What is brain plasticity?
Brain plasticity is an important characteristic of our brains.
Plasticity refers to the extent to which something can be changed or reformed. Brain plasticity is the ability of our nervous system to change its structure and function in response to new information.
Functional vs structural plasticity
Functional plasticity is when the brain moves a mapped function from a damaged area to an undamaged area. Structural plasticity refers to the brain’s ability to change its physical structure as a result of learning something new, for example learing how to play the piano or learning how roll over or sit.
How does the brain change?
The human brain is made up of about 100 billion brain cells (neurons). Recent research has repeatedly shown that the brain contains the remarkable ability to reorganize pathways, to make new connections.
Use it or loose it
Brain plasticity is a physical process and the gray matter of our brains can actually shrink or thicken; neural connections can be made and refined or weakened and broken.
Changes in the physical brain reveal themselves as a change in our skills. New ‘wires’ (neural pathways) are created that communicate to the body how for example a song should be played on a piano. On the other hand, when we forget or do not do things, this process is reversed. The neuroconnections that made this skill possible will gradually disappear. If you do not do something you will become less skilled at it.
Neuroplasticity and brain injury
A positive side effect of neuroplasticity is that brain activity that is associated with brain function can be moved to a different location of the brain, either as a result of a normal event or in case of recovery after a brain injury. The term for this event is called ‘functional movement’. Dr. Norman Doidge gives a complete explanation and description of functional movements in his book “The Brain That Changes Itself: Stories of Personal Triumph from the Frontiers of Brain Science”. In his follow-up book ‘The brains way of Healing’ he also describes the work of Anat Baniel.
A special example is that of a surgeon in the 50’s who had a stroke, resulting in a paralyzed left arm. During the rehabilitation his working arm was tied so that he could not use it and he was instructed to clean a table. In the first instance, the assignment was daunting and impossible. Slowly but surely, the paralyzed arm began to ‘remember’ how it should move. The surgeon has learned to write again, tennis and many other things that seemed impossible before. This example shows that the functions of the areas of the brain that were killed in the stroke were transferred to healthy areas of the brain.
A study by Maguire, Woollett and Spiers from 2006 showed that Londern taxi drivers have a larger hippocampus (the rear area of the brain) than London bus drivers. This is due to the fact that this area specializes in the acquisition and use of complex spatial information in order to navigate as efficiently as possible. London taxi drivers are required to complete a several-years long training in which they acquire detailed knowledge of Londons roads. Bus drivers use the hippocampus to a lesser extent, as there are fixed bus routes.
What is spasticity?
Spasticity is caused by the removal of inhibitory influences exerted by the cortex.
In our nervous system only two forces are necessary; excitation and inhibition. The balance between neural excitation and neural inhibition is crucial to healthy movement, cognition and behaviour. Our higher brain functions (cortex) is occupied with inhibition, it overrides our spinal cord activity. If part of the brain is damaged, an abnormal increase of the spinal cord reflex is gained due to loss of descending inhibition by the higher cortex, resulting in spasticity.
Stretching to prevent or elevate spasticity or to make muscles longer never works!
A muscle has an automatic stretch reflex to protect the muscle against tearing. If there is too much tension around a muscle, it will contract automatically. That is why stretching a tight muscle is also very painful. Only by tightening the opposite muscle (antagonist) does a muscle release. This can be done by the oppsite of stretching; moving with the contraction instead of going against it.
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