The bilateral Left Cerebrum.Frontal Lobe.Postcentral Gyrus.Gray Matter.Brodmann area 4 region corresponds to primary motor cortex (M1), a somatotopically organized cortical field crucial for the initiation and execution of voluntary movements. Located in the precentral gyrus of the frontal lobe along the anterior bank of the central sulcus, Brodmann area 4 contains large pyramidal neurons (including Betz cells) whose axons contribute to the corticospinal tract, providing direct and indirect control over spinal motor neurons. This area exhibits a motor homunculus representation, with distinct territories controlling different body parts, and plays key roles in fine motor control, force modulation, and integration of motor commands with sensory feedback from adjacent somatosensory regions.
The bilateral Left Cerebrum.Frontal Lobe.Postcentral Gyrus.Gray Matter.Brodmann area 4 (primary motor cortex region, though the “postcentral gyrus” label partly reflects atlas-specific naming) has been implicated in genetic studies primarily through cortical morphology and neuropsychiatric GWAS rather than single-gene associations. Large-scale imaging genetics consortia (e.g., ENIGMA, UK Biobank analyses) have shown that cortical thickness and surface area in primary motor and adjacent sensorimotor regions are highly polygenic, with variants in genes involved in neurodevelopment, synaptic signaling, and cytoskeletal organization (such as those near FOXP1, TBR1, and various glutamatergic pathway loci) contributing to individual differences in motor cortex structure. GWAS of motor-related traits (e.g., fine motor skills, grip strength, general physical activity) often implicate sensorimotor cortex activation patterns, and imaging–genetic correlation work has linked polygenic scores for educational attainment, intelligence, and neuroticism to structural and functional variation in BA4 and neighboring regions. Moreover, case–control and PRS-based imaging genetics studies in schizophrenia, bipolar disorder, major depression, autism spectrum disorder, and attention-deficit/hyperactivity disorder have reported altered gray matter volume and cortical thickness in primary motor/sensorimotor cortex, with the degree and spatial pattern of these changes partially tracking the burden of common risk variants. Although no single variant is uniquely or specifically tied to the Talairach 2 mm label for BA4, the region is consistently involved in distributed genetic effects on brain development, motor control, and broader cognitive–psychiatric phenotypes.
Overview generated by GPT-4o (2026).
Region ID: 835
Hemisphere: bilateral
Atlas: Talairach labels 2mm
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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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