Lower temporal gyrus: features 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 were studied later, such as as arithmetic and number processing.

In this article we tell you what is the lower temporal turn, What is its structure and location, what functions it performs in the brain and what are the main disorders associated with damage to this brain structure.

    Lower time turn: definition, structure and location

    The lower temporal turn is 1 brain convolution located, as its name suggests, at the bottom of the temporal lobe. This lobe is made up of three convolutions on its lateral face: the superior, the medial and the inferior, which we will talk about throughout the article.

    Convolutions or coils are the folds that give this wrinkled appearance to the cerebral cortex, the most developed area of ​​the brain and that in charge of higher cognitive functions such as thinking, speaking, planning or making decisions.

    The lower temporal gyrus is, as we have mentioned, one of the three convolutions of the temporal lobe, one of the 6 main lobes that make up each cerebral hemisphere and the main functions involve the management of auditory language, participation in systems speech understanding, visual recognition of objects or identification of faces, among others.

    The inferior temporal gyrus is located in the lower lateral part 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 groove.

    It should also be noted that the main source of blood supply to this area of ​​the brain is from the four temporal branches of the middle cerebral artery that emerge from the lateral groove or Silvio’s cleft, a fissure that runs through the entire brain. from the base and on each side.

      the functions

      The lower temporal gyrus is a brain convolution that participates in the visual recognition of objects and the processing of visual images, For its connection with the areas of the lower occipital gyrus that form the occipital lobe, the main brain structure related to visual perception and the interpretation and recognition of images, as well as spatial recognition or discrimination of movements and colors.

      The lower temporal gyrus she also seems to be specialized in the interpretation and processing of numbers. In a study conducted in Palo Alto (United States), it was found that the lower temporal zone was activated in a differentiated and significant way when participants were presented with different numbers and their digits (for example “45” or “9 “), which would only happen if the same was done with letters (” forty-five “or” nine “) or with homophone words (for example,” huno “instead of” 1 “).

      Although this area of ​​the brain is already known to be involved in processing visual information, this research and others have found that this region is also involved in arithmetic processing of numbers.

      On the other hand, in another study carried out in Japan using functional magnetic resonance imaging, we could see that the left inferior temporal gyrus an important role in the drafting of logograms (System of characters or signs which alone represent meaning, used in languages ​​such as Chinese) and, by extension, in other non-alphabetic languages.

      Disorders related to damage to this structure

      Injury to a brain structure such as the inferior temporal gyrus can cause disorders such as visual agnosia, Which implies an inability to identify, recognize and interpret visual stimuli. In the case of a unilateral lesion, the functional specialization of the cerebral hemispheres becomes apparent: only lesions on the right side affect higher visual functions. And why does this happen?

      In most people, the left hemisphere is dominant in terms of language as well as the development and interpretation of visual stimuli; while the right or non-dominant hemisphere would specialize in non-verbal material and information, such as facial recognition and emotional facial expressions. That is why higher visual functions are affected only when damage occurs in the correct time zone.

      Another common disorder when a person sustains damage to the lower 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 doing the same with objects or places.

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

      Finally, it should be noted that some research has concluded that injury in the lower temporal gyrus would result in 1 Spelling of logographic writing systems, Such as kanji (logograms used in Japanese) or Chinese characters. Spellings affect a person’s ability to write correctly and usually occur in conjunction with other language disorders such as aphasia and alexia.

      Bibliographical references:

      Clark, DL, Boutros, NN and Méndez, MF (2012). The brain and behavior: neuroanatomy by psychologists. Modern manual. Noble, AC, Allison, T., and McCarthy, G. (1994). Word recognition in the human lower temporal lobe. Nature, 372 (6503), 260-263. Snell, RS (2007). Clinical neuroanatomy. Pan American Medical Ed.

      Leave a Comment