What is surprising about the cerebellum? This is the department of the brain, which gave us the opportunity to enjoy the beauty and splendor of music, incredible accuracy and grace of dance movements. This is an amazing department of the brain that performs a very meaningful function.

The brain and the nervous system as a whole work with the same discrete signals, short pulses, the amplitude of which is the same. The way to control different organs is to change the number of pulses per unit of time, that is, the frequency of the signal. Also, the degree of influence on the receptor is determined precisely by the change in the pulse frequency.

Our motor system has the potential to very precise actions, to smooth movements or accurate movements of our limbs. To achieve this, muscles that require high flexibility in management have been divided into motor units. The motor unit is a motor neuron and the associated muscle fibers. And the more the motor units are involved in the activity, the greater the force is due to the contraction of the muscle. Also the muscle fibers of different motor units are intertwined for the purpose of load distribution and field of action. Thus, it is possible to control the muscles not only due to the frequency of activation of the motor units, but the total number of them involved in the activity.

Imagine a simple reflex, for which activation of its header leads to a complete contraction of the muscle. In such a reflex, all motor units will be activated almost at the same time. But in the process of vital activity, there may be a need, for example, to smoothly reduce, or plan to relax the muscle, or it requires only a smooth relaxation of the muscle, but then a rapid contraction of the muscle.

In the simulated example, several reflexes lead to a different character of activation of the hypothetical muscle, taking into account that each indicator of action is the motor unit of one muscle. In the example, there is a basic reflex, activation of which leads to the simultaneous launch of all motor units. On the basis of this reflex, reflexes are created that ensure the sequential switching on or off of the motor units, which adds a certain time factor.

In the process of development, the animal learns to control its body, and learning occurs not only in the form of creating associations, linking certain events, but also the ratio of these events in time, and quite accurately. Of course, the propagation of excitation through the reflex arc gives a time factor, but the mechanisms of the formation of reflexes do not allow making this factor sufficiently accurate. In the nervous system, there should be a mechanism that allows you to remember the time intervals between actions, and it is flexible enough for the possibility of retraining.

When developing the theory of brain work and studying the nervous system, I was very surprised by the cerebellum, its features are very different from the rest of the brain structures. First, this is the ratio of the size of the cerebellum and the prescribed functional. The cerebellum occupies approximately 14% of the entire brain (for animals the ratio will be greater) and, as is known, serves to coordinate our body, and also performs some autonomic functions. In this case, the defeat of the cerebellum causes a violation of coordination in the form of the difficulty of maintaining balance, accuracy of movements, uneven handwriting, slow speech, etc. For the success of the animal, these functions are very important, but the size of the cerebellum is larger, for example, than the Wernicke and Broca areas together, although these areas are responsible for human speech, that is, they perform more complex functionality with smaller dimensions.

Secondly, there are unusual neurons in the cerebellum — the Purkinje cells. The dendrites of these cells strongly branch from one side of the cell nucleus, branching in one plane. Such a form of the cell must be something caused, usually the dendrites of neurons grow without strict orientation in the planes.

Third, the structure of the cerebellar cortex differs significantly from the structure of the cortex of the neocortex. In the cerebellar cortex, only three layers are distinguished: the molecular layer, the Purkinje cell layer and the granular layer. If the evolution of the neocortex increased the number of its layers, then this did not happen in the cerebellum. Usually evolution does not touch what works well and sufficiently performs its functional. Given that the cerebellum evolves quite early, we can say that the structure of its cortex is perfectly refined by evolution under its functions.