A comparison of cortical anatomy between college students with different reading skills Suzanne E. Welcome 1, Christine Chiarello 1, Paul Thompson 2, & Elizabeth Sowell 2 1 University of California, Riverside 2 Laboratory of NeuroImaging, University of California, Los Angeles Participants 200 university students screened 22 Proficient Readers: percentile ranks above 45 on both Word Attack and Passage Comprehension subtests 21 Resilient Readers: percentile ranks above 45 on Passage Comprehension subtest, below 33 on Word Attack subtest 12 Poor Readers: percentile ranks below 33 on both Word Attack and Passage Comprehension subtests Structural MRI Processing Each participant received a volumetric MRI scan (3-D SPGR, 1.2 mm thick images) Tissue classification algorithm segmented gray matter, white matter, and CSF (Shattuck, et al, 201) 17 sulci in each hemisphere traced Surface warping algorithm used to drive anatomy from each individual into correspondence (Thompson, et al., 2000) Radial expansion (local brain size) and gray matter thickness calculated for each subject and compared across groups Permutation analyses to correct for multiple comparisons ResultsConclusions Dyslexic subjects show altered morphology across several cortical regions: -Inferior frontal cortex (Eckert, et al., 2003) -Temporo-parietal cortex (Brown, et al., 2001) -Inferior occipital-temporal cortex (Brambati, et al., 2004) Different cortical regions may play different roles in reading processes (Pugh, et al., 1996). Resilient readers show deficits in phonological processing, but not comprehension (Welcome, et al., 2009). -Comparisons with proficient readers allow investigation of neural substrates of phonological skill -Comparisons with poor readers allow investigation of neural substrates of comprehension skill Introduction This research was supported by NIH grant DC Resilient and poor readers, who share phonological processing deficits, show decreased asymmetry of gray matter thickness in temporo-parietal regions. -Temporo-parietal regions more active during tasks that require print-to-sound conversion (Booth, et al., 2002) Poor, but not resilient, readers show decreased radial expansion of bilateral inferior frontal regions. -Anterior portion of inferior frontal gyrus shows activation during semantic tasks (Poldrack, et al., 1999) Resilient readers show trend toward alteration of medial morphology. -Medial frontal cortex may play a role in conflict detection or error monitoring (Kiehl, et al, 2000) Phonological decoding and reading comprehension skills appear to relate to different aspects of brain morphology. Resilient readers show neuroanatomical differences from both poor readers and proficient readers, suggesting that they may represent a separate reading population. Methods References Proficient versus Poor Proficient versus Resilient versus Poor Proficient versus Poor Proficient versus Resilient versus Poor Proficient Readers (N=22) Poor Readers (N=12) Resilient Readers (N=21) GroupDifferences Word Attack Res/Poor < Pro Passage Comp Poor < Res/Pro Word Identification Poor < Res < Pro Verbal IQ Poor < Res/Pro Performance IQ NS Sex 11M, 11F 4M, 8F 13M, 8F NS Age NS SES NS Handedness Questionnaire 0.8 (2 non-RH) 0.7 (1 non-RH) 0.6 (3 non-RH) NS Poor readers have less radial expansion than proficient and resilient readers in bilateral inferior frontal regions Resilient readers do not differ from proficient readers in radial expansion Both poor and resilient readers show less leftward asymmetry of gray matter thickness in the temporo-parietal region Trends toward more leftward asymmetry of medial surface in resilient readers Booth, J. R., Burman, D. D., Meyer, J. R., Gitelman, D. R., Parrish, T. B., & Mesulam, M. M. (2002). 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