Nina Welding | October 7, 2019
One of the first few scenes in “Chariots of Fire” cuts to a group of Olympians running along a beach with a sweeping instrumental playing in the background. Watching that group of athletes move together to the music, it’s easy to see the rhythm in what researchers call synchronized locomotion. This synchronization of limb movement is precisely what engineers and scientists have been trying to create as they work to develop autonomous robots and exoskeletons for treating patients with spinal cord injuries, devices that offer more responsive, more natural limb movements and are energy-efficient.
Since 1961 when the first modern evidence of the central pattern generator (CPG) was verified, neurobiologists have been studying its functions. Most recently, they identified a close resemblance between biological locomotion gaits and the phase patterns in coupled oscillatory networks. This resemblance is what inspired the work currently being conducted at the University of Notre Dame in collaboration with the Georgia Institute of Technology.
What is the CPG? A group of neural oscillators located in the spinal cord of vertebrates and in ganglions of invertebrates, the CPG produces rhythmic patterns like locomotion, breathing and chewing — physical functions that harmonize almost involuntarily. One of the unique qualities of the CPG is that, even though it receives simple input signals from the higher regions of the brain, those signals depend on small autonomous neural networks (local areas) to generate patterns rather than the whole nervous system. This is why a person automatically adjusts her gait when she feels a pebble in her shoe. The “feedback” that there is a pebble is a fact the entire body knows, but the foot adjusts without waiting for specific additional input from the brain. There is no time delay in the body’s motor control, and that’s one of the key elements that is still missing in today’s autonomous robots and exoskeleton development.
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