Abstract

The role of the spinal cord is often simplified to that of a simple relay station that relays messages between the brain and the body. However, the spinal cord can actually learn and remember movements on its own. Although there is evidence of “learning” within the spinal cord from experiments dating back to the early 20th century, the question of which neurons are involved and how they encode this learning experience has remained unanswered. To investigate how the spinal cord learns, researchers built an experimental system to measure changes in movement in mice, inspired by methods used in insect studies. They were able to assess the contribution of six different neuronal populations and identified two groups of neurons, one dorsal and one ventral, that mediate motor learning. These two groups of neurons alternate in their functions. The dorsal neurons help the spinal cord learn a new movement, while the ventral neurons help the spinal cord remember and perform the movement later. “You can compare it to a relay race inside the spinal cord. The dorsal neurons act like the first runner, passing on the sensory information that is important for learning. Then the ventral neurons take over, ensuring that the learned movement is remembered and executed smoothly.”The researchers’ findings show that neural activity in the spinal cord resembles different classical types of learning and memory. Uncovering these learning mechanisms will be crucial, opening up new avenues for rehabilitation strategies after spinal cord injuries and rethinking how to approach movement recovery in patients with spinal damage.

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