Atypical lateralization to amplitude modulation in Chinese adults with reading difficulty history

Objectives: Auditory processing underlies phonological representation and presents neural oscillation lateralization in the brain. Atypical lateralization in auditory processing has been widely accepted associated with impaired reading skills in alphabetic languages. However, whether Chinese adults with reading difficulty (RD) history presents atypical lateralization in auditory processing similar to those in alphabetic languages remains unknown. The purpose of this study was to investigate whether Chinese adults with poor reading would show lateralization of neural oscillations during auditory sampling. Design: Thirty-two adults with self-report RD history and 44 adults without RD history were screened out by Chinese Adult Reading History Questionnaire (CARHQ). Reading accuracy, phonological accuracy, and rapid automatized naming (RAN) were assessed in all the participants. Auditory steady state cortical responses (ASSR) modulated at 10-80 Hz was recorded during a 6s white noise. Time-frequency power and phase synchrony indices were used to measure induced oscillatory power and synchrony of beta and gamma oscillations related to phonemic processing. Results: Adults with RD history performed worse than adults without RD history in reading accuracy and phonological accuracy. Also, adults with RD history showed atypical rightward lateralization in the gamma band, whereas the adults without RD history showed leftward lateralization. Event-related spectral perturbation (ERSP) in the left hemisphere negatively correlated with reading accuracy in adults with RD history, while left hemisphere ERSP lateralization positively correlated with phonological accuracy in adults without RD history. The inter-trial phase synchrony (ITPS) in the right hemisphere also correlated with reading accuracy in adults with RD history. Conclusions: The present study revealed auditory lateralization deficits in Chinese adults with RD history. Keywords: Reading difficulty history, Chinese adults, Auditory processing, Lateralization, Event-related spectral perturbation.