Localization of functions in the brain (1968)

Forest.

Bears in the forest.

Leaves of a tree with dew.

The bird feeds the chicks.

Sea surf.

Mimosa leaves close after touching them.

The man looks at the instruments.

The brain.

Nerve cells.

Open books, with works on the study of the brain.

Portrait of the French physician Paul Brock.

Paul Broca discovered morphological changes in the cerebral cortex in people with speech disorders.

Broca concluded that the posterior third of the inferior frontal gyrus controls speech.

Portrait of the German psychiatrist Karl Wernicke.

Wernicke described another area - the posterior third of the superior temporal gyrus.

Violation of which, led to a violation of the understanding of speech.

Experiment.

Physiologists, irritating the central gyrus of the cortex with a current, found that this leads to muscle contraction.

However, scientists Goltz and Lashley insisted on the equipotentiality of different parts of the brain.

By removing areas of the cortex, they found out that the disorders depend not so much on the site of the operation, but on the mass of the removed brain.

After removing 1/3 of the bark, the main motor reactions of the rat are almost not disturbed.

Removal of 2/3 of the cortex leads to significant violations of motor activity.

Areas of the cerebral cortex responsible for certain functions.

The title page of the work of I.P. Pavlov "Lectures on the work of the cerebral hemispheres".

Monument to I.P. Pavlov.

I.P. Pavlov with students in the vivarium of the Institute.

Experiment with a dog and a cat with a mouse.

Visual analyzer.

The analyzer has a peripheral part (eye), a conductive part (optic nerve), a lateral cranial body and a cortical part of the analyzer.

In this part of the cortex, the final formation of the visual image takes place.

The resulting impulses enter the motor area.

From here the command to move is given.

Phylogenetically, the cerebral cortex is the most recent formation of the central nervous system.

The brain consists of several departments.

The medulla oblongata.

Varoli's brain.

The cerebellum.

The midbrain.

The intermediate brain.

The ultimate brain.

The thickness of the bark is 2.5-3.0 mm.

3/4 of the entire surface of the bark is located in the furrows.

The area of the crust is 1700-2000 cm2.

The cortex consists of glial cells, fibers and nerve cells (neurons).

There are 12-14 billion neurons in the human brain.

Cartoon explaining the composition of the cerebral cortex.

I.P. Pavlov established that the cortical end of the cortical analyzer has its own center and elements scattered in other parts of the brain (periphery).

Due to layering, overlapping of analyzers with each other

it is possible to compensate for impaired functions.

By the method of evoked potentials, we determine the cortical ends of the analyzers in a cat.

When any receptor or peripheral nerve coming from the receptor is irritated, primary responses consisting of the first positive and second negative electric waves arise in the corresponding area of the cerebral cortex.

By moving the electrode along the entire cortex, it is possible to determine the center and periphery of the projection zone of this analyzer.

In the center of the projection zone, the primary responses have a shorter latency period and the largest amplitude.

At the periphery, the amplitude decreases, and the latency period increases.

Dog and cat conflict.

Irritation falling on any analyzer causes a reflex in the form of muscle movement.

Children are playing on the playground.

Rabbit on the laboratory table.

Implantation of electrodes to identify areas of nerve cells responsible for many complex functions.

An electrode is inserted.

The electrodes are reinforced on the skull with phosphate cement.

The method is harmless.

Electrical signals from subcortical structures are diverted through the electrodes.

Electrical signals are recorded.

Some structures are characterized by a special specific form of biological flows.

In case of electric shock irritation, it is possible to more accurately establish the boundaries of brain regions and find out what role they play in the life and behavior of the animal.

To simplify the experiment, a pad with holes corresponding to the topography of brain structures is fixed on the animal's head.

Through it, electrodes can be inserted into different brain structures without fixing the animal.

A cartoon explaining the mechanics of the animal's sleep and wakefulness.

Irritation of areas of the brain that cause rage, fear, hunger, pleasure.

A monkey is playing with a cat.

If in animals the emotion control centers work autonomously, then in humans the main role in the regulation of emotions is played by acquired connections.

Under normal conditions, only light narrows the pupil.

When sound is repeatedly combined with light, one sound causes the effect of pupil constriction.

Having got used to controlling the pupils, you can cause them to narrow according to the task of the experimenter.

