The bilateral Left Cerebrum.Temporal Lobe.Inferior Temporal Gyrus.Gray Matter.Brodmann area 21 corresponds to a portion of the middle-to-inferior temporal cortex implicated in higher-order visual and auditory association processing, including object recognition, complex feature integration, and aspects of semantic and language-related functions. Cytoarchitectonically defined by Brodmann as area 21, this region exhibits a granular structure typical of association cortex and is positioned lateral to primary auditory areas and inferior to superior temporal language regions, forming part of the broader temporal association network that interfaces with both ventral visual pathways and multimodal semantic systems. There is no direct link for this exact composite region; a closely related structure is Brodmann area 21.
The inferior temporal gyrus (ITG; Brodmann area 21) in the temporal lobe has been implicated in numerous imaging‑genetics and GWAS-based brain‑structure studies, which report heritable variation in gray matter volume and cortical thickness partly influenced by loci in or near genes such as HMGA2, microtubule and axon-guidance genes, and synaptic genes identified in large consortia (e.g., ENIGMA) for temporal lobe morphometry. Genetic variants affecting BA21/ITG structure and function overlap with risk loci for neurodevelopmental and psychiatric conditions, including autism spectrum disorder, schizophrenia, major depression, and bipolar disorder, in which altered temporal lobe gray matter or activation is a recurrent finding. GWAS and candidate-gene work on language, semantic processing, and reading traits (including dyslexia-related loci such as those near DCDC2 and KIAA0319, and FOXP2-regulated networks) have linked temporal BA21 to genetic influences on higher-order language and semantic memory, consistent with its role in word and object recognition and semantic retrieval. Neurodegenerative GWAS, particularly in Alzheimer’s disease and frontotemporal dementia (e.g., APOE, CLU, MAPT), show that carriers of risk alleles exhibit greater atrophy and functional disruption in temporal association cortex, including BA21, correlating with episodic memory and semantic deficits. Overall, bilateral BA21 appears as a convergence zone where polygenic influences on cortical development, synaptic plasticity, and connectivity contribute to interindividual differences in temporal lobe structure and to vulnerability for language-related, psychiatric, and neurodegenerative disorders.
Overview generated by GPT-4o (2026).
Region ID: 97
Hemisphere: bilateral
Atlas: Talairach labels 1mm
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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