Somatosensory cortex: parts, functions and associated pathologies.
This region of the brain is very important, as it integrates information from many senses.
Each region of the human brain has specific functions and functions, ranging from controlling the voluntary and involuntary movement of our muscles, enabling the production of language or receiving and interpreting all the sensations coming from our environment.
This last function is possible thanks to the somatosensory cortex, a very specific brain area of the brain.This last function is possible thanks to the somatosensory cortex, a very specific brain area that we will discuss in this article. In addition, we will describe its specific regions and what happens when they suffer some kind of lesion.
What is the somatosensory cortex?
The concept of somatosensory cortex refers to a specific brain area located in the parietal lobe.. As its name suggests, 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 the one responsible for processing and dealing with information of a sensory nature coming from the dermis, muscles and joints.
Among the functions of the somatosensory cortex is to receive and interpret all information coming from the dermis, muscles and joints. receive and interpret all the information that comes from the tactile 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 surrounding space.
In summary, the main functions of the somatosensory cortex are:
- Processing of pain sensations.
- Processing of tactile information.
- Processing of thermal sensations.
- Processing of vibratory sensations.
- Voluntary movements of the hands.
- Movements of the orofacial musculature.
- Voluntary swallowing.
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 area of association, which are described in the third and fourth points of this 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, somatosensory cortex is made up of six layers of nervous tissue..
The first of these layers is the outermost, the one closest to the brain surface. Among its functions is to send sensory 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 in charge of sending, through the corpus callosum, signals to the related regions of the corresponding cerebral cortex of the opposite hemisphere.
Finally, the fifth and sixth layers have as their main and only function to send neuronal signals to the corresponding regions of the cerebral cortex of the opposite hemisphere. to send neuronal signals to the deeper 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 these is the primary somatosensory area. This area is the main area responsible for the processing of somatic sensations..
The information in which these sensations are stored is sent by receptors located throughout the body. These receptors receive information from the outside regarding touch, Pain and temperature and the information that allows us to know in what posture or situation our body is in. As soon as these receptors perceive any of these sensations, they transmit the information to the primary somatosensory cortex through nerve fibers located in the thalamus.
The primary somatosensory cortex refers to areas 1, 2 and 3 of the 52 brain regions described by Brodmann, which are located specifically in the circumthalamus. are located specifically in the postcentral gyrus, occupying both the lateral and lateral zones.The primary sensory gyrus refers to areas 1, 2 and 3 of the 52 brain regions described by Brodmann, which are located in the postcentral gyrus.
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 body areas, so that very sensitive areas such as the lips, hands or genitals, which have a large number of nerve endings, require many more neural circuits and a much larger area in the cortex.
There is a graphic or somatotopic representation of this distribution of the primary sensory cortex. This image is known as the sensory or Penfield homunculus.. It represents a map of the cerebral cortex showing how the different organs and senses of the body have a specific place in the brain.
In addition, 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 endings, the larger the size of the representation.
Lesions of the primary somatosensory cortex
Any type of lesion or impairment in this area can cause numerous alterations in the ability to perceive sensations. in the ability to perceive sensations. Among these dysfunctions are:
- Decreased or loss of pain and thermal sensations.
- Alterations in the ability to perceive one's own body position and movements.
- Impairment of tactile sensations and functions.
Somatosensory area of association
The second region of the somatosensory cortex is known as the somatosensory association area or cortex. It is in this area that the the union and integration of all the information corresponding to the general sensations of the senses..
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.
For this purpose, this association area, located in Brodmann areas 5 and 7, receives fiber bundles coming from the primary somatosensory area and loaded with sensory information ready for processing.
Lesions of the somatosensory association cortex
In cases where this region suffers any kind of damage or degradation, the ability to perceive the general sensations of the environment is maintained. However, the brain is completely unable to integrate and make sense of this information. 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.
(Updated at Apr 13 / 2024)