Conditioned reflex activity of the organism.

Conception about higher and lower nervous activity.

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

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

Determination of notion “conditioned reflexes”.

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

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

Differences of conditioned and unconditioned reflexes

Property      Unconditioned reflexes    Conditioned reflexes

Irritant         Direct adequate irritant    Direct irritants and their traces

Receptive field      Is precisely determined    Is not present a certain receptive field

Formation and reaction   Under the genetic program         On action of special conditions of the external and internal environment

Terms of occurrence of a reflex          After birth, in process of maturing nervous and endocrine system  Precisely are not determined

The central part of a reflex arch          The spinal cord, a brain stem, cortical representation of an unconditioned reflex The brain cortex and subcortical nucleus

Specific specificity          Is expressed           Not expressed

Physiological importance          Provide a survival of a species Provide behavior and the higher nervous activity

Classification of conditioned reflexes

I. On a way of formation:

1. Classical conditioned reflexes – are formed iatural conditions.

2. Tool conditioned reflexes – are developed artificially. More often they represent purposeful motor reactions. As supporting stimulus for their development the unconditioned reflex causing in a laboratory animal feeling of pleasure (effect of “award”) or painful irritant, causing avoidance reaction usually serves.

II. Under the relation of conditional irritant to unconditional:

1. Natural conditioned reflexes – conditional irritant it is related to an unconditioned reflex. For example, a smell and how a food looks have the direct relation to irritation by food of tongue receptors, which starts unconditional salivatory discharge reaction.

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

III. On biological importance:

1. Food conditioned reflexes – provide getting food and digestion.

2. Sexual conditioned reflexes – provide sexual behavior.

3. Protective conditioned reflexes – provide defensive reactions.

4. Statokinetic conditioned reflexes – provide motor behavioral reactions and impellent skills.

5. Homeostatic conditioned reflexes – are directed on maintenance of a constancy of the inner environment of an organism.

III. On a degree of complexity:

1. Conditioned reflexes of the first order – the conditioned reflex is developed on the basis of a unconditioned reflex.

2. Conditioned reflexes of the second order – the conditioned reflex is developed on the basis of other conditioned reflex of the first order.

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

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

Regularity of forming and manifestation of conditioned reflexes

Signals of conditioned reflexes.

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

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

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

Condition of forming of conditioned reflexes.

Dominanta (from Latin dominare – to dominate) – is the centers of excitation prevailing in the central nervous system, which change and subordinate to themselves activity of other nervous centers at present. The principle of a dominant is one of main principles of activity of the central nervous system. The Russian scientist O.O. Ukhtomsky was formulated these principles.

The prepotent centre of excitation is characterized by such properties:

1) Increase of excitability;

2) Stability of excitation;

3) Ability to summarize excitation – to accumulation of excitation from stranger irritants;

4) Ability to inhibit function of other nervous centers and reflex reactions;

5) Ability long time to keep excitation after the termination (ending) of irritation, which has caused it (inertia of a dominant).

Mechanisms of forming of conditioned reflexes

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

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

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

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

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

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

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

Characteristic of unconditional inhibition

Conception of inhibition

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

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

External inhibition.

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

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

Physiological meaning of unconditional inhibition is protective

Physiological importance of external braking, according to I.P.Pavlov, is protection of cells of a brain cortex against a functional exhaustion that may be caused by superfluous irritation. External braking promotes restoration of metabolic reserves and function of nervous cells if they were exhausted by superfluous activity before.

Characteristic of conditional inhibition

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

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

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

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

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

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

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

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

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

Stages of coditioned reflex activity

Mechanisms Conditions   Stages

Formation of temporary communications in a brain cortex and the subcortical centres (dominant)  Indifferent irritant outstrips unconditioned reflex or synchronize it. An awaking condition of a brain cortex, free from other kinds of activity. Sufficient force of indifferent irritant. Proper repetition of all these conditions.

          Stage of generalization of a conditioned reflex

Differential braking         Recurrence of conditions, recurrence of concrete irritant action.    Stage of specialization of a conditioned reflex

Security braking. A conditional brake. Late braking.

