Healthy cortical development through adolescence and early adulthood

Natalie J Forde,Aaron F Alexander-Bloch,Lizanne J S Schweren,Catharina A Hartman,Lisa Ronan,Jan K Buitelaar,Barbara Franke,Marcel P Zwiers,Dirk J Heslenfeld,Jaap Oosterlaan,Pieter J Hoekstra,Stephen V Faraone

doi:10.1007/s00429-017-1424-0

Abstract

Adolescence is a period of significant brain changes; however, the effects of age and sex on cortical development are yet to be fully characterized. Here, we utilized innovative intrinsic curvature (IC) analysis, along with the traditional cortical measures [cortical thickness (CT), local gyrification index (LGI), and surface area (SA)], to investigate how these indices (1) relate to each other and (2) depend on age and sex in adolescent cortical development. T1-weighted magnetic resonance images from 218 healthy volunteers (age range 8.3–29.2 years, M[SD] = 16.5[3.4]) were collected at two sites and processed with FreeSurfer and Caret software packages. Surface indices were extracted per cortex area (frontal, parietal, occipital, temporal, insula, and cingulate). Correlation analyses between the surface indices were conducted and age curves were modelled using generalized additive mixed-effect models. IC showed region-specific associations with LGI, SA, and CT, as did CT with LGI. SA was positively associated with LGI in all regions and CT in none. CT and LGI, but not SA, were inversely associated with age in all regions. IC was inversely associated with age in all but the occipital region. For all regions, males had larger cortical SA than females. Males also had larger LGI in all regions and larger IC of the frontal area; however, these effects were accounted for by sex differences in SA. There were no age-by-sex interactions. The study of IC adds a semi-independent, sensitive measure of cortical morphology that relates to the underlying cytoarchitecture and may aid understanding of normal brain development and deviations from it.

Highlights

The structural changes that occur in the brain during development are yet to be fully characterized
Multiple magnetic resonance imaging (MRI) studies of brain development have investigated cortical indices; most frequently volume (Gogtay et al 2004; Lenroot et al 2007) and the indices that contribute to volume—surface area (SA) and cortical thickness (CT) (Sowell et al 2007; Shaw et al 2008; Ostby et al 2009; Raznahan et al 2011; Brown et al 2012; Amlien et al 2016)—and local gyrification index (LGI) (Raznahan et al 2011; Shaw et al 2012)
Within the LGI model, the inclusion of SA was seen to eliminate all significant effects of sex

Summary

Introduction

The structural changes that occur in the brain during development are yet to be fully characterized. Multiple magnetic resonance imaging (MRI) studies of brain development have investigated cortical indices; most frequently volume (Gogtay et al 2004; Lenroot et al 2007) and the indices that contribute to volume—surface area (SA) and cortical thickness (CT) (Sowell et al 2007; Shaw et al 2008; Ostby et al 2009; Raznahan et al 2011; Brown et al 2012; Amlien et al 2016)—and local gyrification index (LGI) (Raznahan et al 2011; Shaw et al 2012) Despite this little has been described about the relationship of the different indices to each other or the regional effects of age and sex. The biological determinants of cortical development are complex and highly heritable (Hevner 2006; Ronan and Fletcher 2015; Jernigan et al 2016)

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