Researchers at Stanford University, Palo Alto, California, are making progress on techniques that control the leg muscles in mice. The hope is that someday this research could help restore functional muscle activity in people with paralysis and reduce muscle spasticity in individuals with cerebral palsy (CP).
The researcher’s report was published September 16 in the online edition of Nature Medicine (www.nature.com/nm/journal/v16/n10/full/nm.2228.html).
The technique requires pulses of light to activate proteins in photosynthetic algae, which in turn switch nerve cells on and off. The field is called optogenetics. As reported in NewScientist.com, the study is the first to apply the pulses of light technique to the part of the nervous system with control over voluntary movement.
Karl Deisseroth, PhD, MD, and colleagues anesthetized mice and then stimulated their sciatic nerves using a cuff lined with light-emitting diodes. Resulting contractions were then measured in their Achilles tendons.
In the past, electrical impulses have enabled the paralyzed to walk. But because electrical signals activate large, fast-twitch nerve fibers before slow-twitch nerve fibers-the opposite of what occurs naturally-the resulting gait pattern is jerky and robotic. Walking in this manner becomes fatiguing very quickly.
The Stanford study, in contrast, has reproduced the “natural firing order” of nerves in the mice, according to team member Scott Delp, PhD. The Stanford team hopes that using this technique could work in humans to restore movement in paralyzed limbs and help those with CP achieve a smoother, less exhausting gait pattern.
