scholarly journals Integrating multiple sensory systems to modulate neural networks controlling posture

2015 ◽  
Vol 114 (6) ◽  
pp. 3306-3314 ◽  
Author(s):  
I. Lavrov ◽  
Y. Gerasimenko ◽  
J. Burdick ◽  
H. Zhong ◽  
R. R. Roy ◽  
...  
Keyword(s):  
Neural Networks ◽  
Spinal Cord ◽  
Weight Bearing ◽  
Cumulative Effect ◽  
Epidural Stimulation ◽  
Lumbosacral Spinal Cord ◽  
Hindlimb Muscles ◽  
Neuronal Mechanisms ◽  
Cord Injury ◽  
Complete Spinal Cord Injury

In this study we investigated the ability of sensory input to produce tonic responses in hindlimb muscles to facilitate standing in adult spinal rats and tested two hypotheses: 1) whether the spinal neural networks below a complete spinal cord transection can produce tonic reactions by activating different sensory inputs and 2) whether facilitation of tonic and rhythmic responses via activation of afferents and with spinal cord stimulation could engage similar neuronal mechanisms. We used a dynamically controlled platform to generate vibration during weight bearing, epidural stimulation (at spinal cord level S1), and/or tail pinching to determine the postural control responses that can be generated by the lumbosacral spinal cord. We observed that a combination of platform displacement, epidural stimulation, and tail pinching produces a cumulative effect that progressively enhances tonic responses in the hindlimbs. Tonic responses produced by epidural stimulation alone during standing were represented mainly by monosynaptic responses, whereas the combination of epidural stimulation and tail pinching during standing or epidural stimulation during stepping on a treadmill facilitated bilaterally both monosynaptic and polysynaptic responses. The results demonstrate that tonic muscle activity after complete spinal cord injury can be facilitated by activation of specific combinations of afferent inputs associated with load-bearing proprioception and cutaneous input in the presence of epidural stimulation and indicate that whether activation of tonic or rhythmic responses is generated depends on the specific combinations of sources and types of afferents activated in the hindlimb muscles.

scholarly journals Periodic modulation of repetitively elicited monosynaptic reflexes of the human lumbosacral spinal cord

2015 ◽  
Vol 114 (1) ◽  
pp. 400-410 ◽  
Author(s):  
Ursula S. Hofstoetter ◽  
Simon M. Danner ◽  
Brigitta Freundl ◽  
Heinrich Binder ◽  
Winfried Mayr ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Muscle Group ◽  
Lower Limbs ◽  
Spinal Reflex ◽  
Data Sets ◽  
Epidural Stimulation ◽  
Lumbosacral Spinal Cord ◽  
Cord Injury ◽  
Muscle Groups ◽  
Complete Spinal Cord Injury

In individuals with motor-complete spinal cord injury, epidural stimulation of the lumbosacral spinal cord at 2 Hz evokes unmodulated reflexes in the lower limbs, while stimulation at 22–60 Hz can generate rhythmic burstlike activity. Here we elaborated on an output pattern emerging at transitional stimulation frequencies with consecutively elicited reflexes alternating between large and small. We analyzed responses concomitantly elicited in thigh and leg muscle groups bilaterally by epidural stimulation in eight motor-complete spinal cord-injured individuals. Periodic amplitude modulation of at least 20 successive responses occurred in 31.4% of all available data sets with stimulation frequency set at 5–26 Hz, with highest prevalence at 16 Hz. It could be evoked in a single muscle group only but was more strongly expressed and consistent when occurring in pairs of antagonists or in the same muscle group bilaterally. Latencies and waveforms of the modulated reflexes corresponded to those of the unmodulated, monosynaptic responses to 2-Hz stimulation. We suggest that the cyclical changes of reflex excitability resulted from the interaction of facilitatory and inhibitory mechanisms emerging after specific delays and with distinct durations, including postactivation depression, recurrent inhibition and facilitation, as well as reafferent feedback activation. The emergence of large responses within the patterns at a rate of 5.5/s or 8/s may further suggest the entrainment of spinal mechanisms as involved in clonus. The study demonstrates that the human lumbosacral spinal cord can organize a simple form of rhythmicity through the repetitive activation of spinal reflex circuits.

