Sensing Movement

The quest to restore movement to those who have lost it—or some portion of it—to neurological diseases and disorders is as daunting as it is noble. Many of the first generation of neural engineers and functional electrical stimulation researchers concentrated their attention at the site of the dysfunction, or at the neural fibers that control the affected muscles. While this strategy has produced a wealth of success and restoration of much function to thousands of people, it is not without its shortcomings. For example, many of the early research subjects who received standing or walking prostheses to treat paralysis lacked the sensory input needed to provide feedback to the motor control system. Maintaining stationary balance and postural control proved to be nearly as challenging a task as restoring locomotion.

Fortunately, there are alternative strategies underway that may dramatically enhance the prospect of restoring function to people with spinal cord injury, stroke, Parkinson’s disease, dystonia, traumatic brain injury, and other disorders. One of the most interesting examples we have seen is Afferent Corp.’s sensory stimulation technology, which targets the mechanoreceptors present throughout the somatasensory sensory system [see article, p1]. This approach not only promises to help restore lost sensation—a detriment many disabled people rate as significant as lost movement—it may also be the key to restoring coordinated movement.

Another form of sensory stimulation, involving the vestibular system—sometimes called our sixth sense—may have a similar effect on restoring movement [see article, p1]. This is because the central nervous system depends upon the detection of motion and acceleration in order to control movement most effectively.
In another example, the “sensory motor retuning” therapy developed at the University of Konstanz [see article, p5] shows that movement disorders such as focal dystonia can be effectively treated by including a consideration of sensory mapping from the affected area to the somatosensory cortex. Afferent Corp.’s informal motto, “Think Cortically, Act Peripherally,” seems all the more apropos in this context.

Finally, neural engineers should not neglect the strategy undertaken by Victhom Human Bionics to integrate neural control with prosthetic devices [see profile, p7] as a powerful strategy for restoring movement to disabled individuals. Ultimately, this may offer the most readily achievable and naturally functioning solution for a wide range of disabilities, particularly as efforts to “osseointegrate” limb prostheses with bones achieve progress.

Taken in total, these new approaches to restoring function represent a movement that makes sense.

James Cavuoto
Editor and Publisher