Conditioned and unconditioned Conditioned and unconditioned regulation of human activityregulation of human activity

Higher and lower activity of nervous Higher and lower activity of nervous system system

The lower nervous activity is directed to regulation of body The lower nervous activity is directed to regulation of body functions and organ systems, unification them to entire functions and organ systems, unification them to entire organism. The lower nervous activity is performed due to organism. The lower nervous activity is performed due to congenital forms of behavior. Tcongenital forms of behavior. Thehe congenital forms are congenital forms are unconditioned reflexes, instincts; biological motivations and unconditioned reflexes, instincts; biological motivations and emotions. emotions.

At the adult person the lower nervous activity usually is not At the adult person the lower nervous activity usually is not arises separately from other forms of behavior. Life training arises separately from other forms of behavior. Life training and purchase of acquiring experience results in and purchase of acquiring experience results in specification and modification of congenital forms of specification and modification of congenital forms of behavior due to the conditioned-reflex mechanism.behavior due to the conditioned-reflex mechanism.

Notion about conditioned reflexes Notion about conditioned reflexes

Conditioned reflexes are individually acquired system of Conditioned reflexes are individually acquired system of adaptive reactions of the person and animals. It arises on adaptive reactions of the person and animals. It arises on the basis of formation in the central nervous system of the basis of formation in the central nervous system of temporary communication between centres, some of which temporary communication between centres, some of which percept new irritant and other control some unconditioned percept new irritant and other control some unconditioned reflex. Thus, new irritant form an environment becomes reflex. Thus, new irritant form an environment becomes conditional irritant. It warns person about approach of the conditional irritant. It warns person about approach of the subsequent kinds of activity and prepares him for future subsequent kinds of activity and prepares him for future kinds of activity (eating, avoidance of danger and another).kinds of activity (eating, avoidance of danger and another).

With the help of the conditioned-reflex mechanism such With the help of the conditioned-reflex mechanism such function of nervous system as purposeful behavior of the function of nervous system as purposeful behavior of the person in an environment and society, the adaptation to person in an environment and society, the adaptation to varied conditions of an environment are carried out. Such varied conditions of an environment are carried out. Such activity of nervous system concerns to the higher nervous activity of nervous system concerns to the higher nervous activity.activity.

The mechanism of formation of conditioned reflexesThe mechanism of formation of conditioned reflexes

The structural basis of the higher nervous activity The structural basis of the higher nervous activity is brain cortex and the nearest subcortical centres. is brain cortex and the nearest subcortical centres. At formation of behavior in the central nervous At formation of behavior in the central nervous system on some time are formed neuronal circuits system on some time are formed neuronal circuits of a different degree of complexity. In the of a different degree of complexity. In the environment all the time new irritants occur. environment all the time new irritants occur. Therefore in a brain cortex at each moment of time Therefore in a brain cortex at each moment of time new combinations of neurons are activated. new combinations of neurons are activated.

Thus, in the brain cortex and the subcortical Thus, in the brain cortex and the subcortical centres there is a mosaic and dynamics of centres there is a mosaic and dynamics of excitation and braking, due to performance of the excitation and braking, due to performance of the higher nervous activity. Such interactions between higher nervous activity. Such interactions between neurons give basis of thinking, emotions and neurons give basis of thinking, emotions and behavior of the person.behavior of the person.

Characteristic of conditional irritants Characteristic of conditional irritants For development of a conditioned reflex it is necessary, that any For development of a conditioned reflex it is necessary, that any

factor of an environment, which may be perceived by one of factor of an environment, which may be perceived by one of analyzer systems of an organism, occur repeatedly and acted on an analyzer systems of an organism, occur repeatedly and acted on an organism of the person or an animal. If at each occurrence this organism of the person or an animal. If at each occurrence this irritant outstrips a little or takes place simultaneously with irritant outstrips a little or takes place simultaneously with performance of any unconditioned reflex in an organism, probability performance of any unconditioned reflex in an organism, probability of development of a conditioned reflex very high. But for formation of development of a conditioned reflex very high. But for formation of a conditioned reflex still it is necessary, that the brain cortex be in of a conditioned reflex still it is necessary, that the brain cortex be in an active, awake condition. an active, awake condition.

