Individual differences in decoding skill, print exposure, and cortical structure in young adults

ABSTRACT

This exploratory study investigated relations between individual differences in cortical grey matter structure and young adult readers’ cognitive profiles. Whole-brain analyses revealed neuroanatomical correlations with word and nonword reading ability (decoding), and experience with printed matter. Decoding was positively correlated with grey matter volume (GMV) in left superior temporal sulcus, and thickness (GMT) in right superior temporal gyrus. Print exposure was negatively correlated with GMT in left inferior frontal gyrus (pars opercularis) and left fusiform gyrus (including the visual word form area). Both measures also correlated with supramarginal gyrus (SMG), but in spatially distinct subregions: decoding was positively associated with GMV in left anterior SMG, and print exposure was negatively associated with GMT in left posterior SMG. Our comprehensive approach to assessment both confirms and refines our understanding of the novel relation between the structure of pSMG and proficient reading, and unifies previous research relating cortical structure and reading skill.

KEYWORDS:

• Individual differences
• reading and literacy
• structural MRI
• phonological decoding
• print exposure

Acknowledgements

We are grateful to Jessica Grittner for assistance with data collection, to Morgan L. Bontrager, Alexis R. Johns, Leonard Katz, Victor Kuperman, and Ashley G. Lewis for insightful comments and advice on earlier drafts of this paper, and to P. R. Nelson for support and inspiration.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Clinton L. Johns http://orcid.org/0000-0003-0593-7508

Notes

1. Although, as noted in the Method, we have reservations about using variance inflation factors (VIFs) to index multicollinearity, we nonetheless calculated them for our predictors. The VIFs converged with the results of the condition numbers: their range (1.43–6.08) was not only below the commonly recommended threshold of 10 (e.g. Cohen, Cohen, West, & Aiken, 2013; James, Witten, Hastie, & Tibshirani, 2013; Kutner, Nachtsheim, Neter, & Li, 2005), but also below a more conservative recent recommendation of 7 (Keith, 2014).

2. In line with recent recommendations (e.g. Eklund, Nichols, & Knutsson, 2017), all structural MRI data and analysis scripts are available at OpenNeuro.org, a free online repository for neuroimaging data: https://openneuro.org/datasets/ds001365/versions/00001.

3. Similarly, Goldman and Manis (2013) observed a relation between SMG and the amount of pleasure reading their participants engaged in outside of instructional settings. Although the absence of MNI coordinates in this study does not permit assessment of the locus of their SMG correlations, we mention it here as weak converging evidence for our account of pSMG’s structural relation to reader characteristics.

Additional information

Funding

This research was supported by the following grants to Haskins Laboratories from the Eunice Kennedy Shriver National Institute of Child Health and Human Development: P01 HD-01994 (Jay G. Rueckl, PI), R01 HD-040353 (Donald P. Shankweiler, PI), R01 HD-071988 (David Braze, PI), R01 HD-073288 (Julie A. Van Dyke, PI), and NRSA HD-080331 (Dave Kush, PI).