A novel device for studying weight supported, quadrupedal overground locomotion in spinal cord injured rats

Providing weight support facilitates locomotion in spinal cord injured animals. To control weight support, robotic systems have been developed for treadmill stepping and more recently for overground walking.

We developed a novel device, the body weight supported ambulatory rodent trainer (i.e. BART). It has a small pneumatic cylinder that moves along a linear track above the rat. When air is supplied to the cylinder, the rats are lifted as they perform overground walking. We tested the BART device in rats that received a moderate spinal cord contusion injury and in normal rats. Locomotor training with the BART device was not performed.

All of the rats learned to walk in the BART device. In the contused rats, significantly greater paw dragging and dorsal stepping occurred in the hindlimbs compared to normal. Providing weight support significantly raised hip position and significantly reduced locomotor deficits. Hindlimb stepping was tightly coupled to forelimb stepping but only when the contused rats stepped without weight support. Three weeks after the contused rats received a complete spinal cord transection, significantly fewer hindlimb steps were performed.

Relative to rodent robotic systems, the BART device is a simpler system for studying overground locomotion. The BART device lacks sophisticated control and sensing capability, but it can be assembled relatively easily and cheaply.

These findings suggest that the BART device is a useful tool for assessing quadrupedal, overground locomotion which is a more natural form of locomotion relative to treadmill locomotion.