International Morphological Processing Conference (MoProc)

Spatiotemporal dynamics of morphological processing in adults with dyslexia

Jun 24, 2017, 10:50 AM

1h 55m

SISSA Park (SISSA Main Campus)

Poster Freely Contributed Paper Poster 2 (with coffee)

Speaker

Eddy Cavalli (Laboratoire de Psychologie Cognitive, Aix-Marseille Université & CNRS)

Description

Developmental dyslexia is characterized by impairments in reading fluency and spelling that persist into adulthood. Here, we hypothesized that high-achieving adult dyslexics (i.e., university students with a history of dyslexia) possibly managed to cope with these deficits by relying to a greater extent on morphological information than do non-impaired adult readers. We used magnetoencephalography (MEG) in a primed lexical decision task, in which we contrasted orthographic, morphological and semantic processing. Behavioral results confirmed that adult dyslexics did indeed rely to a greater extent on the semantic properties of morphemes than controls. In line with this, MEG results showed early morphological effects (100-200ms) in a frontal network, which reflected the contribution of semantic processing. The same effects occurred much later in controls (~400ms). In contrast, whereas controls showed early orthographic priming effects in posterior left inferior temporal gyrus at around 130ms, dyslexics showed only late activation of semantic and orthographic information in the middle left fusiform gyrus. The present results thus clearly showed morphology effects on written word recognition that were stronger and occurred earlier in high achieving adult dyslexics than in normal readers. These findings suggest a spatiotemporal reorganization of the reading network, in which higher level morphological information located in frontal regions is supposedly used in a top-down fashion to facilitate the basic bottom-up reading processes.