          Recurrence of action of conditioned irritant without unconditional reinforcement. Backlog in time of an unconditional reinforcement from conditional irritant.

          Inhibition of the conditioned reflex

Age peculiarities of inhibition. Braking of conditioned reflexes is possible since the first days of life of the child, basically with the help of external braking. At children of the first year of life both external and internal braking easily arises. Long action of irritant can brakes even rough reaction. Immaturity of the brain cortex neurons iewborn children causes fast development of braking process.

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

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

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

Studying of excitation and braking processes in cerebral cortex has grate importance for understanding of medical psychology. By the subsequent researches in laboratory and clinic both it was shown, that overstrain of excitation and braking processes results in infringements of the higher nervous activity. This underlies neurosis and other disorders.

Physiological bases of sleep

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

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

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

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

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

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

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

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

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

Functions of speech

Main functions of speech are communicative, regulatory, programming and gives general notion about surroundings. Communicative function permits exchange of information between people. Such a function is also present in animals, which use for this aim vocalization of different intensity to warn about danger or express positive and negative emotions. People use verbal signals for everything he perceives through the receptors. Words are abstraction of reality and allow generalization, processing of surrounding primary information.

Verbal instructions may direct human activity, give suggestion about proper mode of behavior. This is programming function of speech. Programming function of speech involves emotional component also, which may influence to emotional status of a person. As limbic system, which controls emotions, has direct connection with autonomic nervous system.

So speech through emotions may influence to functions of visceral organs. Physician may use this effect for psychotherapy. It is necessary remember about jatrogenic disorders also.

Central securing of language’s formation

There are two aspects of communication: sensory, involving reading, hearing of speech, and second, the motor aspect, involving vocalization and its control. It is known, that lesion of posterior portion of the superior temporal gyrus, which is called

The formation of thoughts is the function of associative areas in the brain. Wernicke’s area in the posterior part of the superior temporal gyrus is most important for this ability. Broca’s speech area lies in prefrontal and premotor facial region in the left hemisphere.

The skilled motor patterns for control of the larynx, lips, mouth, respiratory system and other accessory muscles of speech are all initiated from this area.

The skilled motor patterns for control of the larynx, lips, mouth, respiratory system and other accessory muscles of speech are all initiated from this area. Articulation means movements of mouth, tongue, larynx, vocal cords, and so forth that are responsible for the intonations, timing, and rapid changes in intensities of the sequential sounds. The facial and laryngeal regions of the motor cortex activate these muscles, and the cerebellum, basal ganglia, and sensory cortex all help control the sequences and intensities of muscle contractions.

Transmitters such as dopamine, noradrenaline, serotonin and certaieuropeptides transmit their signals by what is referred to as slow synaptic transmission. The resulting change in the function of the nerve cell may last from seconds to hours. This type of signal transmission is responsible for a number of basal functions in the nervous system and is of importance for e.g. alertness and mood. Slow synaptic transmission can also control fast synaptic transmission, which in turn enables e.g. speech, movements and sensory perception.

Development of signaling systems in children. The ability of a full-term baby to develop temporary connections of the first signaling system arises in a few days after the birth.. In the first six months of life speech sounds mean little to a child. They are simply stimuli to the auditory analyzer like any other sounds. The first signs of development of the second signaling system appear during the second half of the first year of life. If a person or an object is named and shown to a child many times, reaction to this name develops. Later after leaning a few words, a child begins to name objects itself. Finally, at a later time he uses a stock of words to communicate with other people.

Individual (typological) peculiarities of people

Type of nervous system determines rate of creation of new conditioned reflexes, strength and stability of these reflexes, intensity of external and internal inhibition, rate of irradiation and concentration of nervous processes, the capacity for induction and less or grater possibility for development of abnormalities of higher nervous activity.

