Effects of Assist-as-needed Robotic Training Paradigms on the Locomotor Recovery of Adult Spinal Mice

Abstract

This paper introduces a new "assist-asneeded" (AAN) training paradigm for rehabilitation of spinal cord injuries via robotic training devices. In the pilot study reported in this paper, nine female adult Swiss-Webster mice were divided into three groups, each experiencing a different robotic training control strategy: a fixed training trajectory (Fixed Group, A), an AAN training method without interlimb coordination (Band Group, B), and an AAN training method with bilateral hindlimb coordination (Window Group, C). Fourteen days after complete transection at the mid-thoracic level, the mice were robotically trained to step in the presence of an acutely administered serotonin agonist, quipazine, for a period of six weeks. The mice that received AAN training (Groups B and C) show higher levels of recovery than Group A mice, as measured by the number, consistency, and periodicity of steps realized during testing sessions. Group C displays a higher incidence of alternating stepping than Group B. These results indicate that this training approach may be more effective than fixed trajectory paradigms in promoting robust post-injury stepping behavior. Furthermore, the constraint of interlimb coordination appears to be an important contribution to successful training. Presented in this paper are also some preliminary results from a recent full-scale study that complements the conclusions from this pilot study.

A review on human intent understanding and compliance control strategies for lower limb exoskeletons

“…Lance employed velocity field to realize AAN control. 110 Specifically, a virtual tunnel surrounding the desired trajectory was designed. When the ankle leaved the band, the convergent velocity fields would rapidly move it back into the band region.…”

Human-Robot Interfaces in Exoskeletons for Gait Training after Stroke: State of the Art and Challenges

“…Since a couple of years some rehabilitation devices are based on the assist-as-needed (AAN) strategy [10,11]. This strategy requires the user actively participate and the robotic device only assists or corrects the motions of the user.…”

“…The user tries to follow a path whereas the motions are executed in a "virtual tunnel", superimposing the original path. This tunnel limits the path error by increasing the impedance or an assistive force to push the limb back to its original path [5,10,17]. At the moment these strategies are being tested in different studies [4].…”

Game Theory

“…A more intuitive controller based on the "assist-as-needed" (AAN) paradigm is also widely used by movement-based rehabilitation robots. A comparison study of the efficacy of fixed trajectory algorithms against AAN algorithms on recovery of locomotion ability in completely spinalized adult mice was undertaken by Cai et al (2006). The results of this study show that mice undergoing AAN robotic training exhibited faster and more pronounced recovery than mice given fixed robotic training.…”