Somatosensory Cortex: Parts, Functions And Associated Pathologies
Each region of the human brain has specific functions and positions, which range from controlling the voluntary and involuntary movement of our muscles, enabling the production of language or receiving and interpreting all the sensations that come from our environment.
This last function is possible thanks to the somatosensory cortex, a very specific brain area that we will talk about throughout this article. In addition, we will describe their specific regions and what happens when they suffer some type of injury.
The concept of somatosensory cortex refers to a specific brain area located in the parietal lobe As its name indicates, this lobe is located under the parietal bone of the skull and in terms of size, the parietal lobe is one of the largest among those that make up the skull.
Among all the areas that define the temporal lobe, the somatosensory cortex is responsible for processing and treating sensory information that comes from the dermis, muscles and joints.
Among the functions of the somatosensory cortex is that of receive and interpret all the information that comes from the touch system Sensations of pain, temperature, pressure, as well as the ability to perceive the size, texture and shape of objects are also possible thanks to this section of the cerebral cortex.
In the same way, the somatosensory area of the brain is also responsible for receiving and transmitting information related to the position in which our body is located with respect to the space that surrounds it.
In summary, the main functions of the somatosensory cortex are:
Finally, each of the specific areas within the somatosensory cortex are specialized in interpreting sensory information from certain specific areas of our body. These areas are divided between the primary somatosensory area and the somatosensory association area, which are described in the third and fourth points of this same article.
Layers of the somatosensory cortex
Like the rest of the cerebral cortex, the somatosensory cortex is made up of a series of layers that have their own well-defined functions. Specifically, The somatosensory cortex is made up of six layers of nervous tissue
The first of these layers is the outermost one, the one that is closest to the brain surface. Among its functions is to send sensitive signals that stimulate the fourth layer. In addition, both the first and second layers of tissue receive signals that control the level of excitability of the sensory system.
As for the second and third layers of the somatosensory cortex, the neurons that compose it are responsible for sending, through the corpus callosum, signals to related regions of the corresponding cerebral cortex of the opposite hemisphere.
Finally, the fifth and sixth layers have as their main and only function send neural signals to the deepest areas of the nervous system
Primary somatosensory area
As specified at the beginning of the article, the somatosensory cortex is divided into two specific areas. The first of them is the primary somatosensory area. This area is the main person in charge of the treatment of somatic sensations
The information in which these sensations are stored is sent by receptors that are located throughout the body. These receptors receive information from the outside related to touch, pain and temperature and information that allows us to know what position or situation our body is in. At the same moment that these receptors perceive any of these sensations, they transmit the information to the primary somatosensory cortex through the nerve fibers found in the thalamus.
The primary somatosensory cortex refers to areas 1, 2 and 3 of the 52 brain regions described by Brodmann, which They are located specifically in the postcentral gyrus occupying both the lateral and medial areas.
As mentioned in the first point, each of the regions of the somatosensory cortex, in this case the primary somatosensory cortex, is specialized in receiving information from a specific area of our body. This arrangement is a function of the level of sensitivity of the different areas of the body, so very sensitive areas such as the lips, hands or genitals, which have a large number of nerve endings, require many more neural circuits and an area in the much more extensive cortex.
There is a graphic or somatotopic representation of this distribution of the primary sensory cortex. This picture It is known as the sensory or Penfield homunculus It represents a map of the cerebral cortex that shows how the different organs and senses of the body have a specific place in the brain.
Besides. In the sensory homunculus, the size of the organs represented is a function of the number of nerve endings it has and the functional importance of the specific area. That is, the more terminations, the larger the size of the representation.
Any type of injury or deterioration caused in this area can cause numerous alterations in the ability to perceive sensations. Among these dysfunctions are:
Somatosensory association area
The second region of the somatosensory cortex is known as the somatosensory association area or cortex. It produces the union and integration of all the information corresponding to general sensations
Thanks to this area of the cortex, we can recognize and identify the stimuli and objects that surround us; since it allows the evaluation and understanding of their general characteristics.
To do this, this association area, located in Brodmann areas 5 and 7, receives bundles of fibers that come from the primary somatosensory area and are loaded with sensory information ready to process.
Lesions of the somatosensory association cortex
In cases where this region suffers any type of damage or degradation, the ability to perceive general sensations of the environment is maintained. However, the brain is completely incapable of integrating and make sense of this information
This is the case of agnosias, in which the main problem consists of a deficit in the recognition of objects and people.
