Effect of Treadmill Training Protocols on Locomotion Recovery in Spinalized Rats

Both treadmill training and epidural stimulation can help to reactivate the central pattern generator (CPG) in the spinal cord after a spinal cord injury. However, designing an appropriate training approach and a stimulation profile is still a controversial issue. Since the spinal afferent signals are the input signals of CPG in the spinal cord, it can be concluded that the number of input afferent signals can affect the quality of movement recovery, such a phenomenon is in accordance with Hebbian theory. Therefore, at first in this paper, through some simulation studies on a model of CPGs, the effective influence of increasing the afferent input weight on activating CPG model was certified. Then, the performance of two different types of treadmill training along with epidural stimulation was compared. The numbers of spinal afferents involved during each designed training approach were different. Experiments were conducted on two groups of spinalized rats. Three quantized integer qualitative measures, with 0–2 scales, were envisioned to evaluate the performance of training protocols. According to the experimental results, the assigned scales to the rats using the training approach involving more afferents, the rats have been creeping on a treadmill, was 2. Also, the assigned scales to the rats using the training approach involving less afferents, the rats have been performing bipedal locomotion, was 0 or 1. Such experimental results coincide with achieved simulation results elucidating the effect of increasing the afferent input weights on activating CPG model.