Left premotor cortex and allophonic speech perception in dyslexia: a PET study.

Détails

ID Serval
serval:BIB_3A17859CF99D
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Left premotor cortex and allophonic speech perception in dyslexia: a PET study.
Périodique
Neuroimage
Auteur(s)
Dufor O., Serniclaes W., Sprenger-Charolles L., Démonet J.F.
ISSN
1095-9572 (Electronic)
ISSN-L
1053-8119
Statut éditorial
Publié
Date de publication
2009
Peer-reviewed
Oui
Volume
46
Numéro
1
Pages
241-248
Langue
anglais
Notes
Publication types: Journal Article ; Research Support, Non-U.S. Gov'tPublication Status: ppublish
Résumé
Disorders of categorical perception has been put forward as a new account of phonological deficit in dyslexia (Serniclaes, W., Sprenger-Charolles, L., Carre, R. and Demonet, J.F., 2001. Perceptual discrimination of speech sounds in developmental dyslexia. J. Speech Lang. Hear. Res. 44, 384-399.) so that dyslexic subjects tend to discriminate phoneme instances within a given phonemic category rather than between categories, possibly witnessing the persistence of phonemic boundaries of 'allophones' that may be relevant to other languages although not to one's mother tongue (Serniclaes, W., Van Heghe, S., Mousty, P., Carre, R. and Sprenger-Charolles, L., 2004. Allophonic mode of speech perception in dyslexia. J. Exp. Child Psychol. 87, 336-361.). The brain correlates of within- and between-category discrimination were explored using a /ba/-/da/ phonetic continuum and H(2)(15)O PET in 14 dyslexic and 16 control adult readers; subjects discriminated a set of stimuli pairs, first in a 'naïve' (acoustic) condition and, after debriefing about the stimuli identity, in a speech (phonemic) condition (Dufor, O., Serniclaes, W., Sprenger-Charolles, L. and Demonet, J.F., 2007. Top-down processes during auditory phoneme categorization in dyslexia: a PET study. NeuroImage 34, 1692-1707.). While discrimination of 'between' pairs improved in all subjects following debriefing, 'within' stimuli yielded variable performance; some subjects kept discriminating them, while best categorizers judged them identical. Correlation analyses between acoustic-to-speech changes in brain activity and in 'within'-pair discrimination, and between control and dyslexic groups, revealed a criss-crossed correlation pattern in the left BA6 so that the higher the activity the better the categorization in control subjects whereas the higher the activity the more increased 'within' discrimination in dyslexic subjects. Therefore, in average readers, enhanced activity in the left BA6 likely contributes to optimizing phoneme categorization via refined speech motor coding. In dyslexic subjects showing sensitivity to 'within'-category cues, activity enhancement in this region might suggest the persistence of motor coding for allophonic representations of speech.
Mots-clé
Adult, Brain/radionuclide imaging, Dyslexia/radionuclide imaging, Female, Humans, Image Interpretation, Computer-Assisted, Magnetic Resonance Imaging, Male, Positron-Emission Tomography, Speech Perception/physiology
Pubmed
Web of science
Création de la notice
24/03/2013 20:18
Dernière modification de la notice
20/08/2019 14:29
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