Author:
Gudwani Sunita,Mehta Manju,Sagar Rajesh,Behari Madhuri,Narang Vaishna,Dwivedi Sadanad,Jagannathan N.R.,Kumaran S. Senthil
Abstract
AbstractReading creates accessibility to the outer world information and is an integral skill for academic achievement. It involves visual perception, reasoning at symbolic level (text reading) and phonological processing. But does perception, visuospatial processing at pre-symbolic level affect reading skill? To understand and untangle the mechanism fifty children with reading problem (developmental dyslexia, DDC) and twentyfive age-matched typical readers (healthy controls, HC) were studied. In DDC, the variable-performance of non-symbolic visual search (pictorial-level) was associated with bilateral brain activity (functional MRI) of ventral stream (inferior occipital and fusiform) and greater involvement of frontal-prefrontal regions, suggesting the modified dorsal route-gating for figure-ground filtering. Performance variability in picture-concept reasoning (71.9% and significant group mean difference) and visuospatial-organization (51.3%) of DDC children indicate attentional or executive differences at nonsymbolic level. In symbolic discrimination performance, no significant difference observed for single alphabet or number (digit) reading but significant differences at word level for visual and phonological performance (considering orthographic differences), attributes to distractor-inhibition problems. Nonsymbolic to symbolic coding/decoding speed and writing error (copying) differences are suggestive of execution variability rather than motor coordination in DDC. In HC, the top-down dorsal route gating and hypoactivity induced in right frontal-anterior cingulate cortices, play a major role in reading by allocating spatial attention and inhibiting distractors. It has been elaborated in the “neurobiological model”.How perception and attention participate in reading skill?Research HighlightsVisuospatial attention, executive control (nonsymbolic level) and visual discrimination (symbolic level) performance contribute to reading.In children with reading problems (dyslexia) pictorial visual processing task (fMRI) recruited higher activation in right hemispheric frontal, inferior parietal and anterior cingulate regions.Bilateral activation of occipital-striate, extra-striate, fusiform for nonsymbolic is associated with significantly more errors at bigger-symbol-string, in dyslexia.Auditory discrimination differences in shallow-deep orthography.Correlation of non-symbolic executive and symbolic performances.Role of the prelexical visual perception and dorsal-route gating in reading skill explained as neurobiological model.
Publisher
Cold Spring Harbor Laboratory