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Sensorimotor Amnesia and Muscle Memory

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.

Some people consciously choose to work with their muscle memory, actively training and retraining their muscular patterns in pursuit of a goal. But most of us are unaware that that we are engaged in a constant process of subconsciously reinforcing old movement patterns and learning new ones.

This automatic learning process is innate in all of us, and it serves an important evolutionary purpose. You can imagine how critical muscle memory was to our survival hundreds of thousands of years ago. Back then, only the fit survived, and the ability to move quickly and automatically under stress often meant the difference between life and death.

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.

For example, if we sit slouched forward at our computer day after day, our nervous system learns to keep us in that slouched posture by keeping certain muscles contracted, and our proprioceptive and vestibular systems allow us to get more and more comfortable in this unnatural position. Slouching forward begins to feel normal and even good, and sitting up straight takes effort and feels uncomfortable. We typically remain blissfully unaware of this subconscious adaptation until, one day, it finally causes us pain.

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.