Inferior temporal gyrus: characteristics and functions

The inferior temporal gyrus is a brain structure located in the lower part of the temporal lobe and an area that we know is responsible for perception and visual discrimination, as well as other functions that have been investigated later, such as arithmetic processing and numbers.

In this article we explain what the inferior temporal twist is, what is its structure and location, what functions does it perform in the brain and what are the main disorders associated with damage to this brain structure.

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Inferior temporal gyrus: definition, structure and location

The inferior temporal twist is a gyrus located, as its name suggests, in the lower part of the temporal lobe. This lobe consists of three convolutions on its lateral surface: the superior, the medial and the inferior, which we will talk about throughout the article.

The convolutions or gyri are the folds that give that wrinkled appearance to the cerebral cortex, the most developed area of ​​the brain. brain and the one that is in charge of superior cognitive functions such as thought, language, planning or decision making decisions.

The inferior temporal gyrus is, as we mentioned, one of the three convolutions of the temporal lobe, one of the 6 main lobes of which each cerebral hemisphere consists and whose main functions involve auditory language management, participation in speech comprehension systems, visual recognition of objects or face identification, among other.

The inferior temporal gyrus is located at the lower lateral border of each cerebral hemisphere. below the medial temporal gyrus and behind with the inferior occipital gyrus. It extends around the inferolateral border to the inner surface of the temporal lobe, where it is bounded by the inferior sulcus.

It should also be noted that the main source of blood supply to this brain area comes from the four temporal branches of the artery middle cerebral sulcus that emerge from the lateral sulcus or fissure of Silvio, a slit that crosses the entire brain transversely from its base and through both sides.

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functions

The inferior temporal twist is a cerebral gyrus involved in visual object recognition and visual image processing, due to its connection with areas of the inferior occipital gyrus that form the occipital lobe, the main brain structure related to visual perception and interpretation and recognition of images, as well as spatial recognition or discrimination of movements and colors.

The inferior temporal gyrus also seems to be specialized in the interpretation and processing of numbers. In a study carried out in Palo Alto (United States) it was found that the inferior temporal area was activated in a differentiated and meaningful way when participants were presented with different numbers and their digits (p. eg “45” or “9”), which did not happen if the same was done with letters (“forty-five” or “nine”) or with homophone words (p. eg “Hun” instead of “1”).

Although it was already known that this area of ​​the brain was involved in the processing of visual information, with this and other investigations it was possible to reach the conclusion that this region was also involved in the arithmetic processing of numbers.

On the other hand, in another study carried out in Japan using functional magnetic resonance it was possible to verify that the left inferior temporal gyrus played an important role in writing logograms (system of characters or signs that represent a meaning by themselves, used in languages ​​such as Chinese) and, by extension, in other non-alphabetic languages.

Disorders related to damage to this structure

Lesions in a brain structure such as the inferior temporal gyrus can lead to disorders such as visual agnosia, which implies an inability to identify, recognize and interpret visual stimuli. When unilateral damage occurs, the functional specialization of the cerebral hemispheres: only lesions on the right side affect visual functions superiors. And why is this happening?

In most people, the left hemisphere is the dominant one when it comes to language, as well as the elaboration and interpretation of visual stimuli; while the right or non-dominant hemisphere would be specialized in non-verbal material and information, such as face recognition and emotional facial expressions. For this reason, only the higher visual functions are affected when damage occurs in the right temporal area.

Another common disorder when a person suffers damage to the inferior temporal gyrus and adjacent structures is prosopagnosia or facial blindness, which causes an inability to recognize and discriminate faces, which can also lead to problems in doing the same with objects or places.

Several studies have also concluded that damage to temporal lobe structures, specifically in the inferior and medial temporal zone, can cause problems related to semantic memory, responsible for recognizing the meaning of objects, vocabulary or knowledge of character general. This is what is observed in semantic dementia, a neurodegenerative disease characterized by the gradual loss of this type of memory, both verbally and non-verbally.

Finally, it should be noted that in some investigations it has been possible to conclude that lesions in the inferior temporal gyrus would result in an agraphia of logographic writing systems, such as kanji (logograms used in the Japanese language) or Chinese characters. In agraphia, the person's ability to write correctly is affected and, normally, it usually occurs together with other language disorders such as aphasia and alexia.

Bibliographic references:

Clark, D. L., Boutros, N. N., & Mendez, M. F. (2012). The brain and behavior: neuroanatomy for psychologists. Modern Handbook. Noble, A. C., Allison, T., & McCarthy, G. (1994). Word recognition in the human inferior temporal lobe. Nature, 372(6503), 260-263. Snell, R. S. (2007). clinical neuroanatomy. Pan American Medical Ed.