The reticular formation of the brainstem is a complex of neurons that have extensive connections with different nerve centers, with each other and with the cortex of the hemispheres. It runs in the rostral direction to the thalamus. Consider further its features.
Reticular formation functions
The tasks of the complex include the processing of sensory information. In addition, the reticular formation provides an activating effect on the cortex, exercising control of the activity of the spinal cord. Due to this, the skeletal muscle tone, the work of the human autonomic and reproductive systems are regulated.
Mechanism of action
It was first identified by R. Granite. The scientist found that the reticular formation can affect the activity of γ-motoneurons. As a result, γ-efferents (their axons) provoke a reduction in muscle spindles and, accordingly, an increase in afferent impulses of muscle receptors. The signals entering the spinal cord provoke excitation of α-motoneurons. This causes muscle tone. It was found that the neurons of the formation of the bridge and the medulla are involved in the implementation of this function. Their behavior is diametrically opposite. The latter provoke the activation of α-motoneurons in the flexor muscles and, accordingly, inhibit them in the extensors. Neurons of the bridge are the opposite. The reticular formation is associated with the cerebellum and the cortex, from which information comes. This allows us to conclude that it acts as a collector of non-specific sensory flow, which may be involved in the regulation of muscle activity. However, at present, the need for a formation duplicating the tasks of neurons 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 formations. In particular, we can distinguish the centers:
- Respiratory and vasomotor. They are located in the medulla oblongata.
- Coordination gaze. It is in the midbrain.
- Hunger, saturation and thermoregulation. They are located in the intermediate brain.
The reticulospinal band acts as a key tract. It passes to the neurons in the motor nuclei of the anterior spinal horns and cranial nerves along the trunk and to the intercalated elements of the autonomic nervous system. From them lie the thalamo-cortical fibers. They provide activation of the cortex, which is necessary for the perception of specific stimuli. These thalamo-cortical fibers end 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 parts, as well as the whole brain as a whole, will not be able to carry out all their diverse complex tasks. The neuron complex is directly involved in the process of regulating sleep and wakefulness. The results of the experiments allowed to explain some of the observations of surgeons. Thus, during operations on the brain, cuts can be made in the cortex of the hemispheres, and some of the tissue can be removed. At the same time, the patient will not lose consciousness. However, if the reticular formation is affected with a scalpel. man will fall into a deep sleep.
Today, the specific nerve channels through which information is transmitted from the sense organs to the brain are well studied. This is how the crust 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 branches extend from all fibers directed from the periphery to the cortex. They end at the cell surface of the formation. External irritation of any nature has a stimulating effect on it. At this moment, a kind of “energy charging” takes place. Acting as a brain center, the formation determines the degree of working capacity of the cortex. By activating all departments, it provides an accurate synthesis and analysis of the diversity of information that enters the cortex from the outside world.
Reaction to body substances
The reticular formation is sensitive not only to nerve signals, but also to compounds dissolved in blood. In particular, talking about sugar, hormones, carbon dioxide, oxygen. Of particular importance among these substances is adrenaline. With emotional overstrain - with anger, fear, a state of passion, rage - prolonged excitement of the formation is noted. It is supported by adrenaline, vigorously released in the 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 a dream, CO2 begins to accumulate in the blood. Carbon dioxide activates the reticular formation, resulting in 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 the study of its structure and the tasks that it realizes are widely used in psycho-and neuropharmacology. It has been established that lethargy, apathy, drowsiness or irritability, insomnia can be caused by a disorder in the work of the reticular formation. This neural complex also plays a certain role in the process of the emergence of many pathologies of the CNS.