Physiology is a science that gives us an idea of the human body and the processes taking place in it. One of these processes is the inhibition of the CNS. It is a process that is generated by excitation and is expressed in the prevention of the appearance of another excitation. This contributes to the normal functioning of all organs and protects the nervous system from overexcitation. Today, there are many types of inhibition that play an important role in the functioning of the body. Among them, reciprocal inhibition (combined) is also distinguished, which is formed in certain inhibitory cells.
Types of central primary braking
Primary inhibition is observed in certain cells. They are found near inhibitory neurons that produce neurotransmitters. In the CNS, there are such types of primary inhibition: recurrent, reciprocal, lateral inhibition. Let's see how each works:
- Lateral inhibition is characterized by the inhibition of neurons by the inhibitory cell that is located near them. Often this process is observed between such neuronsretinas of the eyes, both bipolar and ganglionic. This helps create conditions for clear vision.
- Reciprocal - characterized by a mutual reaction, when some nerve cells produce inhibition of others through the intercalary neuron.
- Reverse - is caused by inhibition of the neuron of the cell, which inhibits the same neuron.
- Return relief is characterized by a decrease in the reaction of other inhibitory cells, in which the destruction of this process is observed.
In simple neurons of the central nervous system, after excitation, inhibition occurs, traces of hyperpolarization appear. Thus, reciprocal and recurrent inhibition in the spinal cord occurs due to the inclusion of a special inhibitory neuron in the spinal reflex circuit, which is called the Renshaw cell.
Description
In the central nervous system, two processes are constantly working - inhibition and excitation. Inhibition is aimed at stopping or weakening certain activities in the body. It is formed when two excitations meet - inhibitory and inhibitory. Reciprocal inhibition is one in which the excitation of some nerve cells inhibits other cells through an intermediate neuron, which has a connection only with other neurons.
Experimental discovery
Reciprocal inhibition and excitation in the CNS were identified and studied by Vedensky N. E. He did an experiment on a frog. Excitation was carried out on the skin of her hind limb, which caused bending and straighteninglimbs. Thus, the coherence of these two mechanisms is a common feature of the entire nervous system and is observed in the brain and spinal cord. It was found in the course of experiments that the performance of each action of movement is based on the relationship of inhibition and excitation on the same nerve cells of the central nervous system. Vvedensky N. V. said that when excitation occurs at any point of the central nervous system, induction appears around this focus.
Combined inhibition according to Ch. Sherrington
Sherrington C. argues that the value of reciprocal inhibition is to ensure complete coordination of limbs and muscles. This process allows the limbs to bend and straighten. When a person reduces a limb, excitation is formed in the knee, which passes into the spinal cord to the center of the flexor muscles. At the same time, a deceleration reaction appears in the center of the extensor muscles. This happens and vice versa. This phenomenon is triggered during motor acts of great complexity (jump, run, walk). When a person walks, he alternately bends and straightens his legs. When the right leg is bent, excitation appears in the center of the joint, and the process of inhibition occurs in a different direction. The more complex the motor acts, the greater the number of neurons that are responsible for certain muscle groups are in reciprocal relationships. Thus, the reciprocal inhibition reflex arises due to the work of the intercalary neurons of the spinal cord, which are responsible for the process of inhibition. coordinatedrelationships between neurons are not constant. The variability of the relationship between the motor centers enables a person to make difficult movements, for example, to play musical instruments, dance, and so on.
Reciprocal inhibition scheme
If we consider this mechanism schematically, then it has the following form: the stimulus that comes from the afferent part through the usual (intercalary) neuron causes excitation in the nerve cell. The nerve cell sets the flexor muscles in motion, and through the Renshaw cell, it inhibits the neuron, which causes the extensor muscles to move. This is how the coordinated movement of the limb proceeds.
Extension of the limb is the other way around. Thus, reciprocal inhibition ensures the formation of reciprocal relationships between the nerve centers of certain muscles thanks to Renshaw cells. Such inhibition is physiologically practical as it makes it easy to move the knee without any auxiliary control (voluntary or involuntary). If this mechanism did not exist, then there would be a mechanical struggle of human muscles, convulsions, and not coordinated acts of movement.
The essence of combined inhibition
Reciprocal inhibition allows the body to make voluntary movements of the limbs: both easy and quite complex. The essence of this mechanism lies in the fact that the nerve centers of the opposite action are simultaneously in the opposite state. For example, when the inspiratory center is stimulated, the expiratory center is inhibited. If the vasoconstrictor center is in an excited state, then the vasodilating center is in a inhibited state at this time. Thus, the conjugated inhibition of the centers of reflexes of the opposite action ensures the coordination of movements and is carried out with the help of special inhibitory nerve cells. A coordinated flexion reflex occurs.
Volpe braking
Volpe in 1950 formulated the assumption that anxiety is a stereotype of behavior, which is fixed as a result of reactions to situations that cause it. The connection between stimulus and response can be weakened by a factor that inhibits anxiety, such as muscle relaxation. Wolpe called this process the "principle of reciprocal inhibition". It underlies today the method of behavioral psychotherapy - systematic desensitization. During it, the patient is introduced into many imagined situations, while muscle relaxation is caused with the help of tranquilizers or hypnosis, which reduces the level of anxiety. As the absence of anxiety becomes fixed in mild situations, the patient moves on to difficult situations. As a result of therapy, a person acquires the skills to independently control disturbing situations in reality using the technique of muscle relaxation, which he has mastered.
Thus, reciprocal inhibition was discovered by Wolpe and is widely used today in psychotherapy. The essence of the method lies in the fact that there is a decrease in the strength of a certain reaction under the influence of another,which was called at the same time. This principle is at the heart of cont-conditioning. Combined inhibition is due to the fact that the reaction of fear or anxiety is inhibited by an emotional reaction that occurs simultaneously and is incompatible with fear. If such inhibition occurs periodically, then the conditional connection between the situation and the anxiety reaction weakens.
Volpe method of psychotherapy
Joseph Wolpe pointed out that habits tend to fade when new habits develop in the same situation. He used the term "reciprocal inhibition" to describe situations where the appearance of new reactions leads to the extinction of previously occurring reactions. So, with the simultaneous presence of stimuli for the appearance of incompatible reactions, the development of a dominant reaction in a certain situation presupposes a conjugated inhibition of others. Based on this, he developed a method for treating anxiety and fears in people. This method involves finding those reactions that are suitable for the occurrence of reciprocal inhibition of fear reactions.
Volpe singled out the following reactions that are incompatible with anxiety, the use of which will make it possible to change a person’s behavior: assertive, sexual, relaxation and “anxiety relief”, as well as respiratory, motor, drug-enhanced reactions and those caused by conversation. Based on all this, various techniques and techniques have been developed in psychotherapy in the treatment of anxious patients.
Results
Thus, today scientists have explained the reflex mechanism that uses reciprocal inhibition. According to this mechanism, nerve cells excite inhibitory neurons that are located in the spinal cord. All this contributes to the coordinated movement of the limbs in humans. A person has the ability to perform various complex motor acts.
