The fusiform gyrus is a gyrus-shaped structure of the brain 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 its location and structure are, what its functions and main areas are, as well as the most common disorders related to damage to this brain structure.
The fusiform gyrus is a gyrus of the brain that is part of the temporal lobe and 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 gyri and grooves that give this organ that wrinkled appearance that is so characteristic and that we all know. These folds increase the total surface area of the brain, allowing more neuronal nuclei to be grouped together and, therefore, also increasing the ability to process information.
Location and structure
At a neuroanatomical level, the fusiform gyrus is one of the largest structures inserted in the ventral temporal cortex. This cerebral gyrus is located on the basal surface of the temporal and occipital lobes, between the parahippocampal gyrus and lingual gyrus (medially), and the inferior temporal gyrus (laterally). . The fusiform gyrus is made up of two portions: an anterior temporal portion and a posterior occipital portion The most anterior part of its temporal portion is located near the cerebral peduncles and is generally curved or pointed, while the occipital portion is located 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, along with the inferior and medial temporal gyri.
Brodmann’s areas classify the different parts of the cerebral cortex according to their involvement in different cognitive and behavioral functions, forming a topographic map of the brain that helps professionals in the field of neuroscience to better understand the functioning of each brain structure.
Features
The main function of the fusiform gyrus involves processing 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, understanding metaphors 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 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 the processing and recognition of visual information:
The fusiform area of the faces is, perhaps, the best known structure of this region of the brain. It is located on the lateral surface of the middle of the fusiform gyrus and plays a critical role in face identification, including recognition of one’s own face.
Currently, There is an open debate in the neuroscientific community about whether this region is dedicated solely to processing faces 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 does not fully develop until adolescence, despite the fact that babies already show a certain ability to differentiate faces, such as that of their mothers, and a preference for female faces. MRI studies have also not 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 faces is an important component, a network of different neuronal nuclei of the cortex capable of recognizing faces is required, including the 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 (even one’s own). This disorder may result from isolated lesions in the fusiform area of the sides of the fusiform gyrus.
Other functions involved in visual processing, such as word processing, are known to remain intact in patients with prosopagnosia; When this is acquired, it generally 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 occur due to damage to structures related to the fusiform gyrus is synesthesia, a neurological condition that causes the 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: the color grapheme, which consists of associating any sign or letters with a certain color; and music in color, when the individual sees various colors depending on the type of music he listens to.
Finally, another condition that has been related to lower activation and lower density of the gray matter of the fusiform gyrus is dyslexia, a disorder that causes confusion and alteration of accuracy and fluency in reading.
