Mapping Cortical Area Organization in Healthy Adults Using High-Resolution HCP Data: Insights into Human Brain Function and Morphology

/Abstract The outer layer of the mammalian brain, the cerebral cortex, contains a mosaic of functionally and anatomically distinct areas. Understanding the organization and individual variability of these cortical areas is fundamental for decoding the unique brain function (i.e., individual differences in cognition, behavior, personality, psychiatric symptoms, substance use, susceptibility to brain disorders, etc.) and the heritability of these variations. High- resolution structural and functional magnetic resonance imaging data from 1071 healthy young adults aged 22- 35 years (485 males and 586 females, including monozygotic and dyzgotic twins, non-twin siblings, and unrelated individuals) provided by the Human Connectome Project (HCP) have revealed a group-average map of 180 cortical areas per hemisphere. Recent methodological advances have led to the generation of individual subject cortical area parcellations that show significant differences from the group average map. The proposed work focuses on understanding individual variability in human cortical areal organization, estimating the heritability of this variability, and identifying its behavioral correlates. To achieve such understanding, Aim 1 of this proposal will investigate cortical areas in terms of their size, scaling, shape, topology, and number, also testing the bilateral symmetry across the left and right hemispheres. The reproducibility of novel findings will be evaluated by the HCP test-retest dataset consisting of 205 young adults scanned twice at 3T or 7T. Aim 2 will estimate the heritability of the variations identified in Aim 1 by disentangling the genetic and environmental contributions using the twin-pair HCP data. Finally, Aim 3 will examine the relationship between individual variability in cortical organization and and individual behavioral measures from the HCP Individual Behavioral Assessment dataset. The expected outcomes of the proposed work include i) exploration of individual cortical area variability by developing measurable, quantitative, imaging-based metrics that objectively and reproducibly determine individual variability, ii) investigation of the reproducible existence and prevalence of atypical areal topologies, iii) determination of the reproducible prevalence of missing or extra areas among individuals, iv) estimation of the heritability of individual cortical area variability, and v) relation of individual cortical area variability to differences in individual behavior. The broad, long-term objective of this proposal is to map the brain-behavior relationship among individuals, while elucidating the genetic and environmental influences on this mapping, to better understand mental function and dysfunction that lead to adaptive and maladaptive behaviors, and to inform personalized approaches to diagnosis, treatment, and prevention of mental illnesses. The proposed work and the training plan will be conducted in the Glasser and Van Essen lab at Washington University in St. Louis and will prepare the applicant to become a successful independent researcher studying the organization of the brain in health and disease. Project Number: 1F32MH140418-01 | Fiscal Year: 2025 | NIH Institute/Center: National Institute of Mental Health (NIMH) | Principal Investigator: Nagehan Demirci | Institution: WASHINGTON UNIVERSITY, SAINT LOUIS, MO | Award Amount: $79,552 | Activity Code: F32 | Study Section: Special Emphasis Panel[ZRG1 F02B-E (20)] View on NIH RePORTER: https://reporter.nih.gov/project-details/1F32MH14041801