For development of a conditioned reflex the important value has For development of a conditioned reflex the important value has optimum force of irritant, which may become conditional irritant. optimum force of irritant, which may become conditional irritant. Small force irritant does not cause a sufficient level of activity in Small force irritant does not cause a sufficient level of activity in neurons of appropriate analyzer system. In this case the conditioned neurons of appropriate analyzer system. In this case the conditioned reflex is formed slowly. Such conditioned reflex exists the short reflex is formed slowly. Such conditioned reflex exists the short period of time and then is fast inhibited.period of time and then is fast inhibited.

In real conditions irritants from the environment do not occur as In real conditions irritants from the environment do not occur as isolated factor. There are a set of similar irritants and such irritants, isolated factor. There are a set of similar irritants and such irritants, which operate simultaneously which operate simultaneously

Nervous processes, which lays in the base of Nervous processes, which lays in the base of conditioned reflexes formationconditioned reflexes formation

The opportunity spreading excitation in the central nervous The opportunity spreading excitation in the central nervous system is caused by presence in it of numerous branches of system is caused by presence in it of numerous branches of shoots of nervous cells - axons and dendrites. Shoots shoots of nervous cells - axons and dendrites. Shoots connect neurons and the nervous centres in a uniform connect neurons and the nervous centres in a uniform network. Strengthening of irritation neurons stimulates network. Strengthening of irritation neurons stimulates distribution of excitation on nervous circuits. Due to existence distribution of excitation on nervous circuits. Due to existence of such communications excitation long time may circulate on of such communications excitation long time may circulate on closed neuronal to circuits, till opportunities of synapses to closed neuronal to circuits, till opportunities of synapses to transfer impulses will be exhausted or there will be a braking transfer impulses will be exhausted or there will be a braking process in any of neurons, so the circuit will be opened.process in any of neurons, so the circuit will be opened.

The centre of excitation, which arises in a brain cortex under The centre of excitation, which arises in a brain cortex under action of conditional stimulus may be spread on neuronal action of conditional stimulus may be spread on neuronal circuits in all directions. But if simultaneously in an organism circuits in all directions. But if simultaneously in an organism the unconditioned reflex is carried out, in a zone of cortical the unconditioned reflex is carried out, in a zone of cortical representations of this reflex the prepotent centre varying a representations of this reflex the prepotent centre varying a direction spreading of excitation develops. In such a case direction spreading of excitation develops. In such a case distribution of the excitation caused by a conditional irritant, distribution of the excitation caused by a conditional irritant, will be directed aside dominants. will be directed aside dominants.

Peculiarities of dominanta Peculiarities of dominanta Dominanta (from Latin dominare - to dominate) - is the centres Dominanta (from Latin dominare - to dominate) - is the centres

of excitation prevailing in the central nervous system, which of excitation prevailing in the central nervous system, which change and subordinate to themselves activity of other nervous change and subordinate to themselves activity of other nervous centres at present. The principle of a dominant is one of main centres at present. The principle of a dominant is one of main principles of activity of the central nervous system. The Russian principles of activity of the central nervous system. The Russian scientist O.O. Ukhtomsky was formulated these principles.scientist O.O. Ukhtomsky was formulated these principles.

The prepotent centre of excitation is characterized by such The prepotent centre of excitation is characterized by such properties:properties:

1) Increase of excitability;1) Increase of excitability; 2) Stability of excitation;2) Stability of excitation; 3) Ability to summarize excitation - to accumulation of excitation 3) Ability to summarize excitation - to accumulation of excitation

from stranger irritants;from stranger irritants; 4) Ability to inhibit function of other nervous centres and reflex 4) Ability to inhibit function of other nervous centres and reflex

reactions;reactions; 5) Ability long time to keep excitation after the termination 5) Ability long time to keep excitation after the termination

(ending) of irritation, which has caused it (inertia of a dominant).(ending) of irritation, which has caused it (inertia of a dominant).

Synaptic and membrane hypothesis of conditioned Synaptic and membrane hypothesis of conditioned reflexes formationreflexes formation

It agrees when giving experimental researches, two neuron It agrees when giving experimental researches, two neuron classes take part in formation of conditioned reflexes: classes take part in formation of conditioned reflexes: command neurons which realize specific behavioral acts command neurons which realize specific behavioral acts and modulating neurons, which adjust a condition of and modulating neurons, which adjust a condition of command neurons. Before the first appearance of stimulus command neurons. Before the first appearance of stimulus and supporting reflex neurons were mainly monotouch. In and supporting reflex neurons were mainly monotouch. In process of the further development of a conditioned reflex process of the further development of a conditioned reflex neurons get ability to answer different stimulus, that is neurons get ability to answer different stimulus, that is become polytouch. After the conditioned reflex is produced, become polytouch. After the conditioned reflex is produced, again it is observed selective reaction of neurons - they again it is observed selective reaction of neurons - they answer only stimulus, which became conditional irritant.answer only stimulus, which became conditional irritant.

