A method for assessing balance control in rodents

Recent research has shown that after spinal cord injury, the nervous system reorganizes. Nevertheless, little is known of the effects of neural reorganization, or plasticity, on motor skills. In this work, we present a method that utilizes kinetic and kinematic analysis, for investigating balance control in a rodent model of incomplete spinal cord injury. In this setup, the animals sit unconstrained on their hindlimbs on a platform while they eat a Fruitloop. In this posture, the animal is supporting all the body weight on its hindquarters removing the need for the animal to support itself on its hindlimb or maintain appropriate forelimb-hindlimb coordination for functional gait. The platform is bolted to a force transducer to provide measurements of shear forces in orthogonal directions in the horizontal plane. Reflective markers on the hip and tail of the animal indicate sway of the animals body. Using this method the effect of extensive 12 week long treadmill locomotor training on balance control in rodents with incomplete thoracic spinal cord contusion injury (iSCI) was assessed. One iSCI rat did not undergo training, while a sham injured and 3 other iSCI rats underwent training. The shear forces and sway produced by the injured untrained rat were much larger than for the sham or the injured but trained rats. Stance width assessed from overground walking in a separate study was also larger in the injured untrained rat. These data suggest that balance control may be improved by a locomotor training paradigm. This simple method for assessing balance control could thus be utilized in longitudinal studies to evaluate the effectiveness of pharmacological and locomotor therapies for repair and recovery after spinal cord injury.