Years ago I had read a story on the internet which intrigued me to no end. I was never sure if the story was real or not. I can’t find it anywhere now, so either my google-fu is weak or it was just some kind of urban legend that kind of faded. The story was about a man who was a professional violin player that for some reason went to prison for a few years. Even though he was not able to bring his violin with him, he found a way to make sure that his time in prison would not cause him to lose his playing abilities. He spent an hour a day simply imagining that he was playing the violin.
Hearing the music in his mind, picturing himself stabling and fingering the instrument with one hand, bowing it with the other. As the story goes, he managed to maintain his level of playing throughout his imprisonment. On the day he left prison, he went back to his hometown, played a concert and performed just as well as he ever did.
Playing the violin takes a lot of brainwork, obviously. Knowing all the theory and knowing the instrument as well as a professional musician does require a lot of practice for the brains. But the interesting part of the story is the fact that his technique has been kept up to notch. Practicing technique requires hours of repetitive playing, and not necessarily anything that is musically interesting. It takes playing up and down musical scales, improving your fingering and grip of the instrument and perfecting every little aspect of it to attain professional technique. There are many methods to practice instruments when access to them is limited but after not having access to a violin for years, you should not be able to play a concert straight away.
This story may easily turn out to be embellished or simply fiction, but it’s a good segway to an interesting and relatively recent field of study. For the past few years, scientists have been testing to see if using mental imagery, like the violin player did, can be used to as a replacement to physical activities. How big a role does the brain have in maintaining technical skills? The idea of improving using only mental imagery seems impossible to me, but slowing down decrement of motor skills if you can’t perform them sounded somewhat plausible to me.
When you think about it, it makes a lot of sense. We usually perceive strength and force generation to be attributed to the muscles. The roles of the motor centers and other centers of our brains are usually considered to be of skill acquisition and movement coordination. But the muscles are controlled by our brains - every muscle fiber is innervated by our nervous system. The order that makes muscles flex or relax comes from the brain, through the nervous system, and to the muscle fibers. We are used to think of the brain as the order-giver and the muscles as the executioner of orders. But what if the role of the brain is more than just give the order? What if the state and health of the brain has an impact on the abilities of the muscles?
Mental imagery has been well studied by psychologists, and now its usefulness is being tested in other fields. In 2014, a paper called ‘The power of the mind: the cortex as a critical determinant of muscle strength/weakness’ by Brian C. Clark and his colleagues was published. The paper details a study in which they are testing the effect of mental imagery on muscle weakening. To quantify that, they compared three groups of participants. The first group had their wrist immobilized for a month, preventing any use of the hand. The second group was also immobilized for a month, but they did mental imagery exercises. Five times a week, this group had imagined using the wrist muscles, under close supervision to make sure that they’re not actually activating them. The third group was a control group, they were not immobilized. Measurements of wrist strength were taken before, at the end, and a week after the immobilization period.
The results, in short, show that the muscle strength of the group that was immobilized decreased by about 50%, while the muscle strength of the group that was immobilized and underwent mental imagery exercises decreased by only about 24%. The control group showed no muscle weakening. Two other factors that were tested - voluntary activation and cortical silent period - have also shown improvement for the group that has done mental imagery relative to the group that was immobilized without mental imagery.
This is all very preliminary and in this field there are still a lot of questions we have not even thought about asking, but the results of Clark’s study suggest a connection between mental imagery and muscle weakness attenuation that is worth studying. These results point at a stronger connection between neurological factors and muscle weakening - at least weakening that is a result of disuse. This might lead to potential strategies that can be used to slow down muscle weakness. Patients who are restricted to a bed for a period of time can undergo mental imagery treatment to prevent weakening of muscles due to disuse. These methods could shorten the recovery period for people with broken limbs as they may ease the physiotherapy treatment. People with physical disabilities may use this technique to ‘exercise’ muscles that they otherwise can’t, thus contributing to general health. Even today there are athletes that use mental imagery techniques as part of their training regime. Mental imagery training might not be the difference between a middling and an outstanding athlete, but it may improve the connection between the nervous system and the muscles and push an athlete a bit further.
Let’s now take a step back. Clark’s study shows that around 50% of force generation is affected by the nervous system, and that it’s not just muscle work at play. The study establishes a connection between the nervous system and the muscles that goes a little deeper than we thought. That means that detecting muscle weakness in seemingly healthy people might be due to irregularities in the brain - mainly in the motor regions, maybe in other areas as well. Some scientists have wondered - could we use this to assess or diagnose medical cases?
A study that was released in the past few months by Joseph Firth et. al. may point in that direction. The paper is called ‘Grip Strength Is Associated With Cognitive Performance in Schizophrenia and the General Population: A UK Biobank Study of 476,559 Participants’. Basically, they have used data collected from nearly half a million healthy individuals and 1,162 individuals with schizophrenia to test for relationships between grip strength and a few cognitive domains, such as visual memory and reaction time. Grip strength measurement is a measurement that is easily taken and highly effective in determining muscular function. In the healthy individuals, the data shows a strong and consistent connection between cognitive health and grip strength among all domains tested. Stronger grip strength points at better cognitive performance. In the schizophrenia patients, most of the domains that were tested have shown no discernible difference. In a few specific domains, though, the results were different between the two groups. If we test for more domains and learn the pattern that is correlated with schizophrenia patients, we might be able to use this simple test as an early detection test for schizophrenia and other mental disorders.
The grip strength test may one day be used for detecting and preventing many maladies. For example, we could use it to detect the effects of old age. Grip strength tests could be part of regular checkups people go through as they get older. If we’re already looking for any signs of irregularities, we might as well check grip strength. Early detection of signs of deterioration that are regular with age might let us act quicker and slow down the process.
After showing a connection between various cognitive domains and grip strength, we have in front of us a very interesting question: does this connection work in both ways? We have seen that people who display improved mental abilities also show relatively matching grip strength. We believe that we will be able to assess mental status by testing grip strength. That is due to the fact that the nervous system is playing a role in activating muscles and generating force. But what if putting the muscles to work is, in a way, also exercising the nervous system, and thus helps in keeping it healthy? Does working out activate domains in the brain and helps to maintain them? If so, physical activity, especially as you get older, could be more important than we believe.
It seems that no matter what functions and properties we attribute to the brain and the nervous system, we always find that we underestimate them. It seems obvious, in hindsight, though. The brain is the control center for mostly anything that happens in our body, voluntarily or reflexively. It makes sense that it’s role in many motor functions is more than just giving the order and then overseeing from afar. A concept like mental imagery, imagined workouts, seems a bit like something out of science-fiction. And testing for cognitive health by measuring grip strength is such a shortcut that it might feel a little like cheating. But we may hope that they pan out right and we could one day use them to our benefit.
There are a few additional notes to this article in the blog section.
Thank you for reading!