The brain is the most complex organ in the human body. The most highly organized part of it is the cortex. Thanks to its presence, a person is able to read, write, think, remember, and so on. Many scientists paid attention to the study of the structural features of the cortex. There are many works on the division of the crust into the so-called Brodmann fields. It is about them that will be discussed later in the article.
A bit of history
Mapping the surface of the brain was done by many scientists: Bailey, Betz, Economo and others. Their maps differed significantly from each other in the form of fields, their size, and quantity. In modern neuroanatomy, the fields of the brain according to Brodmann have received the greatest recognition. There are 52 fields in total.
Pavlov, in turn, subdivided all the fields into two large groups:
- centers of the first signaling system;
- centers of the second signal system.
Each center consists of a core, which plays a key role in the implementation of the function of a particular center, and analyzers,surrounding the core. It is noteworthy that the centers in the cerebral cortex regulate the functioning of organs on the opposite side of the body. This is due to the fact that the pathways of the nerve fibers cross over on their way from the center to the periphery.
The brain fields according to Brodmann are indicated by Arabic numerals, some also have a designation from which one can understand the function of a particular field.
First signaling system: location
The centers of the first signaling system are located in the Brodmann fields, which are present in both animals and humans. They are responsible for a simple reaction to an external stimulus, the formation of sensations, ideas. These centers are present in both the right and left hemispheres of the cerebral cortex. The Brodmann fields of the first signaling system are present in humans from birth and normally do not change throughout life.
These fields include:
- 1 - 3 - located in the parietal lobe of the cerebral cortex behind the central gyrus;
- 4, 6 - located in the frontal lobe anterior to the central gyrus, incorporate Betz's pyramidal cells;
- 8 - this field is located anterior to the 6th, closer to the frontal part of the frontal cortex;
- 46 - located on the outer surface of the frontal lobe;
- 41, 42, 52 - located on the so-called Geshle convolutions, on the basal part of the temporal lobe of the brain;
- 40 - located in the parietal lobe behind 1 - 3 fields, closer to the temporal part;
- 17 and 19 - located in the back of the headbrain, most dorsally from other fields;
- 11 - one of the most ancient structures, located in the hippocampus.
First signaling system: functions
The functions of the Brodmann fields in the first signal system differ depending on the localization of the center, the features of its histological structure. In general, these cores perform the following functions:
- implementation of the motor process;
- recognition of objects by touch;
- rumor;
- vision.
In order to carry out precise movement, simultaneous activation of several Broca's fields is required:
- Centers 4 and 6, whose pyramidal cells carry the impulse to the skeletal muscles and ensure their contraction.
- Field number 40, where there are centers for the implementation of complex, stereotypical movements for a particular person. These centers are formed during the life of an individual, usually during professional activity.
- Sometimes it is necessary to activate the 46th field, which is responsible for the synchronous rotation of the eyes along with the head.
Recognition of objects by touch, or stereognosy, involves fields numbered 5 and 7.
Fields 41, 42 and 52 are necessary for a person to perceive the sounds of the surrounding world. Moreover, fibers from two ears at once approach the center of hearing on one side. Therefore, damage to the cortex on the one hand does not lead to auditory impairment. The center, located in field 41, is responsible for the primary analysis of information. In the 42nd field are the centers of auditory memory. And with the help of field number 52a person can navigate in space.
Fields 17 to 19 contain the visual analyzer. By analogy with the auditory centers, the primary analysis of information takes place in the 17th field, the visual memory is located in the 18th field, and the evaluation centers and orientation are located in the 19th field.
In the 11th field are the centers of smell, in the 43rd - the centers of taste.
Second signaling system: location
The presence of the second signaling system is characteristic only for humans. It is these centers that provide higher thinking, which includes the generalization of information, dreams, logic. In fact, for normal thinking and speech, activation of all Brodmann fields is necessary, but centers can be distinguished that have their own specific functions:
- 44 - located in the back of the inferior frontal gyrus;
- 45 - located anterior to field 44, in the anterior portion of the frontal gyrus;
- 47 - placed below the two previous fields, closer to the basal part of the frontal lobe;
- 22 - one of the most anterior parts of the temporal lobe;
- 39 - located in the back of the superior temporal gyrus.
Second signaling system: functions
As noted above, Brodmann's cytoarchitectonic fields of the second signaling system are necessary for the implementation of higher nervous activity. And the main difference between a person and an animal is the ability to speak.
Broca's center is in the 45th field. It is necessary for normal motor skills of speech. It is thanks to the presence of this center that a personable to pronounce words. When it is damaged, a condition called "motor aphasia" develops.
In the 44th field is the center of writing. Impulses from this area of the cortex come to the skeletal muscles of the fingers and hand. When it is destroyed, a person loses the ability to write, which is called "agraphia".
47 field is responsible for singing. It is during the normal operation of this center that a person can sing words.
In the 22nd field is the center of Wernicke. This is where audio analysis comes into play. Thanks to the normal work of 22 fields, a person perceives words by ear.
39 field - the center of visual speech. The functioning of this field allows a person to distinguish characters written on paper. When it is damaged, a person loses the ability to read, which is called sensory alexia.
Conclusion
Cytoarchitectonic Brodmann fields are important structures of the cerebral cortex. But there are also centers free from these fields. They are located mainly in the frontal lobe, between the temporal and occipital regions. They are called associative zones.
