| Resilient readers are characterized by impaired phonological processing despite skilled text comprehension. We investigated orthographic and semantic processing in resilient readers to examine mechanisms of compensation for poor phonological decoding. Using magnetic resonance imaging, we compared radial expansion, gray matter thickness, and gray matter asymmetry between resilient readers, proficient readers, and poor readers. Resilient readers showed deficits on phonological tasks similar to those shown by poor readers. We obtained no evidence that resilient readers compensate via superior orthographic processing, as they showed neither exceptional orthographic skill nor increased reliance on orthography to guide pronunciation. Resilient readers benefited more than poor or proficient readers from semantic relationships between words and experienced greater difficulty when such relationships were not present. We suggest, therefore, that resilient readers compensate for poor phonological decoding via greater reliance on word meaning relationships. Anatomically, poor and resilient readers share reduced leftward asymmetry in a temporo-parietal region that is active during print-to-sound conversion tasks (Booth, et al., 2002). Poor readers, but not resilient readers, show reduced radial expansion in the ventral frontal lobes, regions active during semantically demanding tasks (Fiez, 1997). Resilient show more leftward asymmetry of gray matter thickness of the medial surface. In some portions of the medial surface, this asymmetry was associated with the degree of semantic priming; in other regions, no associations with our experimental tasks were seen. Previous functional imaging studies suggest that the medial frontal region may be involved in maintaining text coherence (Kuperberg, Lakshmanan, Caplan, & Holcomb, 2006) or error monitoring (Kiehl, Liddle, & Hopfinger, 2000). We suggest that resilient readers' reliance on compensatory processing may relate to morphology of the medial surface. We explored relationships between brain morphology and specific reading skills. Phonological processing ability was positively associated with gray matter thickness in the medial frontal region. Orthographic processing ability was negatively associated with gray matter and radial expansion in frontal, temporal, and parietal regions. Comprehension ability was positively associated with radial expansion across much of the cortical surface. This study represents the first attempt to characterize resilient readers in terms of both behavioral profile and brain anatomy. |
