Top-down processes during auditory phoneme categorization in dyslexia: a PET study.

Détails

ID Serval
serval:BIB_E6FE66E098B7
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Top-down processes during auditory phoneme categorization in dyslexia: a PET study.
Périodique
Neuroimage
Auteur(s)
Dufor O., Serniclaes W., Sprenger-Charolles L., Démonet J.F.
ISSN
1053-8119 (Print)
ISSN-L
1053-8119
Statut éditorial
Publié
Date de publication
2007
Peer-reviewed
Oui
Volume
34
Numéro
4
Pages
1692-1707
Langue
anglais
Notes
Publication types: Journal Article ; Research Support, Non-U.S. Gov'tPublication Status: ppublish
Résumé
While persistence of subtle phonological deficits in dyslexic adults is well documented, deficit of categorical perception of phonemes has received little attention so far. We studied learning of phoneme categorization during an activation H(2)O(15) PET experiment in 14 dyslexic adults and 16 normal readers with similar age, handedness and performance IQ. Dyslexic subjects exhibited typical, marked impairments in reading and phoneme awareness tasks. During the PET experiment, subjects performed a discrimination task involving sine wave analogues of speech first presented as pairs of electronic sounds and, after debriefing, as syllables /ba/ and /da/. Discrimination performance and brain activation were compared between the acoustic mode and the speech mode of the task which involved physically identical stimuli; signal changes in the speech mode relative to the acoustic mode revealed the neural counterparts of phonological top-down processes that are engaged after debriefing. Although dyslexic subjects showed good abilities to learn discriminating speech sounds, their performance remained lower than those of normal readers on the discrimination task over the whole experiment. Activation observed in the speech mode in normal readers showed a strongly left-lateralized pattern involving the superior temporal, inferior parietal and inferior lateral frontal cortex. Frontal and parietal subparts of these left-sided regions were significantly more activated in the control group than in the dyslexic group. Activations in the right frontal cortex were larger in the dyslexic group than in the control group for both speech and acoustic modes relative to rest. Dyslexic subjects showed an unexpected large deactivation in the medial occipital cortex for the acoustic mode that may reflect increased effortful attention to auditory stimuli.
Mots-clé
Auditory Perception/physiology, Awareness, Brain/physiopathology, Brain/radionuclide imaging, Brain Mapping, Dyslexia/physiopathology, Humans, Language, Memory, Patient Selection, Positron-Emission Tomography/methods, Reading, Recognition (Psychology), Sound, Speech Therapy
Pubmed
Web of science
Création de la notice
24/03/2013 19:53
Dernière modification de la notice
03/03/2018 22:18
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