Effects of stimulus difficulty and repetition on printed word identification: an fMRI comparison of nonimpaired and reading-disabled adolescent cohorts.
Functional neuroimaging studies indicate that a primary marker of specific reading disability (RD) is reduced activation of left hemisphere (LH) posterior regions during performance of reading tasks. However, the severity of this disruption, and the extent to which these LH systems might be available for reading under any circumstances, is unclear at present. Experiment 1 examined the cortical effects of stimulus manipulations (frequency, imageability, consistency) that have known facilitative effects on reading performance for both nonimpaired (NI) and RD readers. Experiment 2 examined stimulus repetition, another facilitative variable, in an additional sample of adolescent NI and RD readers. For NI readers, factors that made words easier to process were associated with relatively reduced activation. For RD readers, facilitative factors resulted in increased activation in these same reading-related sites, suggesting that the LH reading circuitry in adolescent RD is poorly trained but not wholly disrupted.
Pugh
Kenneth R
KR
Haskins Laboratories, New Haven, CT 06511, USA. pugh@haskins.yale.edu
Frost
Stephen J
SJ
Sandak
Rebecca
R
Landi
Nicole
N
Rueckl
Jay G
JG
Constable
R Todd
RT
Seidenberg
Mark S
MS
Fulbright
Robert K
RK
Katz
Leonard
L
Mencl
W Einar
WE
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000098:blood supply* / Q000473:pathology / Q000503:physiopathology; D002648:Child; D015331:Cohort Studies; D004410:Dyslexia / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007062:Identification, Psychological; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D010100:Oxygen / Q000097:blood; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time / Q000502:physiology; D014825:Vocabulary
D010100:Oxygen