Lay summary
Aims: Developmental dyslexia, a specific reading disorder, affects 5-10% of the school children. Although diagnosed as a failure of learning to read in childhood, dyslexia often persists into adulthood, and contributes significantly to the high prevalence of illiteracy. Brain imaging has revealed a major role of reduced coarse visual tuning for print in dyslexic children [1, 2], but whether this persists in adults with dyslexia remains open. Here, we examine visual print processing in adolescents and adults, using functional brain mapping with EEG (Electroencephalogram) and fMRI (functional magnetic resonance imaging). A first core question is whether visual print tuning remains impaired in older, persistently dyslexic readers under realistic reading conditions. A second core question is whether behavioural and brain markers from kindergarten can predict persistent dyslexia in our longitudinal sample [3], and how print tuning changes during late development.Context and impact: The study will clarify how illiteracy in adulthood relates to dyslexia as typically diagnosed in childhood. The study will further clarify the role of visual tuning deficits for dyslexia beyond school age. How such impaired brain processes develop is of practical relevance for conceptualizing age-appropriate training programs for dyslexia. Methods: Adolescents who already participated in our longitudinal study in kindergarten, 2nd grade and 5th grade are followed up in 9th grade. Reading and spelling abilities are assessed first. During simultaneous EEG-fMRI recordings, participants then perform additional reading tests engaging brain mechanisms specialized for processing print. To increase group sizes, additional dyslexic and non-dyslexic adolescents who participated only in 5th grade are also invited. The same protocol will also be run with groups of dyslexic and non-dyslexic adults.1) Maurer, U., Brem, S., Bucher, K., Kranz, F., Benz, R., Halder, P., Steinhausen, H.-C., & Brandeis, D. (2007). Impaired tuning of a fast occipito-temporal response to print in dyslexic children learning to read. Brain, 130, 3200-3210.2) Van der Mark, S., Bucher, K., Maurer, U., Schulz, E., Brem, S., Buckelmüller, J., Kronbichler, M., Loenneker, T., Klaver, P., Martin, E., & Brandeis, D. (in press). Dyslexia in children: dysfunction of specialization within the Visual Word-Form (VWF) system. Neuroimage.3) Maurer, U., Bucher, K., Brem, S., Benz R., Kranz, F., Schulz, E., van der Mark, S., Steinhausen, H.-C., Brandeis, D. (2009). Neurophysiology in preschool improves behavioral prediction of reading ability throughout primary school. Biological Psychiatry, 66, 341-348.