We explain how this brain region works and what diseases can affect it.
The human cerebellum is one of the most important parts of the brain, and constitutes one of the structures of the Central Nervous System with the highest concentration of neurons.
In the human body, this structure is located under the occipital lobes and the fourth ventricle and behind the brain stem, and has a close relationship ofneuronal interconnectionswith the latter region of the nervous system.
Throughout this article we will see what are the characteristics of the human cerebellum, its main parts, and its functions in the organism.
- Recommended article:”Human brain: its main parts and functions”
What is the cerebellum?
As we have seen before, the cerebellum is a part of the brain; Specifically, it is formed from the rhombencephalon during the development of embryos, like the brain stem, and is present in the anatomy of all vertebrate animals.
As with the cerebral cortex, the cerebellum has a series of cracks and folds (although they follow a different pattern, of finer shapes) and is divided into two separate halves, two hemispheres located to the left and right.
Functions of this region of the brain
One of the most studied functions of the cerebellum is the coordination of movements, both voluntary and spontaneous and automated. This is something that can be intuited in neurological alterations that affect this structure, as in ataxias, in which the person is unable to carry out well-coordinated chains of movements, such as walking, writing or dressing.
In addition, it has been seen that interferences with the functioning of the cerebellum often cause problems maintaining balance, something that is not surprising considering that to keep us standing it is necessary to coordinate many groups of muscle fibers.
On the other hand, it has been observed that humans and in great apes in general (gorillas, chimpanzees, orangutans, etc.) the cerebellum is much larger in relation to other parts of the nervous system than in other primate species. This fact raises suspicions about the involvement of the cerebellum in cognitive functions.
It is likely that much of these cognitive functions are forms of motor learning, that is, the ability to learn movements. In addition, it has been seen that the cerebellum is involved in the phenomenon of psychological conditioning.
All this fits with a fact that has been observed when studying the microscopic composition of this part of the brain: it stands out for its neuronal plasticity, that is, its ability to modify its connection patterns between the neurons that form it, depending on the demands of the environment and the tasks that need to be performed in it to adapt to its demands.
In any case, it seems unlikely that a brain structure with theneuronal densityof the cerebellum is involved only in the coordination of movements.
Possibly, it works in coordination with many other areas of the brain, so that although it does not specialize in a very specific function, it takes part in many kinds of mental processes: memory, learning, programming of chains of movements by activation of muscles, etc.
Connections with other nerve structures
Despite being located at one end of the brain, this structure is connected to all sensory pathways and all motor pathways, that is, all input and output circuits that bring information from the senses and send orders to the muscles, respectively.
Parts of the cerebellum
There are many ways to classify parts of the cerebellum; Here we will see several of the main ones focused on its anatomical structureat the macroscopic level, observable with the naked eye.
1. Anterior, posterior and floculonodular lobe
These three lobes are distributed more or less according to their proximity to the anterior part of the cerebellum, its area closest to the face. That is, according to its horizontal distribution.
2. Hemispheres and vermis
If we look at the cerebellum according to its vertical distribution, we can find the two cerebellar hemispheres, symmetrical with each other, and the vermes between them.
3. Layers of the cerebellar cortex
According to their degree of depth (i.e. proximity or distance to the contour of the brain) we can distinguish between the granular layer, the layer of Purkinje cells, and the molecular layer. All of them get their name from the microscopic bodies that compose them.
4. Peduncles of the cerebellum
The cerebellum has six important bridges of fixation and connection with the rest of the areas of the brain: these are the peduncles, distributed in pairs. These sets of neuronal axons go deep into the brain stem.
Diseases that affect this structure
There are many diseases capable of damaging the cerebellumand interfering with the processes it carries out. The most important, either because of their frequency of appearance or their ability to destroy parts of the cerebellum, are the following.
1. Dandy-Walker syndrome
This syndrome causes the vermis of the cerebellum to not form well, and causes seizures, vision problems, and low muscle tone.
2. Cerebellar syndrome
This set of symptoms damages the cerebellum and generates phenomena such as ataxia, hypotonia, nystagmus, dysarthria, and unintentional tremors. In the case of ataxia, it is a sign that affects the capacity for voluntary and involuntary movement.
3. Cerebelitis
Inflammation of the cerebellum often causes symptoms such as dysmetria and trouble moving. It usually occurs together with other alterations in the human body, since the problems that cause this condition are usually serious and damage structures of vital importance for the maintenance of the organism.
4. Head injuries
The cerebellum can be damaged by blows received in the back of the head, which can cause death if large areas of this organ are damaged or medical intervention is not timely.
References
- Clarke, E., O’Malley, C.D. (1996). Cerebellum. The Human Brain and Spinal Cord. Oxford: Norman Publishing.
- Fine, E.J., Ionita, C.C., Lohr, L. (2002). The history of the development of the cerebellar examination. Semin Neurol 22 (4): 375 – 384.
- Gao, W.O., Heintz, N., Hatten, M.E. (1991). Cerebellar granule cell neurogenesis is regulated by cell-cell interactions in vitro. Neuron. 6(5):705 – 715.
- MacLeod, C.E., Zilles, K., Schleicher, A., Rilling, J.K., Gibson, K.R. (2003). Expansion of the neocerebellum in Hominoidea. Journal of Human Evolution. 44 (4): 401 – 429.
- Roberts, P.D., Portfors, C.V. (2008). Design principles of sensory processing in cerebellum-like structures. Early stage processing of electrosensory and auditory objects. Biological Cybernetics. 98 (6): 491 – 507.
- Shi, Z., Zhang, Y., Meek, J., Qiao, J., Han, V.Z. (2008). The neuronal organization of a unique cerebellar specialization: the valvula cerebelli of a mormyrid fish. Journal of Comparative Neurology. 509 (5): 449 – 473.
To the classic question “what do you do?” I always answer “basically I am a psychologist”. In fact, my academic training has revolved around the psychology of development, education and community, a field of study influenced my volunteer activities, as well as my first work experiences in personal services.