The synaptic hypothesis considers that the mechanism of The synaptic hypothesis considers that the mechanism of formation of a conditioned reflex is caused by change of an formation of a conditioned reflex is caused by change of an overall performance of synapses. overall performance of synapses.

The membrane hypothesis asserts that in a basis of the The membrane hypothesis asserts that in a basis of the mechanism of formation of a conditioned reflex change of mechanism of formation of a conditioned reflex change of excitability of postsyneptic membrane lays. excitability of postsyneptic membrane lays.

Classification of conditioned reflexesClassification of conditioned reflexes I. On a way of formation:I. On a way of formation: 1. Classical conditioned reflexes - are formed in natural 1. Classical conditioned reflexes - are formed in natural

conditions.conditions. 2. Tool conditioned reflexes - are developed artificially. More 2. Tool conditioned reflexes - are developed artificially. More

often they represent purposeful motor reactions. As often they represent purposeful motor reactions. As supporting stimulus for their development the unconditioned supporting stimulus for their development the unconditioned reflex causing in a laboratory animal feeling of pleasure reflex causing in a laboratory animal feeling of pleasure (effect of "award") or painful irritant, causing avoidance (effect of "award") or painful irritant, causing avoidance reaction usually serves.reaction usually serves.

II. Under the relation of conditional irritant to unconditional:II. Under the relation of conditional irritant to unconditional: 1. Natural conditioned reflexes - conditional irritant it is related 1. Natural conditioned reflexes - conditional irritant it is related

to an unconditioned reflex. For example, a smell and how a to an unconditioned reflex. For example, a smell and how a food looks have the direct relation to irritation by food of food looks have the direct relation to irritation by food of tongue receptors, which starts unconditional salivatory tongue receptors, which starts unconditional salivatory discharge reaction.discharge reaction.

2. Artificial conditioned reflexes - conditional irritant has no the 2. Artificial conditioned reflexes - conditional irritant has no the direct relation to an unconditioned reflex which serves as a direct relation to an unconditioned reflex which serves as a reinforcement. For example, the bell or a light signal in natural reinforcement. For example, the bell or a light signal in natural conditions have no the relation to unconditional salivatory conditions have no the relation to unconditional salivatory discharge reflex.discharge reflex.

Classification of conditioned reflexesClassification of conditioned reflexes (next) (next) III. On biological importance:III. On biological importance: 1. Food conditioned reflexes - provide getting food and digestion.1. Food conditioned reflexes - provide getting food and digestion. 2. Sexual conditioned reflexes - provide sexual behavior.2. Sexual conditioned reflexes - provide sexual behavior. 3. Protective conditioned reflexes - provide defensive reactions.3. Protective conditioned reflexes - provide defensive reactions. 4. Statokinetic conditioned reflexes - provide motor behavioral 4. Statokinetic conditioned reflexes - provide motor behavioral

reactions and impellent skills.reactions and impellent skills. 5. Homeostatic conditioned reflexes - are directed on maintenance 5. Homeostatic conditioned reflexes - are directed on maintenance

of a constancy of the inner environment of an organism.of a constancy of the inner environment of an organism. III. On a degree of complexity:III. On a degree of complexity: 1. Conditioned reflexes of the first order - the conditioned reflex is 1. Conditioned reflexes of the first order - the conditioned reflex is

developed on the basis of a unconditioned reflex.developed on the basis of a unconditioned reflex. 2. Conditioned reflexes of the second order - the conditioned reflex 2. Conditioned reflexes of the second order - the conditioned reflex

is developed on the basis of other conditioned reflex of the first is developed on the basis of other conditioned reflex of the first order.order.

3. Conditioned reflexes of the third order - the conditioned reflex is 3. Conditioned reflexes of the third order - the conditioned reflex is developed on the basis of a conditioned reflex of the second order.developed on the basis of a conditioned reflex of the second order.

4. Conditioned reflexes of the higher order - are formed only at the 4. Conditioned reflexes of the higher order - are formed only at the high organization of nervous system. In human formation of high organization of nervous system. In human formation of conditioned reflexes of the second - twentieth order is probably.conditioned reflexes of the second - twentieth order is probably.

