[TS-2.1] The manifestation of visual attention span deficit in English-speakers with compensated dyslexia: A fMRI study

Wydell, T. & Fern-Pollak, L.

Centre for Cognition and NeuroImaging, Brunel University

This study examines the neural correlates of visual attention span (VAS) in native English-speaking university students with compensated dyslexia and their controls, using fMRI. Previous fMRI studies with French-speaking children and adults conducted by Valdois and her colleagues have shown the importance of VAS in skilled reading, where the neural correlates of VAS were associated with activation in the left superior and inferior parietal cortex. Valdois?s team further reported that reduced activation has been observed in these regions in French dyslexics with VAS disorder. In this study, native English university students and graduates performed a visual letter/shape categorisation task previously used with French participants. Similar to previous behavioural findings, these dyslexics were significantly slower in performing the task, but similarly accurate as the controls. Moreover under fMRI both groups activated the left inferior and superior parietal cortex. However, these compensated dyslexics showed greater activation relative to controls within the parietal cortex, and further revealed activation within bilateral frontal and occipito-temporal regions which were not seen in the controls. This *uneconomical* use of neural resources may underlie compensatory strategies used by these English dyslexics, in order to perform the task as accurately as controls, albeit considerably slower.