Neural substrates related to auditory working memory comparisons in dyslexia: an fMRI study.
Adult readers with developmental phonological dyslexia exhibit significant difficulty comparing pseudowords and pure tones in auditory working memory (AWM). This suggests deficient AWM skills for adults diagnosed with dyslexia. Despite behavioral differences, it is unknown whether neural substrates of AWM differ between adults diagnosed with dyslexia and normal readers. Prior neuroimaging of adults diagnosed with dyslexia and normal readers, and post-mortem findings of neural structural anomalies in adults diagnosed with dyslexia support the hypothesis of atypical neural activity in temporoparietal and inferior frontal regions during AWM tasks in adults diagnosed with dyslexia. We used fMRI during two binaural AWM tasks (pseudowords or pure tones comparisons) in adults diagnosed with dyslexia (n = 11) and normal readers (n = 11). For both AWM tasks, adults diagnosed with dyslexia exhibited greater activity in left posterior superior temporal (BA 22) and inferior parietal regions (BA 40) than normal readers. Comparing neural activity between groups and between stimuli contrasts (pseudowords vs. tones), adults diagnosed with dyslexia showed greater primary auditory cortex activity (BA 42; tones > pseudowords) than normal readers. Thus, greater activity in primary auditory, posterior superior temporal, and inferior parietal cortices during linguistic and non-linguistic AWM tasks for adults diagnosed with dyslexia compared to normal readers indicate differences in neural substrates of AWM comparison tasks.
Conway
Tim
T
Department of Veterans Affairs Rehabilitation Research and Development Brain Rehabilitation Research Center of Excellence, Malcom Randall Veterans Administration Medical Center, Gainesville, Florida, USA. twc@phhp.ufl.edu
Heilman
Kenneth M
KM
Gopinath
Kaundinya
K
Peck
Kyung
K
Bauer
Russell
R
Briggs
Richard W
RW
Torgesen
Joseph K
JK
Crosson
Bruce
B
D000328:Adult; D001303:Auditory Cortex / Q000503:physiopathology*; D001931:Brain Mapping; D004292:Dominance, Cerebral / Q000502:physiology*; D004410:Dyslexia / Q000503:physiopathology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D008875:Middle Aged; D010296:Parietal Lobe / Q000503:physiopathology*; D010898:Pitch Perception / Q000502:physiology*; D013067:Speech Perception / Q000502:physiology*; D013702:Temporal Lobe / Q000503:physiopathology*