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Amnésie sensorimotrice et mémoire musculaire

Most people are familiar with the concept of muscle memory. When we repeat a movement like swinging a golf club over and over, the neurons involved in controlling that movement develop increasingly stronger connections. Existing synapses begin to fire more efficiently, and new synapses are formed as well. As a result, our golf swing becomes more automatic, reliable and forceful the more often we practice. So, both the function and the actual structure of our brain adapts based on the movements and activities that we choose to do on a regular basis.

Despite what the term implies, muscles do not have memory of their own—they’re controlled by the nervous system. Our nervous system likes to be as efficient as possible, because making fast decisions helps us survive. So when our nervous system notices that we keep repeating the same movement or posture, it begins to make that movement or posture automatic.

When we’re first learning a new movement pattern, it’s mainly controlled by the prefrontal cortex of our brain—the area of the cerebral cortex that plans complex behavior, makes decisions, and focuses attention. As the movement pattern gradually becomes more automatic, the control of the pattern shifts through different areas of the brain, finally becoming a long-term motor memory when it consolidates to the vestibular nuclei in the brainstem. This is the process of developing muscle memory. This process allows the parts of brain responsible for making voluntary decisions to focus on new things that require conscious attention.

The process of developing muscle memory is not limited to athletes, nor is it limited to the learning of complex movement patterns like swinging a golf club. The same learning process is going on all the time within your nervous system, every day of your entire life, even if you sit at a desk all day and go home and watch TV at night.

Certaines personnes choisissent consciemment de travailler avec leur mémoire musculaire, s'entraînant et réentraînant activement leurs schémas musculaires dans la poursuite d'un objectif. Mais la plupart de us ne sommes pas conscients que nous sommes engagés dans un processus constant de renforcement inconsciemment d'anciens schémas de mouvement et d'apprentissage de nouveaux.

Ce processus d'apprentissage automatique est inné chez tous us, et il sert un objectif évolutif important. Vous pouvez imaginer à quel point la mémoire musculaire était essentielle à notre survie il y a des centaines de milliers d'années. À l'époque, seule la crise survivait et la capacité de se déplacer rapidement et automatiquement sous le stress signifiait souvent la différence entre la vie et la mort.

For most of us today, our survival is not so dependent on being able to move quickly. However, the process of learning and automating muscular patterns is hardwired into our nervous system, so it occurs whether we want it to or not. For the most part, developing muscle memory is enormously beneficial, allowing us to move through our daily life efficiently without having to think about mundane tasks like how to brush our teeth or prepare breakfast.

The key to avoiding problems is that we need to be aware of when we are developing muscular habits that might damage our body or lead to chronic pain. Since our nervous system wants to help us be as efficient as possible, it will remember any movement or posture that we choose to repeat—even if the movement or posture is unnatural and could potentially cause pain and damage over time.

Sensorimotor Amnesia

This brings us to the concept of sensorimotor amnesia. Thomas Hanna, the man who developed Clinical Somatic Education, coined this term to describe the loss of sensation and motor control that occurs as we learn muscular patterns. As we learn a movement or posture, not only does the control of that movement or posture become automatic and involuntary, but we lose sensation of the movement or posture. Our proprioceptive and vestibular systems gradually adapt so that we are unaware that the muscular pattern is even occurring.

Par exemple, si nous nous asseyons affalés devant notre ordinateur jour après jour, notre système nerveux apprend à garder us dans cette posture affaissée en gardant certains muscles contractés, et nos systèmes proprioceptifs et vestibulaires permettent us de plus en plus à l'aise dans cette position peu naturelle. Se pencher vers l'avant commence à se sentir normal et même bien, et s'asseoir droit demande des efforts et est inconfortable. Nous restons généralement parfaitement inconscients de cette adaptation subconsciente jusqu'à ce qu'un jour, elle provoque finalement us la douleur.

So, sensorimotor amnesia describes the negative effects of developing muscle memory; the state in which we have lost sensation and voluntary control of a movement or posture because it has become so deeply learned.

Now that you’ve spent this time thinking about muscle memory, and now that you know what sensorimotor amnesia is, you’ll probably start noticing your habitual patterns more and more. You might start to notice that you round your shoulders forward when you’re working at the computer, and that it feels natural to sit like that. You might notice that you always reach up to the kitchen cabinet with your right hand, and that it feels completely unnatural when you try to reach up with your left hand. This is a result of you repeating certain postures and movements over and over, and your nervous system gradually adapting over time.

Remember, your nervous system is plastic, which means that just as you trained it the first time, you can retrain it. The most effective way to do this with the pandiculation exercises and proprioceptive training that we teach in Clinical Somatic Education.