Fractal dimension in human cortical surface: Multiple regression analysis with cortical thickness, sulcal depth, and folding area

• Published in: Human brain mapping Vol. 27; no. 12; pp. 994 - 1003
• Main Authors: Im, Kiho, Lee, Jong-Min, Yoon, Uicheul, Shin, Yong-Wook, Hong, Soon Beom, Kim, In Young, Kwon, Jun Soo, Kim, Sun I.
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.12.2006; Wiley-Liss
• Subjects: Adult; Biological and medical sciences; Brain Mapping; Cerebral Cortex - anatomy & histology; Cerebral Cortex - physiology; cortical thickness; Ear and associated structures. Auditory pathways and centers. Hearing. Vocal organ. Phonation. Sound production. Echolocation; Educational Status; Electrocardiography. Vectocardiography; Electrodiagnosis. Electric activity recording; Female; folding area; fractal dimension; Fractals; Functional Laterality - physiology; Fundamental and applied biological sciences. Psychology; Humans; Imaging, Three-Dimensional - methods; Intelligence; Investigative techniques, diagnostic techniques (general aspects); Magnetic Resonance Imaging - methods; Male; Medical sciences; multiple regression; Nervous system; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Regression Analysis; sulcal depth; Vertebrates: nervous system and sense organs; Human; Nervous system diseases; sulcal depth; Fractal dimension; Radiodiagnosis; cortical thickness; folding area; multiple regression; Regression analysis; Surface analysis; Depth
• DOI: 10.1002/hbm.20238
• ISSN: 1065-9471

Fractal dimension (FD) has been widely used to provide a quantitative description of structural complexity in the cerebral cortex. FD is an extremely compact measure of shape complexity, condensing all details into a single numeric value. We interpreted the variation of the FD in the cortical surface of normal controls through multiple regression analysis with cortical thickness, sulcal depth, and folding area related to cortical complexity. We used a cortical surface showing a reliable representation of folded gyri and manually parcellated it into frontal, parietal, temporal, and occipital regions for regional analysis. In both hemispheres the mean cortical thickness and folding area showed significant combination effects on cortical complexity and accounted for about 50% of its variance. The folding area was significant in accounting for the FD of the cortical surface, with positive coefficients in both hemispheres and several lobe regions, while sulcal depth was significant only in the left temporal region. The results may suggest that human cortex develops a complex structure through the thinning of cortical thickness and by increasing the frequency of folds and the convolution of gyral shape rather than by deepening sulcal regions. Through correlation analysis of FD with IQ and the number of years of education, the results showed that a complex shape of the cortical surface has a significant relationship with intelligence and education. Our findings may indicate the structural characteristics that are revealed in the cerebral cortex when the FD in human brain is increased, and provide important information about brain development. Hum Brain Mapp, 2006. © 2006 Wiley‐Liss, Inc.