Neural tuning of the reading system

San Diego State University Foundation, San Diego CA

Investigators

Abstract

Reading is a skill that is critical for our social, educational, and political lives, and yet we know relatively little about how our brain becomes "tuned" to written words. Many theories propose that reading builds upon speech perception and that the quality of phonological representations -- that is, those related to how words sound -- plays a central role in how the brain responds to printed words. Skilled readers who are congenitally and profoundly deaf pose a challenge to these models because they do not have rich phonological representations of speech. This project investigates word reading processes in deaf and hearing adults who have similar reading abilities. Its main aim is to understand whether brain areas involved in reading are impacted by differences in phonological knowledge and auditory experience. Electroencephalography (EEG) and innovative statistical analyses will be used to determine how the timing of the brain's response to words is influenced by deafness and reading skill. Functional Magnetic Resonance Imaging (fMRI) will also be used to characterize how brain regions previously linked to word-reading respond for deaf and hearing readers. In addition, this project aims to promote the participation of deaf people in research by providing an environment that is accessible to them (e.g., "deaf friendly" labs) and training that facilitates academic advancement. The principal investigators (Drs. Karen Emmorey and Phillip Holcomb) are committed to improving opportunities for deaf students. This project contains six studies that use neural tuning paradigms to identify the stimulus-based and experience-based factors that shape the brain's response to orthographic stimuli. Two event-related potential (ERP) studies investigate the "fine tuning" of different neural responses (e.g., N/P170, N270) across several levels of representation (e.g., words, pseudowords, consonant strings, pseudo-letter strings). Using linear mixed effects (LME) analyses these experiments examine how individual variation in specific linguistic skills modulate these ERP components. Two fMRI studies parallel these ERP studies but capitalize on the strengths of fMRI paradigms to reveal functional and spatial organization within the reading circuit. A third ERP study tests the distinction proposed by the Bimodal Interactive Activation Model (BIAM) between the N400w and N400c ERP responses (exploiting differences between deaf and hearing participants with respect to implicit picture naming). The final study examines whether differences in visual peripheral attention between deaf and hearing individuals impact neural tuning to letters (using a visual crowding paradigm). By addressing basic science questions about the flexibility of the reading circuit, this project will provide foundational evidence for developing reading interventions and improving reading acquisition for both deaf and hearing people. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.