Fusiform gyrus: anatomy, functions and areas.
This area of the brain is involved in visual processing, among other functions.
The fusiform gyrus is a structure of the brain, in the form of a convoluted gyrusIt is involved in various processes related to visual processing, understanding the meaning of written text or recognizing faces, among other functions.
As we will see below, damage to this structure causes serious sensory-perceptual disturbances.
In this article we explain what the fusiform gyrus is, its location and structure, its functions and 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 brain gyrus that is part of the temporal lobe and occipital lobe involved in aspects such as visual recognition of words and faces or the identification of categories.
This gyrus was described for the first time in 1854 by the anatomist Emil Huschkewho labeled this structure with this 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 its characteristic wrinkled appearance with which we are all familiar. These folds increase the total surface area of the brain, allowing more neuronal nuclei to be grouped together and, therefore, also increasing the capacity to process information.
Location and structure
At the neuroanatomical level, the fusiform gyrus is one of the major structures embedded in the ventral temporal cortex. This brain 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 (laterally). . The fusiform gyrus is composed of two portions: an anterior temporal portion and a posterior occipital portion.. The more anterior part of its temporal portion lies close to the cerebral peduncles and is usually curved or pointed, while the occipital portion lies below the lingual gyrus.
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, together with the inferior and medial temporal gyri.
Brodmann areas classify the different parts of the cerebral cortex according to their involvement in different cognitive and behavioral functions, forming a topographical map of the brain that helps neuroscience professionals to better understand the functioning of each brain structure.
Functions
The main function of the fusiform gyrus involves visual information processingincluding object identification and differentiation. In addition to high-level visual processing, this brain structure is involved in cognitive processes such as memory, multisensory integration and perception.
Regarding language, this brain area is involved in aspects such as semantic categorization, word retrieval and generation, metaphor comprehension or the connection between orthographic and phonological components; 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 may have a close functional relationship with the angular gyrus, as 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 may be involved in the following neurological systems related to the processing and recognition of visual information:
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Color processing
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Facial recognition
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Body recognition
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Word recognition
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Identification of features within categories
The fusiform area of the faces
The fusiform area of faces is perhaps the best known structure of this brain region. It is located on the lateral surface of the middle of the fusiform gyrus and plays a key role in face identification, including recognition of one's own face.
Currently, there is an ongoing debate in the neurological community, There is currently an ongoing debate in the neuroscientific community as to whether this region is solely dedicated to face processing or whether it is also involved in face recognition. or whether it is also involved in the recognition of other objects. One hypothesis (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 arises from the observation that this area is not fully developed until adolescence, despite the fact that infants already show some ability to differentiate faces, such as their mothers', and a preference for female faces. MRI studies have also not confirmed that this area is involved in these functions.
However, the fusiform gyrus and fusiform face area is not the only brain region that facilitates face identification. Although the fusiform area of faces is an important component, a network of different neural nuclei of the cortex capable of recognizing faces is required, including areas adjacent to the occipital lobe (the main area responsible for visual processing).
Related disorders
One of the best known disorders related to damage to the fusiform gyrus is prosopagnosia or visual blindness, a condition characterized by the inability to recognize familiar faces (including one's own). This disorder can result from isolated lesions in the fusiform area of the fusiform gyrus faces.
Other functions involved in visual processing, such as word processing, are known to remain intact in patients with prosopagnosia; when acquired, it usually results from a lesion in the fusiform gyrus and usually occurs in adults, whereas in congenital prosopagnosia the subject never develops the ability to recognize faces.
Another condition that can result from 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 hearing certain sounds.
The most common subtypes of synesthesia include: color grapheme, which consists of associating any sign or letters with a certain color; and color music, when the individual sees various colors depending on the type of music he or she listens to.
Finally, another condition that has been linked to lower activation and lower density of the gray matter of the fusiform gyrus is dyslexia, a disorder that causes confusion and impaired accuracy and fluency in reading,
Bibliographic references:
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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.
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Snell, R. S. (2007). Clinical neuroanatomy. Ed. Médica Panamericana.
(Updated at Apr 13 / 2024)