterally whereas more sartorius anterior, respectively. After transection, were both conditions, mid- or abolished. Our results comparison spinal-transected suggest that absence suppresses inputs from structures and/or cervical cord normally contribute reflex

Язык: Английский

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Changes in intra‐ and interlimb reflexes from forelimb cutaneous afferents after staggered thoracic lateral hemisections during locomotion in cats

The Journal of Physiology, Год журнала: 2024, Номер 602(22), С. 6225 - 6258

Опубликована: Сен. 27, 2024

Abstract In quadrupeds, such as cats, cutaneous afferents from the forepaw dorsum signal external perturbations and send inputs to spinal circuits co‐ordinate activity in muscles of all four limbs. How these reflex pathways forelimb are reorganized after an incomplete cord injury is not clear. Using a staggered thoracic lateral hemisections paradigm, we investigated changes intralimb interlimb by electrically stimulating left right superficial radial nerves seven adult cats recording responses five ten hindlimb muscles. After first (right T5–T6) second (left T10–T11) hemisections, forelimb–hindlimb co‐ordination was altered weakened. hemisection, required balance assistance perform quadrupedal locomotion. Short‐, mid‐ long‐latency homonymous crossed their phase modulation remained largely unaffected hemisections. The occurrence homolateral diagonal evoked with nerve stimulation significantly reduced at time point but partially recovered stimulation. These were lost or hemisection. When present, responses, including diagonal, maintained phase‐dependent modulation. Therefore, our results show considerable loss transmission cervical lumbar levels injury, albeit preservation modulation, probably affecting functional perturbations. image Key points Cutaneous afferent muscle limbs during locomotion when contacts obstacle. Thoracic disrupts communication between locomotor centres located levels, impairing limb co‐ordination. We reflexes bilaterally, before cats. showed loss/reduction early hemisection that stimulation, being Targeting projecting could help develop therapeutic approaches aimed restoring ascending descending pathways.

Язык: Английский

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Operation of spinal sensorimotor circuits controlling phase durations during tied-belt and split-belt locomotion after a lateral thoracic hemisection

Опубликована: Янв. 14, 2025

Locomotion is controlled by spinal circuits that interact with supraspinal drives and sensory feedback from the limbs. These sensorimotor interactions are disrupted following cord injury. The thoracic lateral hemisection represents an experimental model of incomplete injury, where connections between brain abolished on one side cord. To investigate effects such injury operation locomotor network, we used our computational cat locomotion recently published in eLife (Rybak et al., 2024) to predict changes cycle phase durations a during treadmill tied-belt (equal left-right speeds) split-belt (unequal conditions. In simulations, “hemisection” was always applied right side. Based model, hypothesized hemisection, contralesional (“intact”, left) network mostly drives, whereas ipsilesional (“hemisected”, right) somatosensory feedback. We then compared simulated results those obtained experiments adult cats before after mid-thoracic same Our confirmed many predicted simulations. show having hindlimb step slow belt, but not fast substantially reduces hemisection. provides explanations for temporal characteristics based altered circuits,

Язык: Английский

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Operation of spinal sensorimotor circuits controlling phase durations during tied-belt and split-belt locomotion after a lateral thoracic hemisection

eLife, Год журнала: 2025, Номер 13

Опубликована: Янв. 27, 2025

Locomotion is controlled by spinal circuits that interact with supraspinal drives and sensory feedback from the limbs. These sensorimotor interactions are disrupted following cord injury. The thoracic lateral hemisection represents an experimental model of incomplete injury, where connections between brain abolished on one side cord. To investigate effects such injury operation locomotor network, we used our computational cat locomotion recently published in eLife (Rybak et al., 2024) to predict changes cycle phase durations a during treadmill tied-belt (equal left-right speeds) split-belt (unequal conditions. In simulations, ‘hemisection’ was always applied right side. Based model, hypothesized contralesional (‘intact’, left) network mostly drives, whereas ipsilesional (‘hemisected’, right) somatosensory feedback. We then compared simulated results those obtained experiments adult cats before after mid-thoracic same Our confirmed many predicted simulations. show having hindlimb step slow belt, but not fast substantially reduces hemisection. provides explanations for temporal characteristics based altered circuits,

Язык: Английский

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Effects of spinal transection and locomotor speed on muscle synergies of the cat hindlimb

The Journal of Physiology, Год журнала: 2025, Номер unknown

Опубликована: Май 5, 2025

Abstract It has been suggested that during locomotion, the nervous system controls movement by activating groups of muscles, or muscle synergies. Analysis synergies can reveal organization spinal locomotor networks and how it depends on state system, such as before after cord injury, different conditions, including a change in speed. The goal this study was to investigate effects transection speed hindlimb their time‐dependent activity patterns adult cats. EMG activities 15 muscles were recorded nine cats either sex tied‐belt treadmill locomotion at speeds 0.4, 0.7 1.0 m/s recovery from low thoracic transection. We determined burst using cluster analysis onset offset times non‐negative matrix factorization (NNMF). found five major each six experimental conditions (2 states × 3 speeds). In case, accounted for least 90% variance. Both modified subgroups composition activation selected However, these changes did not modify general Based obtained results, we propose an pattern formation network two‐level central generator be tested neuromechanical simulations circuits controlling cat locomotion. image Key points networks. locomoting level. all x speeds) include two flexor operating swing phase three extensor stance phase. Major features (the number, patterns) substantially affected speed, suggesting control mechanism operates proposed muscles.

