Skilled reach training enhances robotic gait training to restore overground locomotion following spinal cord injury in rats.

Rehabilitative training has been shown to improve motor function following spinal cord injury (SCI). Unfortunately, these gains are primarily task specific; where reach training only improves reaching, step training only improves stepping and stand training only improves standing. More troublesome is the tendency that the improvement in a trained task often comes at the expense of an untrained task.

Viscous field training induces after effects but hinders recovery of overground locomotion following spinal cord injury in rats.

Robotic-assisted gait training was able to improve the unassisted overground locomotion of rats following a cervical spinal cord injury. Specifically, four weeks of daily step training in the Robomedica Rodent Robotic Motor Performance System, where the device actively guided the hindlimbs through a pre-injury stepping pattern while the rats walked over a moving treadmill belt in a quadrupedal posture, was able to improve unassisted overground locomotion as measured by the CatWalk gait analysis device. Unfortunately the improvements were minimal.

A Novel Multi-Dimensional Analysis of Rodent Gait Reveals the Compensation Strategies Used during Spontaneous Recovery from Spinal Cord and Traumatic Brain Injury.

As rodent locomotion becomes a more popular behavioral assay, proper rodent gait analysis becomes more and more important. Gait measures, such as stride length, cycle time, and duty factor, are not independent of one another, making statistical comparisons between groups a tricky endeavor. Instead of identifying the mathematical relationships between a group of locomotor measures, we simply tracked the steps of rodents in space.

Novel spatiotemporal analysis of gait changes in body weight supported treadmill trained rats following cervical spinal cord injury.

Background: Common gait measures such as stride length, cycle time, and step height are not independent variables, but different aspects of the same multidimensional step. This complicates comparisons between experimental groups. Here we present a novel multidimensional gait analysis method and use this method to assess the ability of body weight supported treadmill training (BWSTT) to improve rodent stepping after spinal cord injury (SCI).

Addition of forelimb training reduces gains from robotic gait training in a rat model of spinal cord injury.

To restore locomotor function following spinal cord injury the disrupted descending supraspinal drive needs to be re-connected to regions caudal to the injury. Robotic gait training aims to facilitate recovery by stimulating the proprioceptive networks of the legs in a coordinated walking pattern while the descending supraspinal connections are re-established. In incomplete injuries, it is believed that the interneuronal networks near the injury site form relay circuits to reroute the supraspinal signals through the spared tissue.

Methods to quantify the velocity dependence of common gait measurements from automated rodent gait analysis devices.

Background: Walking slowly is a different biomechanical task than walking quickly, thus measures of gait will be different at different velocities, such as pre/post injury. It is necessary to determine if the difference in gait measures are from the experimental changes, or simply from traveling at different speeds.

New Method: Instead of limiting this effect, we have developed techniques to embrace the velocity dependence of gait measures.

Quantifying changes following spinal cord injury with velocity dependent locomotor measures.

Many locomotor measures commonly used to assess functional deficits following neurological injury are velocity dependent. This makes the comparison of faster pre-injury walking to slower post-injury walking a challenging process. In lieu of calculating mean values at specific velocities, we have employed the use of nonlinear regression techniques to quantify locomotor measures across all velocities.

Kinematic trajectories while walking within the Lokomat robotic gait-orthosis.

Background One of the most popular robot assisted rehabilitation devices used is the Lokomat. Unfortunately, not much is known about the behaviors exhibited by subjects in this device. The goal of this study was to evaluate the kinematic patterns of individuals walking inside the Lokomat compared to those demonstrated on a treadmill.

Abnormal joint torque patterns exhibited by chronic stroke subjects while walking with a prescribed physiological gait pattern.

Background: It is well documented that individuals with chronic stroke often exhibit considerable gait impairments that significantly impact their quality of life. While stroke subjects often walk asymmetrically, we sought to investigate whether prescribing near normal physiological gait patterns with the use of the Lokomat robotic gait-orthosis could help ameliorate asymmetries in gait, specifically, promote similar ankle, knee, and hip joint torques in both lower extremities. We hypothesized that hemiparetic stroke subjects would demonstrate significant differences in total joint torques in both the frontal and sagittal planes compared to non-disabled subjects despite walking under normal gait kinematic trajectories.

Quantification of functional weakness and abnormal synergy patterns in the lower limb of individuals with chronic stroke.

Background: The presence of abnormal muscle activation patterns is a well documented factor limiting the motor rehabilitation of patients following stroke. These abnormal muscle activation patterns, or synergies, have previously been quantified in the upper limbs. Presented here are the lower limb joint torque patterns measured in a standing position of sixteen chronic hemiparetic stroke subjects and sixteen age matched controls used to examine differences in strength and coordination between the two groups.

Spinal interneurons infected by renal injection of pseudorabies virus in the rat.

The potency of spinal sympathetic reflexes is increased after spinal injury, and these reflexes may result in life-threatening hypertensive crises in humans. Few, if any, primary afferents project directly to sympathetic preganglionic neurons (SPN). Therefore, spinal sympathetic interneurons (IN) must play a major role in generating dysfunctional sympathetic activity after spinal cord injury.

Locations and morphologies of sympathetically correlated neurons in the T(10) spinal segment of the rat.

We precisely localized and morphologically characterized sympathetically correlated neurons in the acutely transected spinal cord of the rat. We have shown that these neurons are likely members of the spinal networks that generate sympathetic activity after spinal cord transection. In humans with injured spinal cords, these networks are responsible for hypertensive crises that occur in response to ordinarily innocuous stimuli.