Walking requires more than just stepping one foot in front of the other. Rather, it is a coordinated whole-body movement involving both the arms and legs. A recent study looks into this whole-body effort.

Research published recently in Neuron identified subpopulations of neurons in the spinal cord with long projections, which coordinate arm and leg movement and ensure a stable body posture while walking.

These specific, long projecting neurons, traversing our spinal cord, form an important basis for the coordination of fore- and hindlimbs. These neurons couple local networks over long distances and thereby ensure posture and rhythm of our body during locomotion, according to a media release from the University of Basel.

Silvia Arber at the Biozentrum of the University of Basel and the Friedrich Miescher Institute for Biomedical Research, who led the research team, suggests in the release that these insights may be important in the ability to restore functionality after a spinal cord injury.

Axons of most excitatory neurons cross the midline of the spinal cord and contact contralateral networks. In contrast, inhibitory neurons project predominantly on the same side of the body. The diagonal and mirrored pattern of the excitatory neuronal connections is very interesting when observing the coordination of arms and legs in a runner as Usain Bolt, the release explains.

To demonstrate the importance of long projection neurons in the spinal cord for the walking pattern, the researchers selectively eliminated those neurons. Interestingly, local movement patterns within a single limb remain however unaffected. This reinforces the specific role of long projecting neurons in the regulation of whole body movement.

The research team then observed that the neurons with long projections broadcast their signals throughout the spinal cord and receive extensive input from various brain regions. This organization of long projection neurons and their connections places them at an important intersection between integrating information from the brain and distributing it in the spinal cord, the release continues.

“The results of our new study show that long projecting neurons in the spinal cord exhibit a very important role for the coordination of the locomotor pattern,” Arber explains. “Henceforth, we plan to investigate how the brain interacts differently with local and long projecting spinal neurons to control them specifically.”

[Source(s): University of Basel, Science Daily]