Man, like other living organisms, strives to satisfy his biological needs. To maintain the constancy of the internal environment, he must constantly drink, take food, breathe, etc. Due to this, he grows, develops and gives life to offspring. A person realizes his spiritual and social needs in society. A reflex is a stereotypical reaction of a living organism to a certain influence, which takes place with the participation of the nervous system. Reflexes exist in multicellular living organisms with a nervous system.
To satisfy his needs, a person sets goals for himself. At a certain moment, some one becomes the main one. Under the influence of his feelings, a person thinks, imagines, dreams, that is, an image is first created. This imaginative thinking is characteristic of the human psyche.
Since every person lives among people, he must reckon with the opinions of others. A person cannot exist without communicating with other people. Each person has individual characteristics. Speech plays an important role in their formation.
Higher nervous activity
Higher nervous activity, carried out by the cerebral cortex, ensures the most perfect adaptation of humans and animals to constantly changing environmental conditions, lies at the basis of the higher mental functions of a person, such as thinking, memory, consciousness and learning.
“The Father of Russian Physiology” – I.M. Sechenov wrote the book “Reflexes of the Brain”, where he put forward a theory about the reflex principle, which underlies the activity of higher nervous activity. Higher nervous activity. These ideas were continued and developed by I.P. Pavlov, who experimentally proved that conditioned reflexes underlie higher nervous activity.
While studying the digestive system, you learned about the experience of I.P. Pavlov, with the help of which he studied the mechanism of salivation. After conducting experiments, Pavlov discovered that some of the reflexes are congenital – permanent, and the other – acquired.
With numerous coincidences of the conditioned and the unconditioned stimulus reinforced by them, a conditioned reflex is formed. That is, a conditioned reflex always arises on the basis of an unconditioned reflex with multiple coincidence of the above stimuli.
Conditioned and unconditioned reflexes
Now let’s take a closer look at the differences between conditioned and unconditioned reflexes:
Acquired – congenital
Conditioned reflexes are acquired: they are absent in a newborn, they can arise and fade away during life. Unconditioned reflexes are congenital, inherent in genetics and inherited.
Individual – group
Conditioned reflexes are individual, due to previous experience: a child who sees a lemon for the first time in his life does not salivate, but after drinking it, even the thought of a lemon can cause profuse salivation. Unconditioned reflexes are characteristic of all individuals of the species, without exception.
Nonspecific – specific
Conditioned reflexes arise in response to a nonspecific stimulus, for example, light, if a dog has a conditioned reflex to light.
Volatile – permanent
Conditioned reflexes are acquired as adaptation to specific environmental conditions; when the environment changes, they also change, they can be lost and reappear. Unconditioned reflexes are constant, given from birth and do not fade away throughout life.
With bark – without bark
Conditioned reflexes always arise and are carried out with the participation of the cerebral cortex; unconditioned reflexes can do without its participation.
The mechanism of the formation of a conditioned reflex. The study of conditioned reflexes is closely related to Pavlov and his students. Now we will also conduct an experiment on a dog.
Suppose we need to develop a salivary reflex in an animal in response to the switching on of the light. We will use food as an unconditioned stimulus, and turning on a light bulb as a conditional one.
Formation of a conditioned reflex
This effect is due to the fact that in the dog’s brain there is a temporary connection between the visual center and the food center. As we repeat our manipulation, this temporary connection becomes stronger – a closure and the formation of a conditioned reflex occurs.
Inhibition of reflexes
Inhibition processes are obligatory companions of excitation processes in the nervous system. Sechenov was the first to discover and describe the process of inhibition, who proved that irritation of the nerve centers of the diencephalon inhibits the reflex activity of the spinal cord.
Inhibition in the central nervous system Sechenov’s experience
Pavlov developed the teachings of Sechenov and also studied the processes of inhibition. Moreover, due to inhibition, the conditioned reflex has the most accurate and perfect adaptive character in relation to the environment.
Pavlov described two types of cortical inhibition:
The action of this stimulus causes a weakening or complete disappearance of the current conditioned reflex.
This is an innate inhibition, it does not require development, therefore Pavlov called it unconditional.
Conditioned inhibition occurs in the same area of the cortex where the center of the conditioned reflex is located. Conditioned inhibition develops gradually. Remember how we developed a conditioned reflex in a dog to turn on a light bulb. If we stop giving food, and continue to turn on the light bulb, then gradually the salivation of the dog will fade away – this is the conditional inhibition.
