title: Neural substrates of impaired categorical perception of phonemes in adult dyslexics: an fMRI study.
abstract: Phonological developmental dyslexics remain impaired in phonetic categorical perception (CP) even in adulthood. We studied the brain correlates of CP in dyslexics and controls using a block design fMRI protocol and stimuli from an phonetic continuum between natural /Pa/ and /Ta/ syllables. Subjects performed a pseudo-passive listening task which does not imply voluntary categorical judgment. In the control group, categorical deviant stimuli elicited specific activations in the left angular gyrus, the right inferior frontal gyrus and the right superior cingulate cortex. These regions were not activated in the dyslexic group in which activation was observed for acoustic but not phonetic changes in stimuli. Failures to activate key regions for language perception and auditory attention in dyslexic might account for persistent deficits in phonological awareness and reading tasks.
authors: INSERM, U. 455, Toulouse, France.
authors: Serge
authors: S
authors: Ruff
authors: Nathalie
authors: N
authors: Marie
authors: Pierre
authors: P
authors: Celsis
authors: Dominique
authors: D
authors: Cardebat
authors: Jean-François
authors: JF
authors: Démonet
mesh_terms: D000328:Adult; D001288:Attention; D001303:Auditory Cortex / Q000378:metabolism*; D001364:Awareness; D004410:Dyslexia / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D010700:Phonetics; D013067:Speech Perception