The left precentral region in the AAL2 atlas corresponds primarily to the left precentral gyrus, which contains much of the primary motor cortex (M1, Brodmann area 4) responsible for voluntary movement execution. This region is organized somatotopically, with different segments controlling distinct body parts—classically forming the motor homunculus, where lateral portions represent face and hand movements and more medial portions represent trunk and lower limb. Neurons in the left precentral gyrus send corticospinal projections that predominantly decussate to control contralateral (right-sided) musculature, enabling fine motor control and coordination. Functionally, this area is critical for initiating and modulating skilled movements, motor learning, and integration of premotor and sensory inputs into precise motor commands.
The left precentral gyrus (primary motor cortex) in the AAL2 atlas has been implicated in numerous imaging genetics and GWAS studies, primarily through its cortical thickness, surface area, and activation patterns rather than direct SNP-to-region mappings. Variants in genes involved in neurodevelopment and synaptic function—such as BDNF, COMT, APOE, CNTNAP2, and CACNA1C—have been associated with structural and functional alterations in motor cortex regions, including the left precentral gyrus, often in the context of broader cortical measures. Large-scale GWAS of brain morphology (e.g., ENIGMA and UK Biobank studies) have identified polygenic influences on motor cortex thickness and surface area, with overlapping loci linked to general cognitive ability, educational attainment, and neurodevelopmental traits. In clinical genetics, abnormalities in the left precentral region have been reported in disorders with motor or psychomotor components, such as Parkinson’s disease, amyotrophic lateral sclerosis, cerebral palsy, attention-deficit/hyperactivity disorder, and schizophrenia, where risk variants and polygenic scores correlate with altered motor cortex structure or activation. Stroke and motor recovery genetics (e.g., variants in BDNF and genes influencing plasticity) also show associations between genotypes and functional reorganization of the left precentral gyrus. Overall, genetic influences on the left precentral region appear highly polygenic and pleiotropic, shared with global brain development and cognitive traits rather than being specific to this single AAL2-defined area.
Overview generated by GPT-4o (2026).
Region ID: 2001
Hemisphere: left
Atlas: AAL2
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Full Quality Version: Download MP4
Full Quality Version: Download MP4
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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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