The brain, a complex network of specialized regions, orchestrates every thought, action, and perception. Among these regions, the lingual gyrus is a significant area, contributing to various aspects of human cognition, particularly visual interpretation. Understanding its functions provides insight into the intricate workings of the human mind.
Location of the Lingual Gyrus
The lingual gyrus is situated in the occipital lobe, the brain’s primary visual processing center. It is found on the inner, or medial, surface of this lobe, specifically between two grooves: the calcarine sulcus above it and the posterior part of the collateral sulcus below it. The gyrus extends backward to the occipital pole, the most posterior part of the brain, and anteriorly connects with the parahippocampal gyrus on the temporal lobe’s tentorial surface. This positioning places it in close proximity to the primary visual area, known as Brodmann’s area 17, which lies on both sides of the calcarine sulcus, encompassing both the lingual gyrus and the cuneus.
Visual Processing and Object Recognition
The lingual gyrus processes visual information, contributing to our ability to recognize various visual stimuli. It distinguishes between shapes and colors, and in the general identification of objects and faces. This region, along with the fusiform gyrus, is part of a larger network often referred to as visual area 4 (V4), which activates in response to color stimuli. The right lingual gyrus, in particular, is involved in perceiving and recognizing familiar landmarks and scenes, with topographical recognition in its anterior half and face identification in its posterior half. The lingual gyrus helps differentiate visual patterns and form coherent perceptions from raw visual data, contributing to the complex “what pathway” of the ventral visual stream for object identification.
Role in Reading and Language
Beyond general visual processing, the lingual gyrus plays a specific role in reading. This area activates when literate individuals read printed words and is considered a part of the “Visual Word Form Area” (VWFA). The VWFA, located in the left mid-portion of the fusiform gyrus, becomes specialized for recognizing recurring properties of writing systems, enhancing word perception for rapid reading. This system supports an orthographically specific “visual word form” system. This specialization allows for quick identification and processing of written words, converting visual symbols into meaningful linguistic information.
What Happens When the Lingual Gyrus is Affected?
Damage or dysfunction to the lingual gyrus can lead to specific neurological conditions affecting visual recognition and reading. One such condition is visual agnosia, where individuals have difficulty recognizing objects or faces despite intact vision. Another notable consequence is pure alexia, an acquired inability to read despite preserved writing and other language skills. This condition often results from lesions in the left occipitotemporal region and the splenium of the corpus callosum, which disrupts the transfer of visual information to language centers. Causes of such damage can include cerebrovascular accidents, such as strokes affecting the posterior cerebral artery, trauma, tumors, or neurodegenerative diseases.