Review Article
Yoram Baram
Abstract
Background: External entrainment of gait in patients with Parkinson's disease by a constantly moving visual cue or by a rhythmic auditory cue has been proposed and extensively studied. We have found that such entrainment, having positive effects on some of the patients, also has adverse effects, such as freezing of gait, on others. Methods and findings: Closed-loop autonomous entrainment by visual or auditory feedback, generated by the patient's own movement, is found to be inherently stable, whereas open-loop external entrainment is inherently unstable. Autonomous entrainment is found to be not only dopamine rewarding, but also embedding, by learning, reward seeking behavior. Enhanced by environmental novelty and cognitive vigilance, such behavior is found to have a more pronounced expression under higher dimensional geometric feedback. Results: Reviewed clinical studies show a considerably higher gait improvement, without adverse effects, under autonomous entrainment than under external entrainment, having adverse effects. Considerably higher improvement is produced by two-dimensional checkerboard tiles than by one-dimensional transverse lines. Gait improvement by autonomous entrainment is found to apply to a variety of neurological disorders. Conclusion: Autonomous gait entrainment and higher dimensional visual feedback produce highly pronounced gait improvement, transformative across space, time and different neurological disorders.