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Is there an auditory discrimination defect in dyslexia? A study using time-frequency analysis of mismatch responses of Chinese children

Poster D45 in Poster Session D, Wednesday, October 25, 4:45 - 6:30 pm CEST, Espace Vieux-Port

Jiaru Tang¹, Yaowen Liang¹, Chenlu Fu¹, Zihan Yang¹, Yiwei Zhao¹, Xiujie Yang*¹, Hua Shu*¹; ¹Beijing Normal University

Introduction: Developmental dyslexia is a neurodevelopmental disorder characterized by a notable delay in reading ability. This delay is primarily attributed to a phonological deficit, as suggested by prevailing theories. Mismatch Negativity (MMN) is a highly sensitive indicator of automatic auditory information processing and can be utilized to identify neural abnormalities in children with dyslexia. However, there is limited research available on dyslexia that investigates the time-frequency information within MMN. Additionally, there is a lack of research specifically focused on dyslexia within Chinese, which is a non-alphabetic language featuring four different tones at the suprasegmental level. The objective of our study is twofold: (1) To determine whether significant differences exist in the time-frequency information processing of MMN between dyslexic children and non-dyslexic children; (2) To explore how the neural representation of auditory features in Chinese-speaking children is influenced by reading-related cognitive abilities, subsequently impacting reading performance. Method: The study involved 22 Chinese children aged 8 to 14, comprising 18 Developmental Dyslexic (DD) children and 6 Non-Dyslexic (ND) children. We assessed their reading-related cognitive abilities. Then the children instructed to ignore the presented sounds through the air tube headsets while watching a silent cartoon. Lexical tone pairs and consonant pairs were played in two separate experiment sessions. The tone pairs session presented /ji1/ as a standard and /ji4/ as a deviant; the consonant pairs presented /ta1/ as a standard and /ba1/ as a deviant. We used MNE to do EEG data processing and run time-frequency analysis to obtain the ITC of MMN. The frequency range was specified as 4–7 Hz (theta range), electrodes of ‘Fz’ ‘F3’ ‘F4’ were chosen, and the time window was 320-390ms. The independent samples t-test was conducted between DD and ND using ITC index as the dependent variable. The correlation between the ITC and reading-related cognitive tests was calculated, and the mediation model was constructed using the PROCESS plugin in SPSS 26.0. Results: The results of the t-test revealed that, in the tone pairs condition, the DD group exhibited significantly higher Inter-Trial Coherence (ITC) compared to the ND group (t = -2.14, p = 0.04) during standard stimulus trials. Additionally, the ITC index, specifically under the tone pairs condition, exhibited a negative correlation with test scores of Character Recognition, Three-minute Speed Reading, and Phenome Deletion. The findings from the mediation model indicated that ITC, under the tone pairs condition, indirectly influences Three-minute Speed Reading through the mediator Phenome Deletion Task. Furthermore, the direct effect of ITC on Three-minute Speed Reading was found to be insignificant, suggesting that Onset Deletion Task serves as a complete mediator. Conclusion: Our findings revealed an enhanced ITC in the theta frequency band over the MMN time window. These findings shed light on the neurophysiological processes involved in auditory discrimination between children with developmental dyslexia and non-dyslexic children, particularly within the context of a non-alphabetic language. Additionally, our study confirmed the significant impact of phonological perception on phonological awareness, which in turn contributes to children's reading performance.

Topic Areas: Disorders: Developmental, Phonology