I.P. Pavlov classifies types of higher nervous activity according to several attributes that considered as most reliable indices of higher nervous activity. These were intensity of the excitation and inhibition, the ratio of these processes in central nervous system and their mobility, that is rate at which excitation was replaced by inhibition and wise versa. In experimental practice the following four principle types of higher nervous activity are met:

1) strong unbalanced type, characterized by predominance of excitation over inhibition;

2) strong well-balanced active type, characterized by high mobility of nerve processes;

3) strong well-balanced passive type, characterized by low mobility of nerve processes;

4) weak type, characterized by extremely weak development of both excitation and inhibition, which cause fatigue and low workability.

Characteristic of types of higher nervous system depending on cooperation between I and II signal systems.

The analysis and synthesis of the direct stimuli from surroundings first signal system performs. This includes impressions, sensations.

This functional mechanism is common in human and animals. In the course of his social development and labor activity second signal system, which based on using verbal signals, develop. This system includes perception of words, reading and speech.

The development of the second signaling system was incredibly broadened and changed by quality of higher nervous activity of cerebral hemispheres. Words are signals of other signals. Man uses verbal signals for everything he perceives through the receptors. Words are abstraction of reality and allow generalization, processing of surrounding primary information. This gives the first general human empiricism and finally science, the instrument of man’s higher orientation in the environment and its own self.

So, second signaling system is socially determined. Outside the society, without association with other people second signaling system is not developed.

Types of higher nervous activity according to Eyzenk’s classification. The set of external manifestations of human temperament is various. G. Azenk on the base of customs of different types of temperament was revealed three personal parameters: 1) extraversion or introversion; 2) neurotizm; 3) psychotism. Extroversive person is openhearted, has high social activity, interesting in public relations. On other hand, introversive person is passive emotionally unstable and interested mainly in his inner world. It concerned peculiarities of reticular-cortical interconnections lay in the basis of this personal fiche. Introversive temperament correlates with grater activity of septal and hippocampal inhibitory system in the brain. Neurotic person is high irritable, has unbalanced emotional status even in usual conditions. Level of neutotizm correlates rate of activity of limbic and cortical interconnections in the brain. Psychotic person is highly egocentric, cool people relations and aggressive. Importance of social medium in formation of personal temperament is high. Personal fiches of temperament get brighter with age.

Attention

Determination of “attention” notion

Attention is selectiveness of psychical processes or any kind of mental activity, which helps in getting and processing the information. There are sensory, motor, intellectual and emotional forms of attention, depending to kind of activity of a person.

There are voluntary and involuntary levels of attention. Involuntary attention is present from the birth of man. Voluntary attention develops in life course, due to mental activity, formation of speech function and studying languages.

Forms and levels of attention.

Involuntary attention is controlled by lower portion of brain stem and midbrain, where centers of roof reflexes are locates. Voluntary attention appears as a result of higher cortical activity in visual, auditory, motor areas and so on.

Lesion of these cortical areas leads to such disturbances in processing special sensory information as ignore of stimuli of different modality. Intellectual attention appears because of function of prefrontal associative cortical area. The limbic system of the brain is responsible for emotional attention.

Physiological mechanisms of attention.

Involuntary attention is controlled by lower portion of brain stem and midbrain, where centers of roof reflexes are locates. Voluntary attention appears as a result of higher cortical activity in visual, auditory, motor areas and so on. Lesion of these cortical areas leads to such disturbances in processing special sensory information as ignore of stimuli of different modality. Intellectual attention appears because of function of prefrontal associative cortical area. The limbic system of the brain is responsible for emotional attention.

Memory function

The “memory” notion.

Memory function helps fixing of perceived information, keeping it in verbal form or as traces of percept stimuli and recognizing of this information in proper time. Genetic memory keeps information about body structure and forms of its behavior. Biological memory is presented in both philogenetic and ontogenetic forms. The immune memory and psychical memory for instance, belong to ontogenetic memory.

General characteristics of memory are duration, strength of keeping the information and exactness of its recognizing. In man mechanisms of perception and keeping the information are developed better, comparing to other mammalians.

According to duration is concerned short-time and long-time memory; in relation to kind of information – sensory and logic.