Fig. 2: Sulcal folds undergo significant deepening during the first year of postnatal life.
a 15 sulcal folds shown on the cortical surface of an infant. Each color represents a sulcus. b Timeline of sulcal emergence in utero during gestation in weeks based on work by Chi and colleagues1. c Sulcal depth (SD, in mm) displayed on an inflated cortical surface of a sample infant scanned longitudinally at 26 days (newborn), 94 days (~3 months), 227 days (~6 months), and 368 days (~12 months) (warmer colors: higher SD). d SD increases logarithmically with age in the first year. Superior temporal sulcus (pink arrow, in c) and central sulcus (black arrow, in c) are shallower at 26 days than at 368 days. Each dot: mean SD per infant. Solid line fit: represents the reverse-fit of the log-transformed LMM (Eq. 2), obtained by applying the inverse logarithmic (exponential) function to the model predictions to recover the non-linear relationship. e Estimates of SD at birth (intercept) and (f) rate of SD development (slope), calculated using an LMM relating SD and log10 (age in days) per sulcus. Error bars: standard error of the intercept and slope (N = 43 independent participants). Data shown are from the left hemisphere (LH); Right hemisphere data in Supplementary Fig. 3a–c. Abbreviations of sulcal folds in a): calcarine sulcus (calc), insular sulcus (insula), cingulate sulcus (cing), parieto-occipital sulcus (pos), central sulcus (cent), precentral sulcus (precent), collateral sulcus (cos), superior temporal sulcus (sts), postcentral (postcent), superior frontal sulcus (sfs), intraparietal sulcus (ips), lateral occipital sulcus (los), inferior frontal sulcus (ifs), occipital temporal sulcus (ots), and inferior temporal sulcus (its). Note: the newborn infant in (c) is part of our larger infant data set and is excluded from the remaining analyses due to unusable qMRI data.