Using Forelimb EMG to Control an Electronic Spinal Bridge to Facilitate Hindlimb Stepping After Complete Spinal Cord Lesion

2011 ◽  
Author(s):  
Parag Gad ◽  
Jonathan Woodbridge ◽  
Igor Lavrov ◽  
Yury Gerasimenko ◽  
Hui Zhong ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Biceps Brachii ◽  
Detection Algorithm ◽  
Spinal Cord Transection ◽  
Emg Activity ◽  
Thoracic Spinal Cord ◽  
Epidural Stimulation ◽  
Lumbosacral Spinal Cord ◽  
Thoracic Spinal ◽  
Cord Injury

A complete spinal cord transection results in loss of all supraspinal motor control below the level of the injury. The neural circuitry in the lumbosacral spinal cord, however, can generate locomotor patterns in the hindlimbs of rats and cats with the aid of epidural stimulation and administration of serotoninergic agonists. We hypothesized that there are patterns of EMG signals from the forelimbs during quadrupedal locomotion that uniquely represent a signal for the “intent” to step with the hindlimbs. These observations led us to determine whether “indirect” volitional control of stepping can be restored after a complete spinal cord injury. We developed an electronic bridge that can trigger specific patterns of EMG activity from the forelimbs to enable quadrupedal stepping after a complete spinal cord transection in rats. We found dominant frequencies of 180–220 Hz in the EMG of forelimb muscles during active periods, whereas the frequencies were between 0–10 Hz when the muscles were inactive. A moving window detection algorithm was implemented in a small microprocessor to detect bilateral activity in the biceps brachii that then was used to initiate and terminate epidural stimulation. This detection algorithm was successful in detecting stepping under different pharmacological conditions and at various treadmill speeds and in facilitating quadrupedal stepping after a complete mid-thoracic spinal cord transection.

Epidural stimulation for cardiovascular function increases lower limb lean mass in individuals with chronic motor complete spinal cord injury

2020 ◽  
Vol 105 (10) ◽  
pp. 1684-1691
Author(s):  
Bonnie Legg Ditterline ◽  
Susan J. Harkema ◽  
Andrea Willhite ◽  
Sean Stills ◽  
Beatrice Ugiliweneza ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Lean Mass ◽  
Lower Limb ◽  
Cardiovascular Function ◽  
Epidural Stimulation ◽  
Cord Injury ◽  
Complete Spinal Cord Injury

scholarly journals The recovery of standing and locomotion after spinal cord injury does not require task-specific training

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Jonathan Harnie ◽  
Adam Doelman ◽  
Emmanuelle de Vette ◽  
Johannie Audet ◽  
Etienne Desrochers ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Specific Activity ◽  
Weight Bearing ◽  
Triceps Surae ◽  
Full Weight Bearing ◽  
Specific Training ◽  
Spinal Transection ◽  
Cord Injury ◽  
Complete Spinal Cord Injury

After complete spinal cord injury, mammals, including mice, rats and cats, recover hindlimb locomotion with treadmill training. The premise is that sensory cues consistent with locomotion reorganize spinal sensorimotor circuits. Here, we show that hindlimb standing and locomotion recover after spinal transection in cats without task-specific training. Spinal-transected cats recovered full weight bearing standing and locomotion after five weeks of rhythmic manual stimulation of triceps surae muscles (non-specific training) and without any intervention. Moreover, cats modulated locomotor speed and performed split-belt locomotion six weeks after spinal transection, functions that were not trained or tested in the weeks prior. This indicates that spinal networks controlling standing and locomotion and their interactions with sensory feedback from the limbs remain largely intact after complete spinal cord injury. We conclude that standing and locomotor recovery is due to the return of neuronal excitability within spinal sensorimotor circuits that do not require task-specific activity-dependent plasticity.

Electrical epidural stimulation of the cervical spinal cord: Implications for spinal respiratory neuroplasticity after spinal cord injury

2021 ◽  
Author(s):  
Ian G Malone ◽  
Rachel L Nosacka ◽  
Marissa A Nash ◽  
Kevin J Otto ◽  
Erica A Dale
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Neural Plasticity ◽  
Molecular Mechanisms ◽  
Cervical Spinal Cord ◽  
Motor Nucleus ◽  
Epidural Stimulation ◽  
Locomotor Function ◽  
Lumbosacral Spinal Cord ◽  
Cord Injury

Traumatic cervical spinal cord injury (cSCI) can lead to damage of bulbospinal pathways to the respiratory motor nuclei and consequent life-threatening respiratory insufficiency due to respiratory muscle paralysis/paresis. Reports of electrical epidural stimulation (EES) of the lumbosacral spinal cord to enable locomotor function after SCI are encouraging, with some evidence of facilitating neural plasticity. Here, we detail the development and success of EES in recovering locomotor function with consideration of stimulation parameters and safety measures to develop effective EES protocols. EES is just beginning to be applied in other motor, sensory, and autonomic systems; however, there has only been moderate success in preclinical studies aimed at improving breathing function after cSCI. Thus, we explore rationale for applying EES to the cervical spinal cord, targeting the phrenic motor nucleus for the restoration of breathing. We also suggest cellular/molecular mechanisms by which EES may induce respiratory plasticity including a brief examination of sex-related differences in these mechanisms. Finally, we suggest more attention be paid to the effects of specific electrical parameters that have been used in the development of EES protocols and how that can impact the safety and efficacy for those receiving this therapy. Ultimately, we aim to inform readers about the potential benefits of EES in the phrenic motor system and encourage future studies in this area.

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