Fusiform gyrus: anatomy, functions and areas

The fusiform gyrus is a structure of the brain, in the form of a gyrus, involved in different processes that have to do with visual processing, understanding the meaning of a written text or recognizing faces, among other functions.

As we will see later, damage to this structure causes serious sensory-perceptive alterations.

In this article we explain what the fusiform gyrus is, what is its location and structure, what are its functions and its main areas, as well as the most common disorders related to damage to this brain structure.

What is the fusiform gyrus?

The fusiform gyrus is a gyrus of the cerebrum that is part of the temporal lobe and of the occipital lobe involved in aspects such as the visual recognition of words and faces or the identification of categories.

This gyrus was first described in 1854 by the anatomist Emil Huschke., who labeled this structure with that name because it was wider in the middle than at its ends, with a shape similar to that of a spindle.

It should be noted that the cerebral cortex contains a multitude of convolutions and grooves that give this organ that characteristic wrinkled appearance that we all know. These folds increase the total surface area of ​​the brain, thus allowing more neuronal nuclei to be grouped together and thus also increasing the ability to process information.

location and structure

At the neuroanatomical level, the fusiform gyrus is one of the largest structures attached to the ventral temporal cortex. This gyrus is located on the basal surface of the temporal and occipital lobes. between the parahippocampal gyrus and the lingual gyrus (medially), and the inferior temporal gyrus (sideways).. The fusiform gyrus is composed of two portions: an anterior temporal portion and a posterior occipital portion.. The most anterior part of its temporal portion lies close to the cerebral peduncles and is therefore It is generally curved or pointed in shape, while the occipital portion lies below the gyrus. lingual.

The collateral sulcus separates the fusiform gyrus from the parahippocampal gyrus, and the occipitotemporal sulcus separates it from the inferior temporal gyrus. It should be noted that the fusiform gyrus is part of Brodmann's area 37, along with the inferior and medial temporal gyri.

The Brodmann's areas classify the different parts of the cerebral cortex according to their involvement in different cognitive and behavioral functions, forming a map topography of the brain that helps professionals in the field of neuroscience to better understand the functioning of each structure cerebral.

functions

The main function of the fusiform gyrus involves the processing of visual information, including the identification and differentiation of objects. In addition to high-level visual processing, this brain structure participates in cognitive processes such as memory, multisensory integration, or perception.

With regard to language, this area of ​​the brain is involved in aspects such as semantic categorization, word retrieval and generation, metaphor comprehension, or the connection between orthographic components and phonological; at the level of memory processing, it participates in the recognition of true and false memories, as well as in spontaneous encoding.

It is also believed that the fusiform gyrus could have a close functional relationship with the angular gyrus, since this structure is involved in color processing. The fusiform gyrus communicates with the visual pathway and the angular gyrus, which would allow the association of colors and shapes.

On the other hand, although the exact functional relevance of the fusiform gyrus remains unclear, it has been suggested that it could be involved in the following neurological systems related to information processing and recognition visual:

• color processing

• facial recognition

• body recognition

• word recognition

• Identification of characteristics within categories

The fusiform area of ​​the faces

The spindle-shaped area of ​​the faces is perhaps the best-known structure in this region of the brain. It lies on the lateral surface of the middle of the fusiform gyrus and plays a critical role in face identification, including recognizing one's own face.

Currently, there is an open debate in the neuroscientific community about whether this region is dedicated solely to face processing or if it is also involved in the recognition of other objects. One of the hypotheses (known as the experience hypothesis) suggests that this region would be important for discriminating and individualizing visually similar objects. For example, when a chess expert identifies a pawn or a queen.

One of the controversies surrounding this region stems from the observation that this area is not fully developed until the adolescence, despite the fact that babies already show some ability to differentiate faces, such as their mothers, and a preference for faces feminine. Neither have magnetic resonance studies confirmed that this area participates in these functions.

However, the fusiform gyrus and the fusiform area of ​​faces are not the only brain region that facilitates face identification. Although the fusiform area of ​​the faces is an important component, a network of different neural nuclei of the brain is required. cortex capable of recognizing faces, including the areas adjacent to the occipital lobe (the main area responsible for processing visual).

Related disorders

One of the best known disorders related to damage to the fusiform gyrus is the prosopagnosia or visual blindness, a condition characterized by the inability to recognize familiar faces (including one's own). This disorder may result from isolated lesions in the fusiform area of ​​the faces of the fusiform gyrus.

Other functions involved in visual processing, such as word processing, are known to remain intact in patients with prosopagnosia; when it is acquired, it usually results from a lesion in the fusiform gyrus and usually occurs in adults, while in congenital prosopagnosia the subject never develops the ability to recognize faces.

Another condition that can be caused by damage to structures related to the fusiform gyrus is synesthesia, a neurological condition that causes stimulation of one sensory pathway to generate an involuntary experience in another sensory pathway; for example, seeing colors when certain sounds are heard.

The most common subtypes of synesthesia include: color grapheme, which consists of associating any sign or letter with a certain color; and music in color, when the individual sees various colors depending on the type of music he listens to.

Lastly, another condition that has been associated with less activation and less density of the gray matter of the fusiform gyrus is dyslexia, a disorder that causes confusion and impaired reading accuracy and fluency,

Bibliographic references:

• McCarthy, G., Puce, A., Gore, J. C., & Allison, T. (1997). Face-specific processing in the human fusiform gyrus. Journal of cognitive neuroscience, 9(5), 605-610.

• Snell, R. S. (2007). clinical neuroanatomy. Pan American Medical Ed.