Regulation of Posture and Locomotion in Decerebrate and Spinal Animals

Musienko, Pavel; Gorskii, Oleg; Kilimnik, V. A.; Kozlovskaya, I. B.; Courtine, Grégoire; Edgerton, V. Reggie; Gerasimenko, Yu. P.

doi:10.1007/s11055-015-0062-3

Cited by 9 publications

(8 citation statements)

References 30 publications

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“…Therefore, during locomotion spinal and/or brainstem circuits anticipate (feed-forward) the requirements to maintain balance during the subsequent steps, demonstrating “planned” locomotor commands to generate the necessary propulsion and balance in a highly automatic mode. Subsequent experiments suggested a similar phenomenon in mid-thoracic spinal cats (Musienko and others 2015). …”

Section: Feed-forward Regulation Of Equilibrium During Locomotor Behamentioning

confidence: 81%

Feed-Forwardness of Spinal Networks in Posture and Locomotion

et al. 2016

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We present a new perspective on the concept of feed-forward compared to feedback mechanisms for motor control. We propose that conceptually all sensory information in real time provided to the brain and spinal cord can be viewed as a feed-forward phenomenon. We also propose that the spinal cord continually adapts to a broad array of ongoing sensory information that is used to adjust the probability of making timely and predictable decisions of selected networks that will execute a given response. One interpretation of the term feedback historically entails responses with short delays. We propose that feed-forward mechanisms, however, range in timeframes of milliseconds to an evolutionary perspective, that is, “evolutionary learning.” Continuously adapting events enable a high level of automaticity within the sensorimotor networks that mediate “planned” motor tasks. We emphasize that either a very small or a very large proportion of motor responses can be under some level of conscious vs automatic control. Furthermore, we make a case that a major component of automaticity of the neural control of movement in vertebrates is located within spinal cord networks. Even without brain input, the spinal cord routinely uses feed-forward processing of sensory information, particularly proprioceptive and cutaneous, to continuously make fundamental decisions that define motor responses. In effect, these spinal networks may be largely responsible for executing coordinated sensorimotor tasks, even those under normal “conscious” control.

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Section: Feed-forward Regulation Of Equilibrium During Locomotor Behamentioning

confidence: 81%

Feed-Forwardness of Spinal Networks in Posture and Locomotion

et al. 2016

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“…Training-induced modulation of evoked potentials recorded while subjects are standing, sitting, and supine Previous studies highlighted the fact that somatosensory information from the lower limbs play a significant role in modulating the motor output generated during standing and stepping with and without epidural stimulation in mammals. 7,24,[56][57][58] We have also previously shown that the sensory information related to the transition from sitting to standing promoted the generation of EMG patterns sufficient for standing, increasing EMG amplitude in most of the lower limb muscles. 9,28 The results reported in the present study also showed that sensory information related to the change in body position from sitting to standing, without any change in the stimulation parameters, promoted an increased amplitude of the evoked potentials recorded from several lower limb muscles (Fig.…”

Section: Stand and Step Training With Epidural Stimulation Differentimentioning

confidence: 85%

“…42,43 However, the stimulation parameters (i.e., site, electrode configuration, frequency, amplitude) are crucial determinants of the extent and proportion of the modulation of these sensory-motor pathways as well as of the motor output generated in rats 26,27,42 and humans. 28,33 For example, when motor complete SCI individuals were epidurally stimulated at a higher intensity in supine position, stimulation frequencies between 5 and 15 Hz were found optimal to elicit a tonic extensor motor pattern of the lower limbs, whereas a rhythmic EMG pattern was induced by higher frequencies (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31) without any adjustment in stimulation site or intensity. 33 These results were interpreted as meaning that different stimulation frequencies at the same site of stimulation would access different inhibitory and/or excitatory pathways within the spinal cord networks to elicit different EMG patterns (i.e., rhythmic vs. tonic).…”

Section: Epidural Stimulationmentioning

confidence: 99%

“…Epidural stimulation of the lumbosacral spinal cord after complete SCI has been successfully applied to facilitate standing in mammals. [24][25][26][27] These studies demonstrated that, in the absence of supraspinal input, epidural stimulation of the lumbosacral spinal cord can promote motor output effective for standing, and that sensory afferent input as well as a fine tuning of the different stimulation parameters (i.e., stimulation site, frequency, and amplitude) are crucial to control it. More recently, we have demonstrated that four out of four chronic complete paraplegics (two graded as American Spinal Injury Association Impairment Scale [AIS] A and two graded as AIS B) were able to stand overground while epidurally stimulated, bearing full body weight without any external assistance at the knees and using their hands to assist balance.…”