Process of inhibition in the central Process of inhibition in the central nervous system nervous system

Formation of conditioned reflexes is not Formation of conditioned reflexes is not possible without process of inhibition in the possible without process of inhibition in the central nervous system. central nervous system.

Braking of spreading impulses is provided Braking of spreading impulses is provided with various mechanisms and results thus in with various mechanisms and results thus in various effects. I.P.Pavlov classifvarious effects. I.P.Pavlov classifiedied braking braking processes in the brain cortex as two groups: processes in the brain cortex as two groups: external (unconditional) and internal external (unconditional) and internal (conditional). (conditional).

External (unconditional) External (unconditional) inhibitioninhibition

The rough reflex causes unconditional braking because The rough reflex causes unconditional braking because it protects an organism from new unknown influences of it protects an organism from new unknown influences of an environment, which possibly may cause damaging an environment, which possibly may cause damaging or to warn of danger. At repeated occurrence of new or to warn of danger. At repeated occurrence of new irritant, which was no dangerous, its braking effect irritant, which was no dangerous, its braking effect decreases. Such brake irritants refer to as time or dying decreases. Such brake irritants refer to as time or dying away. There are also constant brake irritants, which away. There are also constant brake irritants, which keep brake effect long time. Pathological processes (for keep brake effect long time. Pathological processes (for example inflammatory processes) or strong irritation of example inflammatory processes) or strong irritation of proprioreceptors (for example, overflow of a urine proprioreceptors (for example, overflow of a urine bladder, a rectum) often have such a value.bladder, a rectum) often have such a value.

One more kind of external braking is security braking. It One more kind of external braking is security braking. It arises at action of very strong irritants or very long arises at action of very strong irritants or very long influence of usual force irritants. influence of usual force irritants.

Internal (conditional) braking Internal (conditional) braking This is specific process, which is characteristic for This is specific process, which is characteristic for

cerebral cortex. It demands special conditions and cerebral cortex. It demands special conditions and training. The basic condition of development of internal training. The basic condition of development of internal braking is absence of unconditional reinforcement after braking is absence of unconditional reinforcement after action of conditional irritant when the reflex is already action of conditional irritant when the reflex is already produced and functions. produced and functions.

Regular repeated action of conditional irritant without a Regular repeated action of conditional irritant without a reinforcement of it by unconditioned reflex results in reinforcement of it by unconditioned reflex results in gradual easing a conditioned reflex, and so to its gradual easing a conditioned reflex, and so to its disappearance, fading away. Such kind of braking refers disappearance, fading away. Such kind of braking refers as fading away. as fading away.

Thanking to fading away braiking the brain is released Thanking to fading away braiking the brain is released from the information which under the present conditions from the information which under the present conditions has lost the value.has lost the value.

Differential braking Differential braking

Differential brakingDifferential braking develops, if one of two develops, if one of two conditional irritants is always supported with an conditional irritants is always supported with an unconditioned reflex, and another - is not. In this unconditioned reflex, and another - is not. In this case the conditioned reflex on supported irritant is case the conditioned reflex on supported irritant is kept. Another conditional irritant, which is not kept. Another conditional irritant, which is not supported, every time causes a conditioned reflex supported, every time causes a conditioned reflex worse while it will not disappear absolutely. worse while it will not disappear absolutely.

Differential braking allows specialization of Differential braking allows specialization of conditioned reflex and is a basis of the adequate conditioned reflex and is a basis of the adequate analysis of subjects and the phenomena of an analysis of subjects and the phenomena of an environment, and also changes in the inner environment, and also changes in the inner environment of an organism.environment of an organism.

Conditional brake Conditional brake of existing of existing reflexreflex

One of versions of differential braking - a One of versions of differential braking - a conditional brake. If to add new irritant to conditional brake. If to add new irritant to conditional irritant and to repeat this combination conditional irritant and to repeat this combination many times without any reinforcement, new many times without any reinforcement, new irritant brake conditioned reflex produced earlier. irritant brake conditioned reflex produced earlier. In this case conditional irritant loses the alarm In this case conditional irritant loses the alarm action, and inhibition of conditioned reflex action, and inhibition of conditioned reflex occurs. occurs.

Conditional brake permits constantly specify Conditional brake permits constantly specify character of conditional reflex reactions for character of conditional reflex reactions for concrete irritants from an environment.concrete irritants from an environment.

