The cerebellum is the central nervous system organ located in the lower back of the brain. It can be compared to a smaller version of the brain in size and structure. Just like the brain, it consists of two hemispheres (hemispheres). Although it makes up one-tenth of the brain by weight, about half of the neurons in the brain originate in the cerebellum.
Functions of the Cerebellum
The most important function of the cerebellum is the regulation of movements. When we make a voluntary movement, the first signal occurs in the motor cortex in our brain. The signals go to the cerebellum before reaching the muscles. The cerebellum receives information about planned movements from the cerebral cortex. Information about the position of the body reaches the cerebellum via the spinal cord. By using this information, it ensures that the movement is fluent and that the balance is maintained.
For example, let’s say we want to reach for a glass on the table while standing. The cup-reaching plan is formed in the motor cortex. But for this plan to result in fluid motion, a few things must happen. First, the movement should be performed according to the current position of our body. The movements required are different when loaded on one foot compared to standing on two legs. In addition, the muscles that oppose the movement should be prevented. For example, while the muscles that extend the arm are working, the muscles that provide the bending of the arm should be able to relax. Therefore, it is important that the cerebellum integrates the action plan it receives from the motor cortex with information about the current state of the body and muscles.
Many minor adjustments are required in the movement along the way while reaching for the glass. From the outside, our movements seem to consist of a few large components such as reaching and holding, but there are much smaller components in our brain. The plan of each component changes according to the results from the previous motion component. In other words, while we extend our hand to the glass, our brain receives real-time information about the position of our hands and arms and makes changes according to this information during movement. These changes happen unconsciously, within milliseconds. The cerebellum makes these small but constant adjustments to movement. When the cerebellum detects deviations from the original movement plan, it sends the necessary plan to correct them to the motor cortex, and this information acts on the next component of movement.
Cerebellum damage may occur due to stroke , brain hemorrhage, trauma, tumor, infection, genetic abnormalities.
The error detection and correction mechanism of the cerebellum plays an important role in making our movements precise, smooth and coordinated. These features are more noticeable in the movements of a person with cerebellum damage. Cerebellum damage does not cause paralysis, but it can cause loss of balance, slowing of movements and coarsening. Muscle coordination disorder causes ataxia. In cerebellar ataxia, problems are seen not in the initiation of movement, but in its execution. The timing of the movements is distorted, trembling and jumping movements are seen. The cerebellum also plays a role in the control of eye movements. It provides the fluency of speech, speech difficulties can be seen in cerebellum damage.
The cerebellum is also important in learning new movement patterns. The first time we try something like riding a bike or driving, we act clumsily. As you practice and learn, the movements become fluid and automatic. This learning process is associated with the strengthening of synapses in the cerebellum.
Cognitive and emotional disorders can also be seen in the cerebellum damage. This shows that the cerebellum also has functions other than the coordination of movement.