Mapping cortical asymmetry and complexity patterns in normal children

This study reports the first comprehensive three-dimensional (3D) maps of c ortical patterns in children. Using a novel parametric mesh-based analytic technique applied to high-resolution Tl-weighted MRI scans, we examined age (6-16 years) and gender differences in cortical complexity (the fractal di mension or complexity of sulcal/gyral convolutions) and asymmetry of 24 pri mary cortical sulci in normally developing children (N = 24). Three-dimensi onal models of the cerebral cortex were extracted and major sulci mapped in stereotaxic space. Given the documented age-related changes in frontal lob e functions and several neuroimaging studies that have reported accompanyin g volumetric changes in these regions, we hypothesized that, with age, we w ould find continued modifications of the cerebrum in frontal cortex. We als o predicted that phylogenetically older regions of the cerebrum, such as ol factory cortex, would be less variable in anatomic location across subjects and with age. Age-related increases in cortical complexity were found in b oth left and right inferior frontal and left superior frontal regions, poss ibly indicating an increase in secondary branching with age in these region s. Moreover, a significant increase in the length of the left inferior fron tal sulcus and a posterior shifting of the left pre-central sulcus was asso ciated with age. Three-dimensional asymmetry and anatomic variability maps revealed a significant left-greater-than-right asymmetry of the Sylvian fis sures and superior temporal sulci, and increased variance in dorsolateral f rontal and perisylvian areas relative to ventral regions of the cortex. The se results suggest increases in cortical complexity and subtle modification s of sulcal topography of frontal lobe regions, likely reflecting ongoing p rocesses such as myelination and synaptic remodeling that continue into the second decade of life. More studies in a larger sample set and/or longitud inal design are needed to address the issues of normal individual variation and sulcal development. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.