Язык: Английский

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Dynamic spinal reflex adaptation during locomotor adaptation

Journal of Neurophysiology, Год журнала: 2023, Номер 130(4), С. 1008 - 1014

Опубликована: Сен. 13, 2023

The dynamics and interaction of spinal supraspinal centers during locomotor adaptation remain vaguely understood. In this work, we use Hoffmann reflex measurements to investigate changes in gains split-belt adaptation. We show that are dynamically modulated During first exposure transitions, modulation occurs mostly on the leg ipsilateral speed change constitutes rapid suppression or facilitation gains, followed by slow recovery baseline. Over repeated exposure, pattern washes out. further gain strongly correlates with correction asymmetry, cannot be explained solely. argue is likely origins an integral part neural substrate underlying

Язык: Английский

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Forelimb movements contribute to hindlimb cutaneous reflexes during locomotion in cats

bioRxiv (Cold Spring Harbor Laboratory), Год журнала: 2024, Номер unknown

Опубликована: Март 14, 2024

ABSTRACT During quadrupedal locomotion, central circuits interacting with somatosensory feedback coordinate forelimb and hindlimb movements. How this is achieved not clear. To determine if movements modulate cutaneous reflexes involved in responding to an external perturbation, we stimulated the superficial peroneal nerve six intact cats during locomotion hindlimb-only (with forelimbs standing on stationary platform) two spinal-transected locomotion. We compared evoked ipsilateral four contralateral muscles. Results showed similar occurrence phase-dependent modulation of short-latency inhibitory excitatory responses cats. However, depth was reduced semitendinosus Additionally, longer-latency occurred less frequently extensor muscles bilaterally while more sartorius anterior, respectively. After spinal transection, were both conditions, mid- or longer-excitatory abolished. Our results suggest that absence suppresses inputs from supraspinal structures and/or cervical cord normally contribute reflex NEW & NOTEWORTHY coordination involves feedback. demonstrate how movement affects as well show influences reflexes, particularly long-latency responses.

Язык: Английский

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Changes in intra- and interlimb reflexes from forelimb cutaneous afferents after staggered thoracic lateral hemisections during locomotion in cats

bioRxiv (Cold Spring Harbor Laboratory), Год журнала: 2024, Номер unknown

Опубликована: Апрель 23, 2024

In quadrupeds, such as cats, cutaneous afferents from the forepaw dorsum signal external perturbations and send signals to spinal circuits coordinate activity in muscles of all four limbs. How these reflex pathways forelimb are reorganized after an incomplete cord injury is not clear. Using a staggered thoracic lateral hemisections paradigm, we investigated changes intralimb interlimb by electrically stimulating left right superficial radial nerves seven adult cats recording responses five ten hindlimb muscles. After first (right T5-T6) second (left T10-T11) hemisections, forelimb-hindlimb coordination was altered weakened. hemisection, required balance assistance perform quadrupedal locomotion. Short-, mid- long-latency homonymous crossed their phase modulation remained largely unaffected hemisections. The occurrence homolateral diagonal evoked with nerve stimulation significantly reduced at time point but partially recovered stimulation. These were lost or hemisection. When present, responses, including diagonal, maintained phase-dependent modulation. Therefore, our results show considerable loss transmission cervical lumbar levels injury, albeit preservation modulation, likely affecting functional perturbations.

Язык: Английский

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Stepping up after spinal cord injury: negotiating an obstacle during walking

Neural Regeneration Research, Год журнала: 2024, Номер 20(7), С. 1919 - 1929

Опубликована: Авг. 30, 2024

Every day walking consists of frequent voluntary modifications in the gait pattern to negotiate obstacles. After spinal cord injury, stepping over an obstacle becomes challenging. Stepping requires sensorimotor transformations several structures brain, including parietal cortex, premotor and motor cortex. Sensory information planning are transformed into commands, which sent from cortex neuronal circuits alter limb trajectory, coordinate limbs, maintain balance. bidirectional communication between brain is disrupted animals, humans, fail voluntarily modify trajectory step obstacle. Therefore, this review, we discuss neuromechanical control obstacle, why it fails after how recovers a certain extent.

Язык: Английский

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