eldavojohn notes a paper released in Nature Neuroscience today describing work in which paraplegic rats were enabled to walk again as early as a week after injury and treatment. The process involves a serotonin-influencing drug and electrical stimulation of the spine, along with an incentive to the paralyzed back legs to move — namely, being placed on a treadmill. Soon a poorly understood spinal mechanism called the "central pattern generator" kicks in and the rats' legs move under the stimulus of a rhythmic signal from the spine (the brain is not involved). Eurekalert reports, "Daily treadmill training over several weeks eventually enabled the rats to regain full weight-bearing walking, including backwards, sideways and at running speed. However, the injury still interrupted the brain's connection to the spinal cord-based rhythmic walking circuitry, leaving the rats unable to walk of their own accord."