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Elsevier, NeuroImage, (124), p. 1044-1053, 2016

DOI: 10.1016/j.neuroimage.2015.09.046

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Topology of Genetic Associations between Regional Grey Matter Volume and Intellectual Ability: Evidence for a High Capacity Network

This paper is made freely available by the publisher.
This paper is made freely available by the publisher.

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Data provided by SHERPA/RoMEO

Abstract

Intelligence is associated with a network of distributed grey matter areas including the frontal and parietal higher association cortices and primary processing areas of the temporal and occipital lobes. Efficient information transfer between grey matter regions implicated in intelligence is thought to be critical for this trait to emerge. Genetic factors implicated in intelligence and grey matter may promote a high capacity for information transfer. Whether these genetic factors act globally or on local grey matter areas separately is not known. Brain maps of phenotypic and genetic associations between grey matter volume and intelligence were made using structural equation modeling of 3T MRI T1-weighted scans acquired in 167 adult twins of the newly acquired U-TWIN cohort. Subsequently, structural connectivity analyses (DTI) were performed to test the hypothesis that grey matter regions associated with intellectual ability form a densely connected core. Grey matter regions associated with intellectual ability were situated in the right prefrontal, bilateral temporal, bilateral parietal, right occipital and subcortical regions. Regions implicated in intelligence had high structural connectivity density compared to 10,000 reference networks (p=0.031). The genetic association with intelligence was for 39% explained by a genetic source unique to these regions (independent of total brain volume), this source specifically implicated the right supramarginal gyrus. Using a twin design, we show that intelligence is genetically represented in a spatially distributed and densely connected network of grey matter regions providing a high capacity infrastructure. Although genes for intelligence have overlap with those for total brain volume, we present evidence that there are genes for intelligence that act specifically on the subset of brain areas that form an efficient brain network.