(Baltimore, MD) - In a study published in the August issue of Nature Neuroscience, researchers at the Kennedy Krieger Institute in Baltimore, Maryland found that there are separate adaptable networks controlling each leg and there are also separate networks controlling leg movements, e.g., forward or backward walking. These findings are contrary to the currently accepted theory that leg movements and adaptations are directed by a single control circuit in the brain. The ability to train the right and left legs independently opens the door to new therapeutic approaches for correcting walking abilities in patients with brain injury (e.g., stroke) and neurological disorders (e.g., cerebral palsy and multiple sclerosis).
Using a split-belt treadmill to separately control the legs, Kennedy Krieger researchers Dr. Amy Bastian and Julia Choi studied forty healthy adults and tracked each persons ability to learn various walking exercises. Utilizing specialized computer software and infrared tracking devices placed on key joints, researchers found subjects could store different walking patterns for forward versus backward walking simultaneously, with no interference between the two, revealing that separate brain systems control the two directions of walking. Surprisingly, people could also walk easily with one leg moving forward and the other backward, a pattern referred to as hybrid walking. Adaptation of hybrid walking, in which varying speeds were applied to legs walking in opposite directions, was found to interfere with subsequent normal forward and backward walking. The combined results demonstrate there are distinct brain modules responsible for right/forward, right/backward, left/forward and left/backward walking. Most significantly, these modules can be individually trained, which would be critical for rehabilitation focused on correcting walking asymmetries produced by brain damage.