title: Out-of-synchrony speech entrainment in developmental dyslexia.
abstract: Developmental dyslexia is a reading disorder often characterized by reduced awareness of speech units. Whether the neural source of this phonological disorder in dyslexic readers results from the malfunctioning of the primary auditory system or damaged feedback communication between higher-order phonological regions (i.e., left inferior frontal regions) and the auditory cortex is still under dispute. Here we recorded magnetoencephalographic (MEG) signals from 20 dyslexic readers and 20 age-matched controls while they were listening to ∼10-s-long spoken sentences. Compared to controls, dyslexic readers had (1) an impaired neural entrainment to speech in the delta band (0.5-1 Hz); (2) a reduced delta synchronization in both the right auditory cortex and the left inferior frontal gyrus; and (3) an impaired feedforward functional coupling between neural oscillations in the right auditory cortex and the left inferior frontal regions. This shows that during speech listening, individuals with developmental dyslexia present reduced neural synchrony to low-frequency speech oscillations in primary auditory regions that hinders higher-order speech processing steps. The present findings, thus, strengthen proposals assuming that improper low-frequency acoustic entrainment affects speech sampling. This low speech-brain synchronization has the strong potential to cause severe consequences for both phonological and reading skills. Interestingly, the reduced speech-brain synchronization in dyslexic readers compared to normal readers (and its higher-order consequences across the speech processing network) appears preserved through the development from childhood to adulthood. Thus, the evaluation of speech-brain synchronization could possibly serve as a diagnostic tool for early detection of children at risk of dyslexia. Hum Brain Mapp 37:2767-2783, 2016. © 2016 Wiley Periodicals, Inc.
authors.affiliation: BCBL, Basque Center on Cognition, Brain and Language, San Sebastian, Spain.|Ikerbasque, Basque Foundation for Science, Bilbao, Spain.
authors.forename: Nicola
authors.initials: N
authors.lastname: Molinaro
authors.affiliation: BCBL, Basque Center on Cognition, Brain and Language, San Sebastian, Spain.
authors.forename: Mikel
authors.initials: M
authors.lastname: Lizarazu
authors.affiliation: BCBL, Basque Center on Cognition, Brain and Language, San Sebastian, Spain.
authors.forename: Marie
authors.initials: M
authors.lastname: Lallier
authors.affiliation: BCBL, Basque Center on Cognition, Brain and Language, San Sebastian, Spain.|Department of Neuroscience and Biomedical Engineering, Aalto University School of Science, Espoo, Finland.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Bourguignon
authors.affiliation: BCBL, Basque Center on Cognition, Brain and Language, San Sebastian, Spain.|Ikerbasque, Basque Foundation for Science, Bilbao, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Carreiras
mesh_terms: D000328:Adult; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D004410:Dyslexia / Q000503:physiopathology*; D005260:Female; D006801:Humans; D015225:Magnetoencephalography; D008297:Male; D013067:Speech Perception / Q000502:physiology*; D055815:Young Adult
keywords: auditory entrainment; developmental dislexia; effective connectivity; magnetoencephalography; speech perception