Control over vegetative functions is concentrated in the cortex, thanks to this, a person can control his emotions.

A skier descends from a ski jump.

Parachutists are flying in the sky.

A swimmer swims underwater.

Cortical ends of various analyzers.

They correspond to cytoarchitectonic fields.

There are about 50 fields in total.

The fields differ in their structure.

The groups of functionally related fields in the figure fields 17,18,19 are the cortical fields of the visual analyzer.

It is established that the fields numbered 1,3 belong to the sensitive end of the motor analyzer.

Fields 4 and 6 are associated with the transmission of the brain's order to the muscles.

From here begins the pyramidal path to the spinal cord and muscles.

Not all analyzers are equally represented in the cortex.

The size of the cortical areas is determined not by the size of the organs, but by the degree of complexity of its functions.

Correspondence of organs and cortical areas.

At the lower stages of vertebrate evolution, the cortical regions of different brain analyzers were not so clearly distinguished.

As evolution progressed, primary zones, analyzer cores, and secondary zones appeared - the periphery of analyzers.

A rat is a typical representative of the animal world with two zones of analyzers.

The designation on the rat brain of both fields.

Later, more highly organized mammals developed tertiary zones, areas of overlap, where cellular layers are most difficult to connect with other parts of the brain.

Overlap zones in the dog.

Overlap zones in humans.

A large overlap area is associated with the presence of a second human signaling system - speech and the emergence of labor activity.

An experiment on the development of conditioned reflexes in a dog.

The bark of the large hemispheres is removed from the dog.

Conditioned reflexes disappeared, and unconditional ones weakened.

The cerebral cortex is the highest regulator of animal life.

A herd of monkeys.

A man is typing on a typewriter.

The dog has normal conditioned reflexes.

After removing the core of the visual analyzer, the analysis and synthesis of complex stimuli is disrupted.

Experiment.

A micro electrode is inserted into the visual cortex of the cat.

He touched one of the neurons.

The neuron reacts to a line at an angle of 30 degrees, but does not respond to a line at an angle of 90 degrees.

Lowering the electrode deeper, we find a cell that does not respond to a line at an angle of 30 degrees, but reacts to a line at an angle of 90 degrees.

This specialization of neurons ensures localization of functions in the cortex.

In violation of the functions of the parietal-occipital fields in humans

as a result of tumors or stroke, visual-spatial disorders occur.

Cutting the frames of this movie.

Computer.

If at least one computer element breaks down, it will not be able to work.

The brain is much more reliable than a machine.

Experiment.

A healthy rat finds a way out of the maze.

When several hundred nerve cells are removed from her, she still finds her way to the exit.

Compensation of functions occurs due to the mutual substitution of brain structures.

A healthy dog had its spinal cord cut.

At first, the dog cannot control the hind limbs, because the usual afferent and efferent pathways of these muscles are interrupted.

A month has passed and the motor functions of the hind legs have recovered almost to normal.

Obviously, other pathways and other areas of the spinal cord and brain have taken over control of the affected limbs.

If the part of the cerebral cortex that directs the movements of the left upper limb is removed from the monkey, then a cut occurs.

By fixing a healthy hand, we force the monkey to use the paretic one until it learns to use it normally.

After removing the cortex of the two hemispheres, motor function is not fully restored.

The cerebral cortex plays a major role in compensating functions.

The restructuring of human skills.

The man was put on glasses in which he sees everything upside down and was not removed for several days.

At first, the person was helpless, but then there was a restructuring of skills.

After removing the glasses, it took a while for the person to return to normal perception.

Physiological mechanism of compensation of functions.

The electrode is inserted into the rabbit's brain, touches it, passes between the cells.

The electrode contacts the brain cell.

Now we act on the receptors with various stimuli.

An electric shock to the paw, the cell reacts with prolonged discharges.

The effect of a flash of light on the eye, the cell responds again.

The cell also responds to the sound signal.

Neurons that respond to the stimulation of different receptors are called polysensory neurons.

These neurons are the scattered elements of the cortical ends of the analyzers.

When cortical zones are affected, they take over their functions.

Having identified the affected areas of the brain and destroyed them by deep cooling, doctors return patients to normal life.

The doctor talks to patients.

Physical therapy and training will help recovery after surgery.

The study of localization of functions in the brain is one of the most important problems of neurophysiology.

Scientists in the laboratory.