Mapping cortical brain asymmetry in 17,141 healthy individuals worldwide via the ENIGMA Consortium

Abstract

Hemispheric asymmetry is a cardinal feature of human brain organization. Altered brain asymmetry has also been linked to some cognitive and neuropsychiatric disorders. Here, the ENIGMA (Enhancing NeuroImaging Genetics through Meta-Analysis) Consortium presents the largest-ever analysis of cerebral cortical asymmetry and its variability across individuals. Cortical thickness and surface area were assessed in MRI scans of 17,141 healthy individuals from 99 datasets worldwide. Results revealed widespread asymmetries at both hemispheric and regional levels, with a generally thicker cortex but smaller surface area in the left hemisphere relative to the right. Regionally, asymmetries of cortical thickness and/or surface area were found in the inferior frontal gyrus, transverse temporal gyrus, parahippocampal gyrus, and entorhinal cortex. These regions are involved in lateralized functions, including language and visuospatial processing. In addition to population-level asymmetries, variability in brain asymmetry was related to sex, age, and intracranial volume. Interestingly, we did not find significant associations between asymmetries and handedness. Finally, with two independent pedigree datasets ( = 1,443 and 1,113, respectively), we found several asymmetries showing significant, replicable heritability. The structural asymmetries identified and their variabilities and heritability provide a reference resource for future studies on the genetic basis of brain asymmetry and altered laterality in cognitive, neurological, and psychiatric disorders.

Alterations in Cortical Morphology after Neonatal Stroke: Compensation in the Contralesional Hemisphere?

“…In this work, a surface‐based analysis approach was used in order to study the structural brain abnormalities in seven‐year‐old children that sustained a NAIS. Taking into account the asymmetry of the brain (Toga and Thompson, ; Kong et al , ), structural changes were compared for the LLP and RLP groups separately. This allowed us to study the influence of the lesion lateralization on the structural changes of the brain for each hemisphere.…”

“…In addition, we do not consider the moderate number of subjects per patient group, a relevant risk for false positives (n = 19 for LLP and n = 15 for RLP). Fifteen is considered to be the minimal number of sample subjects in order to conduct reliable statistical analysis of this kind (Kong et al , ). Furthermore, when doing uncorrected comparisons (using P < 0.001) of LLP versus HC and RLP versus HC, our findings did not change.…”

“…Patients with the lesion in the left (LLP) and right hemisphere (RLP) were processed separately. By keeping the original orientation of the brain without flipping the image in the left-right direction we eliminate the ambiguity and inaccuracy that arises from the asymmetry of the brain (Kong et al, 2018). However, after further examination four patients were eliminated due to poor segmentation results (for more details please refer to section MRI Acquisition and processing), leaving 34 patients divided into the LLP and RLP groups.…”

Automatic analysis of cross‐sectional cerebral asymmetry on 3D in vivo MRI scans of human and chimpanzee

“…One limitation of the present study is the lack of full knowledge of handedness in the healthy participants, although no significant association was identified between brain asymmetries and handedness in a meta‐analysis of a large database of 17,141 healthy individuals (Kong et al, ). In addition, the finding in the present study was based on the captive Yerkes chimpanzee group, which may not fully reflect the natural populations of chimpanzees and other great apes.…”

Objective PET study of glucose metabolism asymmetries in children with epilepsy: Implications for normal brain development

“…Only regions with significant correlations (after false discovery rate correction) in at least one of the genders are listed. Interestingly, in a recent large MRI study, assessing cortical brain asymmetries from 17,141 healthy subjects, the authors did not find significant associations with handedness (Kong et al, 2018). Our study group included children as young as 1 year of age, whose overall brain volume is lower than the volume of older children.…”