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Published October 11, 2006 | Published
Journal Article Open

Implications of assist-as-needed robotic step training after a complete spinal cord injury on intrinsic strategies of motor learning


Robotic training paradigms that enforce a fixed kinematic control might be suboptimal for rehabilitative training because they abolish variability, an intrinsic property of neuromuscular control (Jezernik et al., 2003). In the present study we introduce "assist-as-needed" (AAN) robotic training paradigms for rehabilitation of spinal cord injury subjects. To test the efficacy of these robotic control strategies to teach spinal mice to step, we divided 27 adult female Swiss–Webster mice randomly into three groups. Each group was trained robotically by using one of three control strategies: a fixed training trajectory (Fixed group), an AAN training paradigm without interlimb coordination (Band group), and an AAN training paradigm with bilateral hindlimb coordination (Window group). Beginning at 14 d after a complete midthoracic spinal cord transection, the mice were trained daily (10 min/d, 5 d/week) to step on a treadmill 10 min after the administration of quipazine (0.5 mg/kg), a serotonin agonist, for a period of 6 weeks. During weekly performance evaluations, the mice trained with the AAN window paradigm generally showed the highest level of recovery as measured by the number, consistency, and periodicity of steps during the testing sessions. In all three measurements there were no significant differences between the Band and the Fixed training groups. These results indicate that the window training approach, which includes loose alternating interlimb coordination, is more effective than a fixed trajectory paradigm with rigid alternating interlimb coordination or an AAN paradigm without any interlimb constraints in promoting robust postinjury stepping behavior.

Additional Information

© 2006 Society for Neuroscience. Received May 29, 2006; revised Aug. 16, 2006; accepted Aug. 20, 2006. This work was supported by grants from the Christopher Reeve Foundation, the National Institute of Child Health and Human Development (HD44830), and the National Institute of Neurological Disorders and Stroke (NS16333). We thank Hui Zhong for her assistance with animal surgeries; Maynor Herrera for providing excellent animal care; Niranjala Tillakaratne, John Hodgson, Rebekah Molyneux, and Sharon Zdunowski for their constructive comments and valuable discussions; and an incredible team of undergraduate students, Vivek Agarwal, Michael Andrew, Nikhil Daga, Armen Derian, Annie Kao, Dan Popa, Liliana Lacayo, and Traci Shiraishi, for all of their hard work.

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