Late braking Late braking

When the time interval between action of conditional and When the time interval between action of conditional and unconditional irritant is increased, the conditioned reflex unconditional irritant is increased, the conditioned reflex appears with delay. In performance of a late reflex appears with delay. In performance of a late reflex distinguish two phases - inactive, when reactions on distinguish two phases - inactive, when reactions on conditional irritant is not present, and active, when there conditional irritant is not present, and active, when there is a reflex reaction. Late braking helps to regulate work is a reflex reaction. Late braking helps to regulate work of internal visceral organs (for example, regulation of internal visceral organs (for example, regulation secretion of the stomach after meal), develop skill to wait secretion of the stomach after meal), develop skill to wait and to keep energy in case of strong irritation.and to keep energy in case of strong irritation.

Braking in brain cortex is carried out by braking neurons. Braking in brain cortex is carried out by braking neurons. Most likely, this function is performed by star cells. It is Most likely, this function is performed by star cells. It is established, that on the mechanism of braking in a brain established, that on the mechanism of braking in a brain cortex is caused by postsynaptic hyperpolarizing. It is cortex is caused by postsynaptic hyperpolarizing. It is caused basically by change of permeability of Cl- caused basically by change of permeability of Cl- channels of postsynaptic membrane. The basic channels of postsynaptic membrane. The basic neurotransmitter in braking neurons is gamma-neurotransmitter in braking neurons is gamma-aminobatteric acid.aminobatteric acid.

Stages of coditioned reflex Stages of coditioned reflex activity activity

Stage of generalization of a Stage of generalization of a conditioned reflex conditioned reflex

Stage of specialization of a conditioned Stage of specialization of a conditioned reflex reflex

Inhibition of the conditioned reflexInhibition of the conditioned reflex

Age peculiarities of inhibition Age peculiarities of inhibition Braking of conditioned reflexes is possible since the first days Braking of conditioned reflexes is possible since the first days

of life of the child, basically with the help of external braking. of life of the child, basically with the help of external braking. At children of the first year of life both external and internal At children of the first year of life both external and internal braking easily arises. Long action of irritant can brakes even braking easily arises. Long action of irritant can brakes even rough reaction. Immaturity of the brain cortex neurons in rough reaction. Immaturity of the brain cortex neurons in newborn children causes fast development of braking newborn children causes fast development of braking process.process.

Conditional braking in the first years of life of the child is Conditional braking in the first years of life of the child is advanced very poorly. The force of all kinds of internal braking advanced very poorly. The force of all kinds of internal braking and speed of braking of conditioned reflexes increased with and speed of braking of conditioned reflexes increased with age. Children till 4 years of life distinguish irritants according age. Children till 4 years of life distinguish irritants according to one attribute - color or shape usually. Integrative functions to one attribute - color or shape usually. Integrative functions of the brain develop quickly. 5-6 year children already of the brain develop quickly. 5-6 year children already differentiate irritants according to 2-4 attributes. Ability to differentiate irritants according to 2-4 attributes. Ability to allocate the basic essential component among set of irritants allocate the basic essential component among set of irritants develops later - by 10-17 years. In old age internal braking is develops later - by 10-17 years. In old age internal braking is disturbed, that decreases workability of a person.disturbed, that decreases workability of a person.

Ability to security braking raises with aging, the excitation and Ability to security braking raises with aging, the excitation and braking ratio in the central nervous system is broken.braking ratio in the central nervous system is broken.

Coordination of functions in a brain Coordination of functions in a brain cortex cortex

All kinds of activity of the person are based on coordination of All kinds of activity of the person are based on coordination of functions in a brain cortex due to processes of excitation and functions in a brain cortex due to processes of excitation and braking. In a healthy organism processes of excitation and braking. In a healthy organism processes of excitation and braking in the central nervous system are in dynamic balance.braking in the central nervous system are in dynamic balance.

Processes of excitation and braking in the central nervous Processes of excitation and braking in the central nervous system are in complex cooperation and influence to each system are in complex cooperation and influence to each other. I.P.Pavlov has established such laws of excitation and other. I.P.Pavlov has established such laws of excitation and braking interaction. Excitation arising in any centre inhibits braking interaction. Excitation arising in any centre inhibits other centres. Concentration promotes processes of other centres. Concentration promotes processes of differentiation and an induction. Around of the centre of differentiation and an induction. Around of the centre of excitation there are centres of braking, and around of the excitation there are centres of braking, and around of the centres of braking - the centres of excitation. I.P.Pavlov has centres of braking - the centres of excitation. I.P.Pavlov has named it as cortical mosaic. But cells of the brain all time named it as cortical mosaic. But cells of the brain all time pass from exciting condition in braking and on the contrary. pass from exciting condition in braking and on the contrary. This phenomenon is named dynamics of excitation and This phenomenon is named dynamics of excitation and braking in a brain cortex.braking in a brain cortex.

