The reticular formation of the brainstem is a complex of neurons that have extensive connections with different nerve centers, with each other and the cortex of the hemispheres. It lies in the rostral direction to the thalamus. Let us further consider its features.
Functions of the reticular formation
The tasks of the complex include the processing of sensory information. In addition, the reticular formation provides an activating effect on the cortex, monitoring the activity of the spinal cord. Due to this, the tone of skeletal muscles, the work of the vegetative and sexual systems of a person are regulated.
Mechanism of action
It was first discovered by R. Granit. The scientist established that the reticular formation can affect the activity of γ-motoneurons. As a result, γ-efferents (their axons) provoke a reduction in the spindles of the musculature and, correspondingly, an increase in the afferent impulse of the muscle receptors. The signals entering the spinal cord provoke the excitation of α-motoneurons. This also determines the tone of the musculature. It was found that neurons of the formation of the bridge and medulla oblongata participate in the realization of this function. Their behavior is diametrically opposed. The latter provoke the activation of α-motoneurons in flexor muscles and, accordingly, inhibit them in the extensors. Neurons of the bridge act on the contrary. The reticular formation is connected with the cerebellum and bark, from which the information comes. This allows us to conclude that it acts as a collector of the nonspecific sensory flow, which, possibly, participates in the regulation of muscular activity. However, the need for a formation duplicating neuronal tasks in the red and vestibular nuclei has not yet been clarified.
The reticular formation is formed by scattered cells. Some of them are considered vital entities. In particular, it is possible to single out the centers:
- Respiratory and vasomotor. They are located in the medulla oblongata.
- Coordination of the gaze. It is in the middle brain.
- Hunger, saturation and thermoregulation. They are located in the diencephalon.
As a key tract acts reticulospinal. It passes to the neurons in the motor nuclei of the anterior spinal horns and cranial nerves along the trunk and to the intercalary elements of the nervous vegetative system. They are thalamo-cortical fibers. They provide the activation of the cortex, which is necessary for the perception of specific stimuli. These thalamo-cortical fibers terminate in all cortical layers.
In the course of the research it was revealed that the reticular formation has an activating effect on the cortex. This neural complex acts as a kind of "energy center". Without it, the nerve cells of the cortex, its various departments, and the whole brain as a whole, will not be able to perform all of their diverse and complex tasks. The neuron complex is directly involved in the process of regulating sleep and wakefulness. The results of the experiments made it possible to explain some observations of surgeons. Thus, in the process of operations on the brain, cuts can be made in the cortex of the hemispheres, a part of the tissue is removed. The patient will not lose consciousness. However, if the scalpel will be affected by the reticular formation. a person falls into a deep sleep.
Today, specific nerve channels have been studied quite well, in which information from the sense organs is transmitted to the brain. This is how the bark learns about the nature of the stimulus acting on the body. In accordance with this, it sends different impulses to systems and organs. Studies have shown that from all fibers directed from the periphery to the cortex, branches branch out. They end on the surface of the cells of the formation. External irritation of any kind has an exciting effect on it. At this point, there is a kind of "charging energy." Acting as a think tank, the formation determines the degree of efficiency of the cortex. By activating all departments, it provides an accurate synthesis and analysis of the variety of information that enters the cortex from the outside world.
Reaction to substances of the body
The reticular formation is sensitive not only to nervous signals, but also to compounds dissolved in the blood. In particular, we are talking about sugar, hormones, carbon dioxide, oxygen. Adrenaline is especially important among these substances. With emotional overstrain - with anger, fear, a state of affect, anger - there is a continuous excitation of the formation. It is supported by adrenaline, stricter in blood. The activity of the complex is largely determined by other chemical compounds. First of all, it is carbon dioxide and oxygen. For example, if a person has difficulty breathing in their sleep, then CO2 begins to accumulate in the blood. Carbon dioxide activates the reticular formation, as a result of which a person wakes up.
Clinical studies and experimental data obtained in physiological laboratories showed that the reticular formation is directly related to the occurrence of emotions. The results of studying its structure and the tasks it implements are widely used in psycho- and neuropharmacology. It was found that lethargy, apathy, drowsiness or irritability, insomnia can be caused by a disorder in the work of the reticular formation. This neural complex also performs a certain role in the process of the appearance of many pathologies of the central nervous system.