1. Integrative and Intellectual Functions of the Brain
Higher nervous activity
Lecture is prepared by
EKATERINA ELISEEVA
Ass. Prof. of the Normal Physiology Department
Stavropol state medical university, 2015

2. Learning
is the most characteristic ability of humans and higher animals.
This process make an individual possible to change his behavior according current needs and environment changes.
Learning and memory are the functions of nervous system based on conditioned and unconditioned reflexes.

3. Conditioned reflex
Is a reflex response to a stimulus which does not elicit the response itself but acquires after repeated application with another specific stimulation that normally evokes such a response.
Conditioning = training

4. Unconditioned vs. conditioned
Inborn, inherited
Stable, constant
Activity of low nerve centers
Adequate stimulation only
Specific (for species)
Based on the certain reflex arch
Give certain adaptation
Acquired during life
May be established or abolished
Activity of cortical (higher) centers
Any stimulus may be conditioned
Individual
Based on temporary connection of neurons
Give better adaptation

5. Characteristics
Variability, which is the most characteristic feature of a  conditioned reflex, ensures the body’s adjustment to th e external environment. A conditioned signal that gives incorrect information on  th e external environment ceases to be a stimulus for  re sponsive behaviour, and the reaction to such a signal disappears. This phenomenon i s based on internal inhibition, which causes a  sensitive discrimination among stimuli according to their physiological and biological  properties and which helps the body dispense with  conditioned reflexes that are no longer biologically useful.

6. Characteristics
The conditioned reflex warns person about approach of the subsequent kinds of activity and prepares them 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 behaviour 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.

7. Classification I. According to biological importance Nutritional
Defensive
Sexual
Homeostatic, etc.
II. According to reflex reactions
Motor
Visceral
Cardiac
Secretary, etc.

8. Classification III. According to base reflexes First order reflex
Second order reflex
High order reflex
IV. According to time periods
Classic
Traced
Reflex for time

9. Classification V. According to receptors Exteroreceptive
Interoreceptive
Proprioreceptive
VI. According to basal methodic
Natural
Instrumental (Artificial)

10. Characteristics & Features
Depending on the stimulus causing the reflex, conditioned reflexes are classified as either natural or artificial.
 Natural conditioned reflexes are evoked by the inherent properties of an  unconditional reinforcement that have biological  significance for an animal, for example, the sight and smell of food. 
Artificial conditioned reflexes are evoked by stimuli  that are initially unconnected to a reinforcement, for  example, a bell, a light, or the sound of a metronome.

11. Rules for conditioned reflexes
Combination of two stimuli: conditioned stimulus must be the first in order and unconditioned stimulus must follow it.
Conditional stimulus is at first relatively neutral (indifferent) and evokes orientation reflex. The goal is to suppress this reaction by applying the conditioned stimulation several times.

12. The special reflex laboratory by I.V.Pavlov

13. The orientation reflex
has a special place among unconditioned reflexes. It is a reflex response to novelty, elicited by any sufficiently quick change in the external environment, and is outwardly expressed in alertness, listening for new sounds, sniffing, turning the eyes and head, and sometimes the whole body toward a stimulus, etc. This reflex facilitates best perception of an acting agent and has great adaptive significance. As Pavlov figuratively described it, the orientation reaction is a "What is it?" reflex.

14. Rules for conditioned reflexes
Both stimuli must be more intensive than threshold. Intensity of unconditioned stimulus must be more than intensity of conditioned one.
For example: Conditional nutritional reflex may be established if the dog is hungry. Ringing (at first neutral signal, which then becomes conditional one) is followed by some food in a few second (strong unconditional reinforce). Repetitive combination of both signals provokes formation of conditional nutritional reflex: secretion of saliva. This means that now ringing provokes secretion of saliva without any food.

15. Rules for conditioned reflexes
Combination of conditioned and unconditioned stimuli must be repetitive.
Formation of temporary connections requires normal active state of central nervous system.

16. Mechanism of conditioned reflex
Conditioned reflexes, as a rule, reproduce the structure of an unconditioned reflex, since the conditioned stimulus excites the same nerve centers as the unconditioned one. Therefore the components of the conditioned reflex are similar to those of the unconditioned reaction. They include primary components specific for the type of reflex and secondary, unspecific components. In the defensive reflex the leading role is played by I he motor component, in the nutritional reflex by the motor and secretory components.

