Behavioural and Physiological Measures of Young Students With Dyslexia

A learning disability in reading is one of the most common neurobiological diagnoses in school-aged children. Statistics Canada reported that 3.2% of children in Canada have a learning disability (LD), making LD the most prevalent type of childhood condition. The new definition of LD has become more complicated to diagnose and treat children. Canadian universities invested recently in conducting research that tracks neural changes in the identification and remediation of LD. Electroencephalography (EEG) is one of the most common tools to inquire about brain information processing and neural changes. However, only one German study has used a reading intervention and EEG to track neural changes of children with LD in reading. This study delivered two reading interventions but did not report which intervention affected reading improvement. Hence, little is known about reading interventions that would induce positive neural changes in young children with LD. This proposal aims to implement a specific reading intervention in children and track neuronal changes. The results of this proposal will be invaluable in improving the predictive tools we use for early diagnosis of LD in reading, identifying better-targeted reading interventions, and in better allocation of resources to health and educational services.

To understand how the brain processes language in real-time, Event-Related Potential (ERPs) studies have been commonly used to assess the neural underpinnings of reading disability (RD), especially in children. Of particular interest, the N400 is a negative ERP waveform peaking at 400 milliseconds that is sensitive to the lexico-semantic aspect of language. The N400 represents an important language-relevant measure that can be used to investigate the neural basis of reading comprehension acquisition in typical readers, a process critical to reading development in school-age populations. The N400 assesses lexical-semantic processing when a student is introduced to a sentence with a pseudoword or a semantically incorrect word, as in "the pizza was too hot to cry." The N400 is sensitive in typical readers, indicating that they understand the semantic incongruity. There is also evidence that the N400 is atypical in individuals with reading disabilities and reading comprehension deficits.

These brain-based explanations give educational practice and understanding of the neural processes underlying reading difficulties, reading comprehension deficits, and potentially effective intervention mechanisms. Several studies demonstrate the potential relevance of neuroimaging for identifying a reading disability. Researchers have also shown that neural changes occur after a successful reading intervention. However, it remains unknown whether a reading intervention modulates reading-relevant brain activity, such as that of the N400.

One common approach to this problem is to teach common exception words by sight. An alternative approach some researchers have proposed is that in addition to teaching phonics, children are to be trained to "generate alternative pronunciations when they come to unknown words until they produce a pronunciation that is a real word, and which makes sense in context". This process is known as Set-for-Variability (SfV). For example, a child is taught the standard pronunciation of "ch" in the match, hatch, and catch. The child would then use this regularized pronunciation of "ch" to read the word stomach, an irregular spelled word. If a child fails to read the irregularly spelled word stomach using regularized pronunciation, then "the child has to change one or more sound associations and try again". Set-for-Variability is "the ability to determine the correct pronunciation of proximation to spoken English words". This means making a link from 'spelling pronunciations' (the product of synthetic phonics such as 'c'-'a'-'t' from the printed word 'cat') to a conventional pronunciation of that word. If pronouncing a word does not produce a meaningful phrase in context, the individual would need to try a different pronunciation.

The proposed study is a randomized-control study where thirty-eight students aged 6-7 years with a reading disability will be randomly assigned into a control and intervention group. The participants will be matched on age, IQ, and reading level before randomization. Participants in the control group will be included in a Current Best Practices (CBP) group and exposed to an intervention that focuses on grapheme-phoneme correspondence rules. In addition to the CBP, participants in the intervention group will receive 8-10 weeks of the Set-for-Variability intervention. Pre-post behavioural measures will be conducted to see if the Set-for-Variability intervention impacts word reading measured using validated assessment tools and the N400 amplitude. The present research will provide the first empirical data on the neural changes following a "Set-for-Variability"-based reading intervention.