Performance differences on reading skill measures are related to differences in cortical grey matter structure in young adults

We investigated relations between cortical grey matter structure and individual differences in an array of literacy-related skills in a community-based sample of young adults. Whole-brain analysis revealed several structural correlates of skills related to establishing links between phonological and orthographic information. Decoding ability was positively correlated with grey matter volume (GMV) in left superior temporal sulcus, and grey matter thickness (GMT) in right superior temporal gyrus. Print exposure was negatively correlated with GMT in both left inferior frontal gyrus (pars opercularis) and the left fusiform gyrus (including the visual word form area). Both measures were also related to supramarginal gyrus (SMG), but with differential specificity: decoding was positively associated with GMV in left anterior SMG, and print exposure was negatively associated with GMT in left posterior SMG. These results refine previous functional and clinical findings by suggesting a novel role for left posterior SMG in the development of proficient reading.