Motor function in the brain
Our brain is one of the many marvels of the natural world, with the way it works seems to become more complicated with every study done into it. One of the things that makes me wonder the most is how our brain performs the movement. Motor function is one of the most important functions that we have, allowing us to independently fulfil most if not all of our other physical needs. The brain is complicated as it is without having to bring the rest of the body into it. It works in conjunction with so many other internal organs to just keep us alive. So how does it work to make us move?
Well, motor systems are mainly controlled in the frontal lobes of the brain, with each section of the primary motor cortex coinciding with a different body part with which it has control. The first stage of the movement is the thought or intent of moving. Unless the action is a reflex action, it is the premotor areas that are responsible for planning and coordinating the movement within your body. One interesting thing about motor functions is that they are contralateral, meaning that it is the opposite side of the brain that controls the functions as it is cross-wired. For example, the left arm and leg are controlled by the right brain while the right arm and leg are controlled by the left. The map of the body within the brain, as in where the body is controlled from, is called the homunculus, the size of which is determined by the level of fine motor function controlled by those specific parts of the body. One example of this is the fingers and thumb, which have a larger area as they are often used to manipulate objects and are therefore in need of fine motor functions.
The connections to the muscles within the body and the primary motor cortex are so important that any damage done to this will lead to physical impairment. For example, people who suffer strokes that cause damage to the primary motor cortex are actually bound to develop an impaired ability to move a part or parts of their body on the opposite side to the damaged primary motor cortex. If the damage is specific to only one part of the homunculus, then it will only be that part of the body on the opposite side that will be unable to be moved. This impairment may not be permanent, however, because of the brain’s tendency to plasticity, wherein which it can possibly adapt to damage that is done to it. Really it is all about the repetition of an activity. The more an activity is done, the stronger the neural shortcuts will be for that movement, which will, in the future, make it easier for that movement to be performed.
Our brain is a wonderful thing and I sometimes think about where it started. Was it always so developed? Did it always have all of these amazing capabilities? I am grateful to know that my brain is ready to continue on, even after damage.