Objectives

In human brain development, subcortical areas always reach their volumetric peak before school age, and started fine pruning during period of children and adolescents. The morphological maturation of subcortical areas help develop the brain function and behavioral performances. Abnormal maturation may lead to different kinds of disorders on mental, neurology, emotion, or behavior. Finding out the normal growth curve of subcortical areas is meaningful to public health and every family.

Methods

429 structrual Magnetic Resonance Imaging (MRI) of 198 subjects from the 3-wave longitudinal datasets Chinese Color Nest Project (CCNP) [1] were included in the sample (105 females), aged from 6.53 to 19.97 (81 subjects for 3 waves, 69 subjects for 2 waves and 48 subjects for 1 wave). All the data were preprocessed by VolBrain ［2］ and FreeSurfer 6.0 ［3］. According to the segmentation in FreeSurfer, we selected 18 subcortical areas: Thalamus Proper, Caudate, Putamen, Pallidum, Hippocampus, Amygdala, Accumbens area, Ventral DC, and choroid plexus, bilaterally, to calculate their fractal dimensionality (FD) [4] respectively, representing the morphological index of each area. Finally using Generalized Additive Mixed Models (GAMMs) [5] to depict each area’s growth curves if it changed significantly following age.

Results

Among FDs of the 18 selected areas, only left Pallidum demonstrated significant positive correlation with age after Bonferroni correction (p = 0.0005), taking sex as covariate [figure 1]. Moreover, both FDs of left Pallidum in female (p = 0.0312) [figure 2] and male (p = 0.0056) [figure 3] had significant correlation with age.

Conclusions

FD represents the complexity of certain area, reflecting its developmental level. In this sample, left Pallidum grows significantly by age in children and adolescents, both in girls and boys. No other subcortical area has significant correlation with age. Compare to other parts, school age could be the critical period for left Pallidum.

figure 1  Growth curve of left Pallidum

figure 2  Growth curve of left Pallidum in female

figure 3  Growth curve of left Pallidum in male

Key words

Subcortical areas, Fractal dimensionality, Pallidum, growth curve, children and adolescents

Reference

1 Yang N, He Y, Zhang Z, et al. (2017). Chinese Color Nest Project: Growing up in China (in Chinese). Chin Sci Bull. 62: 3008–3022.

2 Coupé, P., & Manjón, J.V. (2016). volBrain: An Online MRI Brain Volumetry System. Front. Neuroinform..

3 Fischl, B., Liu, A., Dale, A.M., 2001. Automated manifold surgery: constructing geometrically accurate and topologically correct models of the human cerebral cortex. IEEE Trans Med Imaging 20, 70-80.

4 Madan, C. R., & Kensinger, E. A. (2017). Test–retest reliability of brain morphology estimates. Brain Informatics, 1–15. http://doi.org/10.1007/s40708-016-0060-4

5 Lin, X., & Zhang, D. (1999). Inference in Generalized Additive Mixed Models by Using Smoothing Splines. Source Journal of the Royal Statistical Society. Series B (Statistical Methodology) J. R. Statist. Soc. B, 61(2), 381–400.