Developmental changes in the corpus callosum from infancy to early adulthood: a structural magnetic resonance imaging study

Abstract

Previous research has reported on the development trajectory of the corpus callosum morphology. However, there have been only a few studies that have included data on infants. The goal of the present study was to examine the morphology of the corpus callosum in healthy participants of both sexes, from infancy to early adulthood. We sought to characterize normal development of the corpus callosum and possible sex differences in development. We performed a morphometric magnetic resonance imaging (MRI) study of 114 healthy individuals, aged 1 month to 25 years old, measuring the size of the corpus callosum. The corpus callosum was segmented into seven subareas of the rostrum, genu, rostral body, anterior midbody, posterior midbody, isthmus and splenium. Locally weighted regression analysis (LOESS) indicated significant non-linear age-related changes regardless of sex, particularly during the first few years of life. After this increase, curve slopes gradually became flat during adolescence and adulthood in both sexes. Age of local maximum for each subarea of the corpus callosum differed across the sexes. Ratios of total corpus callosum and genu, posterior midbody, as well as splenium to the whole brain were significantly higher in females compared with males. The present results demonstrate that the developmental trajectory of the corpus callosum during early life in healthy individuals is non-linear and dynamic. This pattern resembles that found for the cerebral cortex, further suggesting that this period plays a very important role in neural and functional development. In addition, developmental trajectories and changes in growth do show some sex differences.

Fig 1. The samples of the corpus callosum on midsagittal MRI.

Fig 2. Regional subdivisions of the corpus callosum based on Witelson et al. (1989) and Venkatasubramanian et al. (2007).

Subregions: (1) rostrum, (2) genu, (3) rostral body, (4) anterior midbody, (5) posterior midbody, (6) isthmus, (7) splenium.

Fig 3. Scatter plots by monthly age and sex of absolute area of the each part of corpus callosum with local smoothing models (LOESS).

(a); rostrum, (b) genu, (c) rostral body, (d) anterior midbody, (e) posterior midbody, (f) isthmus, (g) splenium, (h) total corpus callosum, blue square: male (n = 61), red circle: female (n = 53), blue line: males’ LOESS, red line: females’ LOESS.

Fig 4. Rate of monthly growth change for (a) rostrum, (b) genu, (c) rostral body, (d) anterior midbody, (e) posterior midbody, (f) isthmus, (g) splenium, (h) total corpus callosum.

Positive values indicate increasing size of the area. The point of intersection on the x-axis represents the age of local maximal area. Blue line: males’ LOESS (n = 61), red line: females’ LOESS (n = 53). The arrows show the local maximum for each region calculated using LOESS. For the rostrum, there were local maxima beyond 24 months (2 years) for both females and males, 69 (5.9 years) and 132 months (11 years) old for females and 86 (7.2 years) and 122 months (10.2 years) for males. For the genu, females had two local maxima at 137 (11.5 years) and 214 months (17.1 years), whereas males had only one local maximum at 223 months (18.7 years). For the rostral body, local maxima were observed only in males (55 (4.7 years), 75 (6.3 years), and 233 months (19.5 years)). For the anterior and posterior midbodies, local maxima were observed only once for both sexes (for females at 211 (17.7 years), males at 224 months (18.8 years); for females at 243 (20.3years), males at 209 months (17.5 years), respectively). For the isthmus, splenium and entire corpus callosum, single local maxima were observed only for males (219 (18.3 years), 212 (17.8 years) and 226 months (18.1 years), respectively).