The spinal cord, that nerve tissue that can learn and remember

It runs like a headless chicken… But how can a gallic bird with its head barely cut off make a furious but fleeting race? The key to the enigma, found in the early 20th century^e century, nestling in the spinal cord. Because if the unfortunate bird, once cut down, can sprint, it is because the network of neurons located in its vertebrae is functioning autonomously – even if it is deprived of commands sent by the brain and peripheral sensory stimuli.

this “ The musculature of the spinal cord continues to be active even when the nerve connection to the brain is interrupted, such as after a spinal cord injury. It can produce rhythmic nerve impulses that coordinately activate neurons (“motoneurons”), which in turn stimulate leg muscles. Through this network, the spinal cord plays a central role in rapid coordination, adaptation, and automation. walk

in paraplegic patients, “All spinal neuroprostheses used to restore movement form are based on stimulation of this network”explains Ervan Bezard, a neuroscientist at the University of Bordeaux (Inserm-CNRS).

But the spinal cord does even more amazing things. It appears to have motor learning and memorization abilities…independent of the brain! Abilities identified in mice, in Journal Science On April 11, by the teams of Belgium and Japan. Even better, the researchers identified and characterized two types of neurons that provide this learning and this “memory”, respectively.

“More than just a hit”

“The spinal cord is too often thought of as a simple tube that transmits information between the brainstem and the muscles that carry out the movements.Condemns Simon Laveau, a French PhD student who conducted most of the experiments at the Catholic University of Leuven (KU Leuven, Belgium). Our research shows it does much more. »

Since 1962, it has been known that legs in headless insects can be trained to avoid external cues. In the 1990s, a similar phenomenon was observed in frogs and rats. A team from Louvain traveled here to dismantle the mounts of this mechanism. for two purposes: “Understanding the basics of motor automation in healthy people and improving the recovery of patients with spinal cord injuries”explains Aya Takeoka, who coordinated the research and who now works at the Riken Brain Research Center in Japan.