Supramarginal Gyrus: Functions and Disorders Associated with This Brain Region

The human ability to read and write involves a large number of complex mental processes in which visual and auditory information is combined, and later motor information in the case of writing. They involve complex processing and integration, which take place in different regions of the brain.

One of the most important is Brodman’s area 40, or supramarginal gyrus Let’s see what it is like and what functions this part of the brain is responsible for.

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Supramarginal gyrus: this is what this part of the parietal lobe is like

The supramarginal gyrus is one of the gyri or convolutions of the brain, that is, one of the visible folds of the cerebral cortex. It is located in the inferior parietal lobe, just above the Sylvian fissure and closely linked to the angular gyrus and Wernicke’s area. This gyrus is present bilaterally (that is, there is one in each cerebral hemisphere) and is of great importance in allowing some complex processes to take place.

The parietal lobe is linked to a large number of basic functions in our daily lives, such as language, both oral and written, or auditory perception and participates in aspects such as orientation and memory The functions performed by the cortex of the parietal lobe are mainly linked to sensory perception and the processing and integration of information obtained by the senses.

The latter is one of the functions of the turn we are dealing with. The angular gyrus is considered an association area in which information from other regions of the brain is integrated.

Functions of the supramarginal gyrus

The supramarginal gyrus is a brain area of great importance, which, although it is essentially known for its role in language, has various functions.

1. Literacy

One of the best-known functions of the supramarginal gyrus is to allow, together with the angular gyrus, reading and writing. In order to read and write we need to be able to perform the integration of visual and sound material in such a way that we can associate phonemes and graphemes, that is, the sounds and the letters that represent them. They are both turns, the angular and the supramarginal, which also allow us to associate visual representation and meaning.

This function is what makes the supramarginal gyrus, together with Broca’s and Wernicke’s areas and the angular gyrus, one of the main brain structures for language

2. Working memory

It has been shown that apart from its role in language, the supramarginal gyrus has connections with the dorsolateral prefrontal cortex that make it a relevant area for updating working memory.

3. Learning

It has also been observed that the supramarginal gyrus participates in the acquisition of skills, especially those that involve movement. Although this is not confirmed, it is suspected that it is capable of record information regarding the position of the extremities based on memory of previous events.

4. Tactile perception

The supramarginal gyrus has been linked not only to language and cognitive aspects but also to the perception of tactile stimuli, specifically to their recognition.

Disorders and situations in which it is altered

Alteration or injury to this brain region can have different repercussions of varying severity, with alterations being visible in the supramarginal gyrus in patients with different disorders.

1. Aphasia

It is common to find involvement or alterations in this area in patients with aphasia. It is understood as such that disorder in which the understanding and/or expression of language is difficult or impossible caused by a brain injury.

The type of aphasia in which damage to the supramarginal gyrus is most common is conduction aphasia, in which the repetition of words is damaged even though the comprehension and expression of language remain unchanged.

2. Alexia

Because the supramarginal gyrus and is one of the main areas along with the angular integration between visual and auditory material, its injury or dysfunction and are linked to alexia, which imply the existence of severe difficulties when it comes to being able to interpret or read a text.

In this way, an injury to the supramarginal gyrus will mean a presumable alteration in the ability to read by not being able to correctly associate visual representation with its meaning.

3. Corporal negligence

As we have said, the supramarginal gyrus is not only involved in language but also performs other functions. Likewise, alterations in the supramarginal gyrus can also cause the presence of spatial negligence at the level of the body itself. Some problems may also appear when working memory functions correctly.

4. Schizophrenia

Apart from that, alterations of the supramarginal gyrus also appear in some mental disorders. For example, it is observed that there is a relationship between this area and auditory hallucinations in schizophrenia there is a correlation between the size of the supramarginal gyrus and their severity.