Cycle of dream and wakefulness Cycle of dream and wakefulness

Processes of excitation and braking in the central nervous Processes of excitation and braking in the central nervous system, as well as other functions of an organism have daily system, as well as other functions of an organism have daily cycle. The cycle of dream and wakefulness is one of vital cycle. The cycle of dream and wakefulness is one of vital needs of the organism. The basic function of dream is needs of the organism. The basic function of dream is restoration of physical and mental forces, which allows restoration of physical and mental forces, which allows maximal adaptation to change of conditions of the external maximal adaptation to change of conditions of the external and internal environment. and internal environment.

Dream is alternation of different functional conditions of the Dream is alternation of different functional conditions of the brain. During dream brain activity is reconstructed. There is brain. During dream brain activity is reconstructed. There is a consolidation and processing of the information, which has a consolidation and processing of the information, which has arrived during wakefulness. In dreaming information moves arrived during wakefulness. In dreaming information moves from the short-term memory in the long-term. Activity of from the short-term memory in the long-term. Activity of neurons in different departments of the brain cortex and neurons in different departments of the brain cortex and subcortical nerve centres during dream remains practically subcortical nerve centres during dream remains practically same as well as during wakefulness.same as well as during wakefulness.

Physiological characteristic of Physiological characteristic of dream dream

According to modern representations, dream consists of According to modern representations, dream consists of two qualitatively various conditions - slow and fast dream. two qualitatively various conditions - slow and fast dream. Slow dream is divided on some stages, according to Slow dream is divided on some stages, according to changes on electroencephalogram. changes on electroencephalogram.

The first stage is characterized by oppression of the basic The first stage is characterized by oppression of the basic alpha-rhythm, which is gradually replaced with low alpha-rhythm, which is gradually replaced with low amplitude waves of different frequency. amplitude waves of different frequency.

The second stage is characterized by periodic occurrence The second stage is characterized by periodic occurrence of dream spindles. of dream spindles.

The third and fourth stage is characterized by gradual The third and fourth stage is characterized by gradual increase on electroencephalogram of high amplitude slow increase on electroencephalogram of high amplitude slow deltas-waves. These stages correspond to deep dream.deltas-waves. These stages correspond to deep dream.

Nerve substrate of dream Nerve substrate of dream

Numerous brain structures, which take part in the Numerous brain structures, which take part in the organization of dream, are located in the brain stem and organization of dream, are located in the brain stem and were joined in somnolence system. Nucleus in the brain were joined in somnolence system. Nucleus in the brain partition, in hypothalamus, serotoninaergic neurons in partition, in hypothalamus, serotoninaergic neurons in nucleus of a seam and thalamic synchronizing system nucleus of a seam and thalamic synchronizing system concern to these structures. concern to these structures.

Formation of fast dream connects with reticular nucleus of Formation of fast dream connects with reticular nucleus of the midbrain and limbic structures of the brain. the midbrain and limbic structures of the brain.

Reticular inhibitory area is located medially and ventrally in Reticular inhibitory area is located medially and ventrally in the medulla. This area can inhibit the reticular facilitory the medulla. This area can inhibit the reticular facilitory area of the upper brain stem and thereby decrease activity area of the upper brain stem and thereby decrease activity in the superior portions in the b5rain as well. One of the in the superior portions in the b5rain as well. One of the mechanisms for this is to excite serotoninergic neurons ar mechanisms for this is to excite serotoninergic neurons ar crucial points in the brain.crucial points in the brain.

Factors that cause dream Factors that cause dream

There are four groups of factors which cause dream: There are four groups of factors which cause dream: 1) endogenous factors caused by exhaustion and 1) endogenous factors caused by exhaustion and

somnolence substances; somnolence substances; 2) endogenous cyclic processes in an organism; 2) endogenous cyclic processes in an organism; 3) unconditional reflex irritants as darkness, rest, 3) unconditional reflex irritants as darkness, rest,

position of a body, touch monotony, influence of position of a body, touch monotony, influence of temperature, atmospheric pressure; temperature, atmospheric pressure;

4) conditioned reflexes to the certain conditions of 4) conditioned reflexes to the certain conditions of dream, time of day, its duration.dream, time of day, its duration.