Presentation

Kelly Mahaffy^1,2,, Nabin Koirala^1,2, Nicole Landi^1,2; ¹University of Connecticut, ²Haskins Laboratories

Research on the neurobiology of reading has been instrumental for furthering our understanding of the component processes in reading and reading disability. The bulk of this work has focused on word-level reading and proximal sub-skills (e.g., phonological awareness) and has revealed robust differences between good and poor readers in brain structure and function. Relatively less work has explored the neurobiology of reading comprehension and relevant sub-skills, despite importance of reading comprehension for academic success and the substantial number of children who struggle with reading comprehension despite adequate word reading skills. Better understanding of the neurobiology that supports reading comprehension, and where/how it differs from that which supports word-level reading, should advance our understanding of the processes that contribute to comprehension difficulties. While some work has compared groups of children with specific reading comprehension deficits (SRCD) to those with word-level reading difficulties (i.e., developmental dyslexia, DD) to identify unique neural signatures of these profiles, this work has been done in relatively small, homogenous samples. Further, the two extant studies of brain structure in SRCD included only gray matter analyses, leaving white matter pathways unexplored. In our ongoing study, we are analyzing a large, open-source dataset (Child Mind Institute Healthy Brain Network) to explore brain structure in those with SRCD, DD, and typical development (TD). Gray and white matter measures, including measures of neurite orientation and dispersion (NODDI), which may be more sensitive to individual differences, will be explored. This project features a larger, more diverse sample than previous research and will contribute new information about white matter structure to the SRCD literature. MRI data are pre-processed for quality control and grey matter and white matter metrics (cortical and sub-cortical morphometries, fractional anisotropy, mean diffusivity and neurite indices) are computed using open-source toolboxes - FreeSurfer and FSL. Metrics will be compared across groups and to behavioral measures of word reading and reading comprehension. While our hypotheses are speculative, given the small extant body of literature, two previous investigations of gray matter structure in SRCD, (Bailey et al., 2016; Patael et al., 2018), lead us to hypothesize that SRCD participants will have decreased gray matter volume relative to DD and TD peers in bilateral regions that have been shown to be important for comprehension, including the inferior and superior temporal gyri and anterior cingulate, right-hemisphere frontal regions including the middle frontal gyrus and dorsolateral prefrontal cortex, and the cerebellum. Work on reading comprehension more broadly, not in SRCD (e.g., Horowitz-Kraus et al., 2014b & 2015b), guides us to expect white matter differences predominantly in the right hemisphere, including lower FA and higher MD in right superior longitudinal fasciculi. These findings, particularly those on white matter structure, will complement existing data and to help elucidate the neural architecture underlying good and poor reading comprehension.

Topic Areas: Reading, Disorders: Developmental