title: Multimodal lexical processing in auditory cortex is literacy skill dependent.
abstract: Literacy is a uniquely human cross-modal cognitive process wherein visual orthographic representations become associated with auditory phonological representations through experience. Developmental studies provide insight into how experience-dependent changes in brain organization influence phonological processing as a function of literacy. Previous investigations show a synchrony-dependent influence of letter presentation on individual phoneme processing in superior temporal sulcus; others demonstrate recruitment of primary and associative auditory cortex during cross-modal processing. We sought to determine whether brain regions supporting phonological processing of larger lexical units (monosyllabic words) over larger time windows is sensitive to cross-modal information, and whether such effects are literacy dependent. Twenty-two children (age 8-14 years) made rhyming judgments for sequentially presented word and pseudoword pairs presented either unimodally (auditory- or visual-only) or cross-modally (audiovisual). Regression analyses examined the relationship between literacy and congruency effects (overlapping orthography and phonology vs. overlapping phonology-only). We extend previous findings by showing that higher literacy is correlated with greater congruency effects in auditory cortex (i.e., planum temporale) only for cross-modal processing. These skill effects were specific to known words and occurred over a large time window, suggesting that multimodal integration in posterior auditory cortex is critical for fluent reading.
authors.affiliation: Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL 60208, USA.
authors.forename: Chris
authors.initials: C
authors.lastname: McNorgan
authors.affiliation: Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL 60208, USA.
authors.forename: Neha
authors.initials: N
authors.lastname: Awati
authors.affiliation: Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL 60208, USA.
authors.forename: Amy S
authors.initials: AS
authors.lastname: Desroches
authors.affiliation: Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL 60208, USA.
authors.forename: James R
authors.initials: JR
authors.lastname: Booth
mesh_terms: D000293:Adolescent; D001303:Auditory Cortex / Q000254:growth & development / Q000502:physiology*; D002648:Child; D005260:Female; D006801:Humans; D007600:Judgment / Q000502:physiology; D007804:Language Development; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010700:Phonetics; D011932:Reading; D013061:Speech Acoustics; D013067:Speech Perception / Q000502:physiology*
keywords: audiovisual integration; cross-modal; development; fMRI; reading