The researchers studied the signals the central nervous system uses to control muscles and locomotion. To do this, they compared the neuronal activity produced by 20 skeletal muscles in children who are already walking and in adults, versus the “reflex gait” of neonates. They observed that babies, three days after birth, when held upright on a surface and displaced, try to take steps. To do this, they activate neurons in the spinal cord in two phases: the first ordering the legs to bend and extend, and the second to move them forward.
When they begin to walk independently (at one year old), the neural circuit works in four phases. In addition to the previous two, mechanisms are added to control certain nuances of movement, such as lifting the heel before bending the leg. Neural reactions very similar to these were seen in cats, rats, macaques, and guinea fowls. The discoveries indicate that it is after these first steps that human development differs from other animals. “Preschool children (two to four years) showmodels of transition between the moment when they start to walk and adults“explains to SINC Francesco Lacquaniti, co-author of the work published by Science and a researcher at the University of Rome Tor Vergata (Italy).
The results indicate that thismovement of humans and other animals comes from a neural network of a common ancestor. “The evolution of these animal species probably diverged more than 100 million years ago. Perhaps the neural circuits that generate locomotion emerged during the evolutionary process from a common ancestor”, interprets the scientist.
The team believes that these findings may help design better tools for rehabilitation, functional electrical stimulation, and prosthetics for patients with spinal cord damage.
