Use of quadrupedal step training to re-engage spinal interneuronal networks and improve locomotor function after spinal cord injury

Abstract

Can lower limb motor function be improved after a spinal cord lesion by re-engaging functional activity of the upper limbs? We addressed this issue by training the forelimbs in conjunction with the hindlimbs after a thoracic spinal cord hemisection in adult rats. The spinal circuitries were more excitable, and behavioural and electrophysiological analyses showed improved hindlimb function when the forelimbs were engaged simultaneously with the hindlimbs during treadmill step-training as opposed to training only the hindlimbs. Neuronal retrograde labelling demonstrated a greater number of propriospinal labelled neurons above and below the thoracic lesion site in quadrupedally versus bipedally trained rats. The results provide strong evidence that actively engaging the forelimbs improves hindlimb function and that one likely mechanism underlying these effects is the reorganization and re-engagement of rostrocaudal spinal interneuronal networks. For the first time, we provide evidence that the spinal interneuronal networks linking the forelimbs and hindlimbs are amenable to a rehabilitation training paradigm. Identification of this phenomenon provides a strong rationale for proceeding toward preclinical studies for determining whether training paradigms involving upper arm training in concert with lower extremity training can enhance locomotor recovery after neurological damage.

Treadmill training induced lumbar motoneuron dendritic plasticity and behavior recovery in adult rats after a thoracic contusive spinal cord injury

“…Clinical evidence supports the notion that treadmill training can improve ambulation ability in SCI patients (Lusilla-Palacios et al, 2013;Mirbagheri et al, 2013;Shah et al, 2013).…”

“…However, active exercise and rehabilitation regimens have demonstrated some success at restoring locomotor ability in incomplete SCI, and that altered neural plasticity may contribute to recovery (Jung et al, 2014;Martinez et al, 2013;Shin et al, 2014;Yang et al, 2014). Previous studies have applied targeted exercise or rehabilitation regimens spanning 5-6 weeks upon initiation of SCI (Shah et al, 2012(Shah et al, , 2013Weishaupt et al, 2013) though some locomotorbased training models have extended to 12 weeks in length (Multon et al, 2003).…”

Functional Neurorehabilitation - The Locomotor Quadrupedal Animal Training Adapted to the Bipedal Human

“…The LT in quadruped animal, after section of the spinal cord, must take into account the forelimbs, as these influence the recovery of the hind limbs, being the synchronized training of the forelimbs with the hindlimbs more effective than bipedal training (exclusively of the hind limbs) (Shah P., Gerasimenko, Roy, & Tillakaratne, 2013).…”

The importance of the quadruped animal model in functional neurorehabilitation in the human biped

“…ES and IS being potentiated together means that they have different neural mechanisms: ES promotes stimulation of the dorsal lumbosacral spinal cord intumescence, and therefore of the reflex arc, allowing a motion gait with the hind limbs on the treadmill, although not rhythmically synchronized with the forelimb; whilst IS promotes the stimulation of the propriospinal pathways, associated or not with the locomotor areas of the brainstem. Hence, the simultaneous activation of ES and IS allows the engagement of interneural population which regulates locomotion (Lavron et al, 2015;Shah et al, 2013).…”