We aren’t normally aware of most of the sensations generated by our own movements. If our awareness was constantly bombarded with every sensation our muscles generated, it would be very difficult to focus on the world around us with its opportunities and dangers. Our brain functions in such a way that it cancels out the sensations that would otherwise arise from self-generated movements. Because of this, we can’t experience the feeling of tickling ourselves as a surprise.
Our inability to tickle ourselves also gives us insight into how we lose awareness of what our bodies are sensing, when we engage in deeply habituated movements and postures. Consider, every time we make a voluntary motion like reaching for a cup of coffee, the part of the brain that sends the instruction to make the muscles move also sends those signals to the sensory processing part of the brain to anticipate the consequences of that movement. Scientists refer to the signal variously as the ‘Motor Copy’, ‘Corollary Discharge’ or ‘Efference copy’. The copy of the movement signal cancels the sensory signal that would otherwise arise from that movement. This enables us to remain sensitive to unexpected sensory signals from the surrounding world. So, unless something goes wrong with reaching for the coffee –ouch! I burned myself! –the act itself can be unconscious once we initiate the movement and we won’t even feel the effort.
Now, think about driving, another complicated behavior that many of us engage in. It’s not a good idea to focus our attention on the tension in our back muscles that allow us to sit upright or the pressure of our bodies against the seat. Our brains learn to accept that tightness in our backs as normal and suppress the ability to notice that sensation so it doesn’t interfere with our engagement with the world or even other thoughts we may be having. So we get out of the car and our back is still tight and we don’t notice it unless it interferes with other activities and we can’t imagine why we are so stiff and inflexible. We think, “I must be getting old!” Thomas Hanna PhD referred to this learning not to sense tightness in our muscles as sensory motor amnesia (SMA) and it is a normal consequence of learning movement habits.
Let’s go over one of the brain regions involved in this process. The cerebellum looks like a separate structure located at the back of the brain and regulates movement, postural control, and muscle tone. It anticipates the sensory consequences of our actions and predicts sensations when your own movement causes them but not when someone else does. The cerebellum also contributes to learning and refining movements. Learning new movement behaviors often progresses from a period of intense conscious focus and awareness of what our bodies are doing and sensing to one where the actions are efficient, stereotyped, and unresponsive to feedback from the environment. This is useful for our ability to quickly respond to events in the world and multi-task but can have the downside of limiting our ability to easily sense the activity of our muscles during stereotypical habitual activities.
So, if you suffer from chronic headaches, shoulder or lower back pain, etc., you may want to think about activities that you engage in frequently (driving, working at the computer, repetitive movements at work, etc.) that could be tightening your muscles in an unconscious, automatic way. Somatics Movement Therapy techniques can help to reset those automatic postures and movements in your brain that are keeping your muscles tight and in pain. The techniques can bring to consciousness what normally is hidden and with awareness comes the potential for lasting change. As these blog posts continue, we will delve deeper into neurophysiology and the strategies underlying Somatic Movement Therapies.
Blakemore SJ, Wolpert D, Frith C. Why can’t you tickle yourself? Neuroreport. 2000 Aug 3;11(11):R11-6. doi: 10.1097/00001756-200008030-00002. PMID: 10943682.
“Clinical Somatic Education, A New Discipline in the Field of Health Care,” by Thomas Hanna, Ph.D; Somatics Journal, Autumn/Winter 1990-91.
Brooks JX, Cullen KE. Predictive Sensing: The Role of Motor Signals in Sensory Processing. Biol Psychiatry Cogn Neurosci Neuroimaging. 2019 Sep;4(9):842-850. doi: 10.1016/j.bpsc.2019.06.003. Epub 2019 Jun 18. PMID: 31401034; PMCID: PMC6733654.
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