Poster #16 - Neurobiological relationships to orthographic processing after controlling for phonological ability

• In Event: 3-053 - Poster Session 10
  In Poster Session: PS 10 Section - Biological Processes: Neuroscience and Genetics

Integrative Statement

Phonological awareness (PA) involves analyzing words by their sounds (Wagner, Torgesen & Rashotte, 1994), and some believe poor PA to be the ‘core’ deficit in reading disability (RD; (Liberman & Shankweiler, 1991; Rack, Snowling, & Olson, 1992; Stanovich, 1988). Orthographic processing, another reading component skill, includes the ability to identify words by sight without decoding them. Orthographic processing promotes efficiency of reading skills such as fluency and comprehension (Cone et al., 2008; Perfetti, 1985). Therefore, it is important to consider how poor orthographic processing manifests in those with RD. Limited research has examined fusiform structure in relation to orthographic processing (Krafnick et al., 2011; Linkersdörfer et al., 2012), but fMRI research suggests PA is important in the development of the fusiform for orthographic processing (Cao et al., 2006; McNorgan & Booth, 2015). Nevertheless, researchers typically do not control for PA skill when examining orthographic processing in quantitative MRI studies. Thus, the purpose of our study was to investigate volume-orthographic processing relationships between those with and without RD while controlling for PA. We hypothesized that children without RD (non-RD) would display greater volume differences in the fusiform in relation to orthographic processing as compared to those with RD.

Participants included children 8-12 years of age from a community sample (n=106, 50.9% male, 86.8% Caucasian). They included 17 children with RD, 42 with ADHD, 16 with both disorders (RD/ADHD) and 31 who were typically developing. For this project, the participants were split into two groups. One group had RD (children with RD only and those with comorbid RD/ADHD) and the other did not (children who were typically developing or had ADHD only). The children were administered a measure of PA from the Comprehensive Test of Phonological Processing (CTOPP) known as Elision. Orthographic processing was measured by a composite score representing the average raw score on two experimental measures: homophone decision and correct spelling amongst similar phonetic foils.

An independent sample t-test was used in CAT to compare children with and without RD while controlling for TICV, age, gender and Elision. The contrast tested for regions with larger values in non-RD participants (compared to the RD group) that were linked to better scores in orthographic processing while controlling for PA. The between group contrast (uncorrected, p = .001) was significant. In comparison with the RD group, the non-RD group showed significant differences in the left cerebellar tonsil/posterior hemisphere, occipital regions such as the lingual gyrus and cuneus, left precentral/superior frontal, left postcentral gyrus, and bilateral inferior and middle temporal regions including the left fusiform gyrus.

This study supported our hypothesis of greater fusiform volume in the non-RD group as compared to the RD group in relation to orthographic processing. It also revealed larger volumes in other areas implicated in RD when controlling for PA: cerebellum, occipital and temporal. Hence, these regions may be contributing to successful orthographic processing in non-RD readers. Findings also suggest multiple regions may be contributing to orthographic deficits in RD.

Authors

• Hannah Travis, Southern Illinois University in Carbondale
  Presenting Author

• Audreyana C. Jagger-Rickels, Southern Illinois University-Carbondale
  Non-Presenting Author

• Michelle Y. Kibby, Southern Illinois University-Carbondale
  Non-Presenting Author