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 central nervous system. It is a process that is generated by excitation and is expressed in preventing the appearance of another excitation. This helps to ensure 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 body. Reciprocal inhibition is also among them. (combined), which is formed in certain brake cells.
Types of central primary braking
Primary inhibition is observed in certain cells. They are located near the inhibitory neurons that are produced by neurotransmitters. In the central nervous system, there are such types of primary inhibition: return, reciprocal, lateral inhibition. Let's see how each of them works:
- Lateral inhibition is characterized by the inhibition of neurons by the brake cell that is located near them. Often this process is observed between retinal neurons such as bipolar and ganglionic. This helps to create the conditions for a clear vision.
- Reciprocal - characterized by a mutual reaction when some nerve cells inhibit others through an intercalated neuron.
- The return - is caused by inhibition of a cell neuron, 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, a slowdown occurs after excitation, traces of hyperpolarization appear. Thus, reciprocal and reverse inhibition in the spinal cord occurs due to the inclusion in the chain of the spinal reflex of a special inhibitory neuron, which is called a Renshaw cell.
Description
In the central nervous system, two processes are constantly working - inhibition and excitement. Inhibition in this case is aimed at stopping or weakening a certain activity 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 central nervous system were identified and studied by Vedensky N.E. He conducted an experiment on a frog. Excitation was carried out on the skin of her hind limb, which caused bending and straightening of the limb. Thus, the consistency 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 during experiments that the execution of each action of the movement is based on the relationship of inhibition and excitation on the same CNS nerve cells. Vvedensky N.V. spoke of the fact that when excitation occurs at any point in the central nervous system, induction appears around this focus.
Combined braking according to C. Sherrington
Sherrington Ch. Argues that the importance of reciprocal inhibition is to ensure complete coordination of the limbs and muscles. This process allows the limbs to bend and straighten. When a person reduces a limb, excitement forms 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 by motor acts of great difficulty (jump, run, walking). When a person walks, he alternately bends and straightens his legs. When the right leg is bent, excitement appears in the center of the joint, and 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 inserted neurons of the spinal cord, which are responsible for the inhibition process. The coordinated relationship of neurons is variable. The variability of the relationship between the motor centers allows a person to make difficult movements, for example, play musical instruments, dance and so on.
Reciprocal braking: scheme
If we consider this mechanism schematically, it has the following form: the stimulus, which comes from the afferent part through a normal (insertion) neuron, causes excitation in the nerve cell. The nerve cell drives the flexor muscles, 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 opposite. So, reciprocal inhibition ensures the formation of reciprocal relationships between the centers of the nerves of certain muscles thanks to Renshaw cells. Such inhibition is practical from the point of view of physiology, since it makes easy the movement of the knee without any auxiliary control (voluntary or involuntary). If this mechanism did not exist, then a mechanical struggle of the muscles of the person, convulsions, rather than coordinated acts of movement, would appear.
The essence of combined braking
Reciprocal inhibition allows the body to make voluntary movements of the limbs: both light and fairly complex. The essence of this mechanism is that the nerve centers of the opposite action are simultaneously in the opposite state. For example, when the center of inspiration is excited, the center of exhalation is inhibited. If the vasoconstrictor center is in an excited state, then the vasodilator is at this time inhibited. Thus, the conjugate inhibition of centers of reflexes of the opposite action provides coordination of movements and is carried out using special inhibitory nerve cells. A consistent flexion reflex occurs.
Volpe braking
In 1950, Volpe formulated the assumption that anxiety is a stereotype of behavior that is anchored as a result of reactions to situations that cause it. The connection between the stimulus and the reaction can be weakened if a factor acts that inhibits anxiety, such as muscle relaxation. Volpe called this process "the principle of reciprocal inhibition ." Today it underlies the method of behavioral psychotherapy - systematic desensitization. In its course, the patient is introduced into many imaginable situations, at the same time muscle relaxation is caused by tranquilizers or hypnosis, which reduces anxiety. As the absence of anxiety is consolidated in mild situations, the patient proceeds to difficult situations. As a result of therapy, a person acquires the skills to independently control alarming situations in reality using the muscle relaxation technique that he has mastered.
Thus, reciprocal inhibition was discovered by Volpe and is widely used today in psychotherapy. The essence of the method is that there is a decrease in the strength of a certain reaction under the influence of another, which was caused simultaneously. This principle is at the heart of contra-conditioning. Combined inhibition is caused by 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 relationship between the situation and the alarm response weakens.
Method of psychotherapy Volpe
Joseph Volpe drew attention to the fact that habits tend to fade away if 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 incentives for the appearance of incompatible reactions, the development of a dominant reaction in a certain situation involves the associated 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 identified the following reactions, which are incompatible with anxiety, the use of which will make it possible to change a person’s behavior: assertive, sexual, relaxation and “anxiety relief” reactions, as well as respiratory, motor, and drug-induced reactions and those caused by conversation. Based on all this, various techniques and techniques in psychotherapy have been developed in the treatment of anxious patients.
Summary
Thus, to date, scientists have explained the reflex mechanism, which uses reciprocal inhibition. According to this mechanism, nerve cells excite inhibitory neurons that are located in the spinal cord. This all contributes to the coordinated movement of limbs in humans. A person has the ability to perform various complex motor acts.