The use of a robotic body weight support mechanism to improve outcome assessment in the spinal cord injured rodent

摘要

This paper describes the use of a robotic device to assess rodent locomotor ability following spinal cord injury by quantifying the amount of external body weight support required by the animal to step on a treadmill. Precisely controlled, upward forces were delivered to the rat torso through the use of a specially designed counterbalance system. The system utilized an electric motor to alter spring tension in a specific kinematic configuration, which enabled support to be changed rapidly (within a step) in order to adapt to the animal's specific needs, or to challenge the animal's capability. Spinal cord transected rats were trained to step while the amount of external body weight support was progressively decreased during several minutes of locomotion on a treadmill, i.e. the rats increasingly supported more of their own body weight. Each animal failed to step at a consistent amount of weight assistance (test-retest reliability=0.92). During three months of daily training, the rats demonstrated an improvement in their ability to support body weight (p=0.04). The system's unique ability to precisely quantify body weight support allows for a continuous measurement of what was previously a binary assessment, i.e. the animal can support body weight or it cannot, and augments the information derived from current outcome measurement techniques.