In order for the conditioned reflex to be preserved, it is necessary to reinforce it as often as possible: in our case, light is reinforced by food. If you stop turning on the light before giving the dog food, the conditioned reflex will gradually weaken and disappear. This process is called extinction – the disappearance of the conditioned reflex, but if desired, it can be created again.
Pavlov’s doctrine of the first and second signaling systems
Animals have only the first signaling system. Pavlov viewed it as a set of nervous structures, with the help of which the perception of the surrounding world by the senses takes place. The signals in the first signaling system are smell, color, sound – they cause unconditioned reflexes and serve as the basis for the formation of conditioned reflexes.
Pavlov also proved that animals lack a second signaling system. His experience consisted of placing a monkey on a raft in the middle of a lake. The monkey could climb with a pole on two other rafts. On one of them there was a scoop and a tank of water, on the other raft a fire started. The monkey extinguished the fire, performing complex actions: each time it moved to the raft with a tank of water and scooped water from there, instead of scooping water from the lake, which was much closer. Consequently, animals are incapable of generalization and abstract thinking.
In the process of work and communication, a second signaling system arose in a person, closely related to the emergence of speech. Here, a specific irritant is the words in which a person puts a meaning, any concept.
Words have a generalizing meaning, which served as the basis for the possibility of generalization, abstraction and operating with concepts. Language fixes the results of human activity in words, so you can imagine a monkey even if you can’t see it. Owing to oral and especially written speech, it becomes possible to transfer experience to future generations. For any book, including this textbook, it is also worth saying a special thanks to the second signal system.
Types of temperament
Pavlov identified four types of temperament, depending on the strength, balance and mobility of nervous processes in the cerebral cortex. The choleric person is an easily excitable type, the sanguine person is balanced. Phlegmatic – the processes of excitation and inhibition of weak strength, stubborn and diligent in work. And, finally, the melancholic – the processes of excitation and inhibition are unbalanced and weak – very vulnerable and weak-willed, prone to deep feelings.
Emotions, thinking and memory
Thinking is a set of mental processes aimed at cognizing the surrounding reality and thanks to which a person realizes the essence of phenomena and things – as a result of thinking, concepts are formed. Distinguish between elementary thinking, inherent in all animals, and abstract thinking, inherent only to humans.
Memory is the ability of the nervous system, which consists in the ability to consolidate, preserve and further reproduce the information received. Based on the storage time of information, memory is divided into short-term and long-term.
Any information received by us first falls into short-term memory, only with repeated reproduction this information goes into long-term memory. The following types of memory are distinguished: visual, auditory, motor, tactile, mixed.
Sleep is called a state of depression of consciousness, during which all types of sensitivity decrease. Normally, the duration of sleep in an adult is 7-8 hours, in newborns, the duration of sleep reaches 18-20 hours per day. During sleep, the information received during the day is transferred to long-term memory. In the absence of sleep for more than 1-2 weeks, death is possible.
There are two phases of sleep: slow and fast, which alternate several times in one night. The phase of slow sleep consists in the physiological rest of all body systems: the heart rate and blood pressure, body temperature decrease. Hormones begin to be released more actively, the action of which is associated with tissue restoration.
The REM sleep phase is exactly the phase in which we see dreams. In this interval, the eyeballs are actively moving, breathing can become more frequent, the hands make movements. This phase occurs approximately every 60-80 minutes. Thus, in one night we see many dreams, most of which we forget.
Slow and fast sleep
A dream is a kind of representation of the information received in the form of visual images. I will note an interesting fact that all the people we see in a dream, we have already seen in reality. It could be the face of a casual passer-by that we met a few years ago: such information is hidden deep in the subconscious.
Many of us, including myself, have had the experience of being in a state of altered consciousness – a lucid dream.
Somnambulism is a painful condition in which people perform actions while in a state of sleep. Most often, sleepwalking occurs during a period of incomplete awakening after a deep sleep phase. An attack of sleepwalking can last up to several hours, most often sleepwalking occurs in children.
This condition has been known since ancient times, but its causes are still a mystery. There is also no information whether sudden awakening is harmful to a sleepwalker in a state of sleepwalking or not. Most often, sleepwalkers perform stereotypical actions: getting up, cleaning, walking, after which they go to bed and the next morning they do not remember anything about what happened.
Sometimes the actions of sleepwalkers are dangerous for themselves and those around them. There are cases when lunatics left hundreds of kilometers from their home, after waking up they found themselves in another part of the country completely disoriented.