Spinal Cord's Hidden Role in Learning Movement

A common misconception is that the spinal cord serves as a basic relay station that transmits signals from the brain to the body. But in reality, the spinal cord is capable of learning and remembering movements on its own.

Two distinct neuronal populations allow the spinal cord to adapt and recall learned behavior in a way that is entirely independent of the brain, according to research from a team at the Leuven-based Neuro-Electronics Research Flanders (NERF).

These exciting new results provide fresh insight into the potential role of spinal circuits in the learning and automation of movement. They were published today in Science. These observations may be useful in the rehabilitation of patients who have suffered spinal injuries.

The Spinal Cord’s Puzzling Plasticity

Without input from the brain, the spinal cord integrates various sources of sensory information to modulate and fine-tune the actions and movements. Furthermore, with enough repeated practice, nerve cells in the spinal cord can learn to adapt to different tasks on their own. However, neuroscientists have been perplexed by how the spinal cord manages to achieve this extraordinary plasticity for decades.

Aya Takeoka is a Professor of Neuroscience. Takeoka group investigates how nerve connections are wired, how they function, and how they alter when researchers learn new movements to understand better how the spinal cord heals from injuries. (NERF is a research institute supported by imec, KU Leuven, and VIB.)

Although we have evidence of ‘learning’ within the spinal cord from experiments dating back as early as the beginning of the 20th century, the question of which neurons are involved and how they encode this learning experience has remained unanswered.”

Aya Takeoka, Professor, Neuroscience, Neuro-Electronics Research Flanders

A portion of the issue stems from the challenge of precisely assessing the activity of individual spinal cord neurons in awake, moving animals without sedation. Takeoka's group exploited a model where animals can learn particular movements in a matter of minutes. Thus, the team discovered a mechanism of spinal cord learning that is specific to cell types.

Two Specific Neuronal Cell Types

Inspired by techniques used in insect studies, Ph.D. Student Simon Lavaud and colleagues at the Takeoka lab constructed an experimental setup to measure changes in movement in mice to investigate how the spinal cord learns.

We evaluated the contribution of six different neuronal populations and identified two groups of neurons, one dorsal and one ventral, that mediate motor learning. These two sets of neurons take turns. The dorsal neurons help the spinal cord learn a new movement, while the ventral neurons help it remember and perform the movement later.”

Simon Lavaud, Ph.D. Student, Takeoka Lab, Department of Neuroscience and Leuven Brain Institute

Lavaud said, “You can compare it to a relay race within the spinal cord. The dorsal neurons act like the first runner, passing on the critical sensory information for learning. Then, the ventral cells take the baton, ensuring the learned movement is remembered and executed smoothly.”

Learning and Memory Outside the Brain

Inspired by techniques used in insect studies, Ph.D. Student Simon Lavaud and colleagues at the Takeoka lab constructed an experimental setup to measure changes in movement in mice to investigate how the spinal cord learns, and may also be relevant in the context of rehabilitation,

Prof. Aya Takeoka said, “The circuits we described could provide the means for the spinal cord to contribute to movement learning and long-term motor memory, which both help us to move, not only in normal health but especially during recovery from brain or spinal cord injuries.”