Section: Introductionmentioning

confidence: 98%

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Effects of Stand and Step Training with Epidural Stimulation on Motor Function for Standing in Chronic Complete Paraplegics

Rejc

Angeli

Bryant

et al. 2017

Journal of Neurotrauma

109

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Individuals affected by motor complete spinal cord injury are unable to stand, walk, or move their lower limbs voluntarily; this diagnosis normally implies severe limitations for functional recovery. We have recently shown that the appropriate selection of epidural stimulation parameters was critical to promoting full-body, weight-bearing standing with independent knee extension in four individuals with chronic clinically complete paralysis. In the current study, we examined the effects of stand training and subsequent step training with epidural stimulation on motor function for standing in the same four individuals. After stand training, the ability to stand improved to different extents in the four participants. Step training performed afterwards substantially impaired standing ability in three of the four individuals. Improved standing ability generally coincided with continuous electromyography (EMG) patterns with constant levels of ground reaction forces. Conversely, poorer standing ability was associated with more variable EMG patterns that alternated EMG bursts and longer periods of negligible activity in most of the muscles. Stand and step training also differentially affected the evoked potentials amplitude modulation induced by sitting-to-standing transition. Finally, stand and step training with epidural stimulation were not sufficient to improve motor function for standing without stimulation. These findings show that the spinal circuitry of motor complete paraplegics can generate motor patterns effective for standing in response to task-specific training with optimized stimulation parameters. Conversely, step training can lead to neural adaptations resulting in impaired motor function for standing.

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“…However, functional load through weight-bearing has been widely shown to play a significant role in modulating the motor pattern generated during stepping [ 11 , 35 – 39 ] and standing with and without epidural stimulation in mammals. Decerebrated and spinalized cats showed the ability to exert efficient postural control during standing and stepping in the presence of epidural stimulation [ 40 , 41 ]. In these studies, the suppression of vestibular, visual, and head-neck-trunk sensory input implies that the motor responses were driven by somatosensory information from the lower limbs, highlighting the importance of afferent information in modulating motor output.…”

Section: Discussionmentioning

confidence: 99%

Effects of Lumbosacral Spinal Cord Epidural Stimulation for Standing after Chronic Complete Paralysis in Humans

2015

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Sensory and motor complete spinal cord injury (SCI) has been considered functionally complete resulting in permanent paralysis with no recovery of voluntary movement, standing or walking. Previous findings demonstrated that lumbosacral spinal cord epidural stimulation can activate the spinal neural networks in one individual with motor complete, but sensory incomplete SCI, who achieved full body weight-bearing standing with independent knee extension, minimal self-assistance for balance and minimal external assistance for facilitating hip extension. In this study, we showed that two clinically sensory and motor complete participants were able to stand over-ground bearing full body-weight without any external assistance, using their hands to assist balance. The two clinically motor complete, but sensory incomplete participants also used minimal external assistance for hip extension. Standing with the least amount of assistance was achieved with individual-specific stimulation parameters, which promoted overall continuous EMG patterns in the lower limbs’ muscles. Stimulation parameters optimized for one individual resulted in poor standing and additional need of external assistance for hip and knee extension in the other participants. During sitting, little or negligible EMG activity of lower limb muscles was induced by epidural stimulation, showing that the weight-bearing related sensory information was needed to generate sufficient EMG patterns to effectively support full weight-bearing standing. In general, electrode configurations with cathodes selected in the caudal region of the array at relatively higher frequencies (25–60 Hz) resulted in the more effective EMG patterns for standing. These results show that human spinal circuitry can generate motor patterns effective for standing in the absence of functional supraspinal connections; however the appropriate selection of stimulation parameters is critical.

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Regulation of Posture and Locomotion in Decerebrate and Spinal Animals

Cited by 9 publications

References 30 publications

Feed-Forwardness of Spinal Networks in Posture and Locomotion

Feed-Forwardness of Spinal Networks in Posture and Locomotion

Effects of Stand and Step Training with Epidural Stimulation on Motor Function for Standing in Chronic Complete Paraplegics

Effects of Lumbosacral Spinal Cord Epidural Stimulation for Standing after Chronic Complete Paralysis in Humans

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