The bilateral Left Cerebrum.Occipital Lobe.Inferior Occipital Gyrus.Gray Matter.Brodmann area 18 corresponds to the secondary visual cortex (V2) located in the occipital lobe, adjacent to the primary visual cortex (BA17). This region is organized in a retinotopic manner and plays a key role in early-stage visual processing, including contour integration, orientation discrimination, binocular disparity, and figure–ground segregation. Neurons in Brodmann area 18 receive strong feedforward input from BA17 and send projections to higher-order visual association areas, contributing to the extraction of more complex visual features and the integration of visual information necessary for perception and recognition. Although Talairach labels specify the “Left Inferior Occipital Gyrus,” the functional properties of BA18 are largely similar across hemispheres, supporting bilateral visual processing. There is no direct Wikipedia article for this exact Talairach label; a closely related structure is Brodmann area 18.
The bilateral inferior occipital gyrus gray matter in Brodmann area 18 (secondary visual cortex) has been implicated in several genetic and GWAS-based associations, largely through imaging genetics studies rather than region-specific candidate gene work. Twin and family studies show high heritability of occipital cortical thickness and surface area, with genome-wide associations implicating variants in genes involved in neurodevelopment, synaptic function, and axonal guidance (e.g., HMGA2, TBR1, and multiple loci in WNT and semaphorin pathways) that broadly influence occipital and visual cortex morphology. Large-scale GWAS of brain structure (e.g., ENIGMA and UK Biobank) have identified SNPs associated with occipital lobe cortical thickness and surface area, some of which overlap with loci for general cognitive ability, educational attainment, and neurodevelopmental traits, suggesting pleiotropic effects on both visual cortex development and higher-order cognition. Genetic associations with disorders that show functional or structural abnormalities in BA18—including schizophrenia, bipolar disorder, major depression, autism spectrum disorder, and dyslexia—often involve polygenic risk scores that correlate with altered activation or gray matter measures in occipital visual regions, although these are typically not specific to the inferior occipital gyrus alone. Visual cortical response characteristics linked to BA18, such as contrast sensitivity and face or object processing, show heritable components and have been connected to variants in genes related to glutamatergic and GABAergic signaling, but these findings remain relatively diffuse and not confined to a single Brodmann area. Overall, genetic influences on BA18 appear to reflect broader neurodevelopmental and neuropsychiatric risk architectures affecting early visual cortex organization, rather than highly localized gene–region relationships.
Overview generated by GPT-4o (2026).
Region ID: 250
Hemisphere: bilateral
Atlas: Talairach labels 2mm
Full Quality Version: Download MP4
Full Quality Version: Download MP4
Wali Sidiqyar*, Gaurav Rudravaram*, Elyssa M. McMaster, Trent M. Schwartz, Adam M. Saunders, Kurt G. Schilling, Bennett A. Landman "Introducing SPINS: A Shared Public Visualization Library of Neuroanatomical Structures." Medical Imaging with Deep Learning- short paper
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