17. Conditioned stimulus center
Unconditioned reflex center

18. PAVLOV'S CONCEPT:
Conditional reflexes are built on the basis of unconditional ones. The building of a conditional reflex is based on the formation of temporary connections between two cortical centers: (a) perceiving the conditional stimulus and (b) perceiving the unconditional one. Important role in the mechanism of interaction between different cortical regions play (a) cortico-subcortico-cortical pathways and (b) the dominant phenomenon. When conditioned and unconditioned stimuli are combined, the excitation is summated. Nervous cells of both cortical regions are involved in a rhythmic activity. Circulation of impulses along the same neuronal chains ensures the formation of temporary connections. Functional changes are important only for brief impression of traces of stimuli on the cortex ("short-term memory"). Long retention of temporary connections ("long-term memory") is based on some molecular plastic changes taking place in the synapses and neurons.

19. Biological importance of conditioned reflexes:
reflex reactions appear a certain time before actual unconditioned stimulation thus preparing the organism. Conditioned reflexes help to find food, to avoid danger in proper time, to eliminate harmful influences, etc, they are base for habits.
Reflexes may be applied in clinical and psychological practice.

20. Inhibition of higher nervous activity
External inhibition – conditioned reflex is weakened or suppressed by simultaneous excitatory process
Temporary
Permanent
Internal inhibition – inhibitory effects in the cortical center of conditioned reflex
Extinction
Differential inhibition
Conditioned inhibition
Inhibition of delay

21. Temporary inhibition
Inhibitory effect arises in a new cortical center, not in centers involved into conditioned reflex.
E.g., orientation reflex – any new stimulation suppresses current conditioned activity.
Importance – readiness to give response to a stimulus

22. Extinction
If the conditioned stimulus is repeated without unconditioned base for several times, reflex becomes extinct, suppressed.
Importance – brain does not keep reflexes and habits which are not necessary.

23. Extinction
Example of extinction: a dog has been previously conditioned to come when he hears a bell because he knows he will get food. But the previous handful of times the dog did not receive food so no longer comes when he hears the bell.
The figure is another example, applied on mouse.

24. Differential inhibition
Firstly conditioned response may be given to different stimuli rather similar to conditioned stimulus (generalization period in reflex activity).
After several repetitions response in given accurately to certain stimulus only, other are inhibited in differential manner.
Importance – the base for learning.

25. Inhibition of delay
If unconditioned base is delayed the established conditioned reflex is inhibited.
Importance - organism gives response only to stimulus applied in proper time.

26. Type of nervous system
determines the rate at which conditioned reflexes are built, the strength and stability of these reflexes, the rate of irradiation and concentration of nerve process, greater or lesser susceptibility to various influences causing pathology in higher nervous activity.

27. Nerve processes are characterized through:
Strength of excitation and inhibition
How much time is required for building conditioned reflex and for how long time period
Equilibrium in excitation and inhibition
Excitatory or inhibitory reactions prevail
Mobility of excitation and inhibition
How easily organism changes one reflex complex to the other if necessary

28. Types of nervous system
Choleric
Strong but unbalanced nerve processes characterized by predominance of excitation
Sanguine
Strong, well-balanced, highly mobile nerve processes
Phlegmatic
Strong, well-balanced, low mobile nerve processes
Melancholic
Extremely weak development of both excitation and inhibition, unbalanced, low mobile

29. This figure is an application of the four types:

31. Human’s types of nervous system
(1) Thinking type - with dominant left hemisphere
(2) Art type - with dominant right hemisphere
(3) Mixed type - with equally developed functions of left and right hemispheres
(4) Genius type – with equally overdeveloped functions of left and right hemispheres

32. Emotions
Emotion is a kind of psyco-physiological phenomenon, it is a multifaceted form of behavior, involving:
Different somatic reactions (smiling, laughing, running, etc.);
Variety of autonomic responses (heart rate changes, paleness, fainting, etc.)

33. Aspects of emotions
Cognition determines the emotion that in its type and degree is appropriate to given situation
Expression in form of somatic and autonomic activity during emotional state
Experience is the subjective aspect, basis for pleasant and unpleasant emotions
Excitement may be delight or distress

34. Nerve control of emotions
Hypothalamus is often considered as the seat of emotions. It is the principle center where various components of emotional reactions are organized into definite pattern.
Stimulation of different parts of hypothalamus shows different emotional reactions.

35. Nerve control of emotions
Thalamus – anterior nuclei, dorsomedial nucleolus, posteroventral nucleous are part of limbic system.
Cerebral cortex and limbic system – amygdaloid nucleous complex, hyppocampus, hypothalamus, thalamus, ancient cortex – form “circles” making possible prolonged analyzes of information, base for behavior and emotions.

36. Behavioral program

37. Thank you for your attention!