Dyslexia
Friday, September 30th, 2011 [17:20 - 19:20]
PS_1.121 - Common brain regions for behavioral predictors of reading (dis)ability
Frost, S. 1 , Landi, N. 1, 2 , Preston, J. 1 , Mencl, W. E. 1 , Fulbright, R. 2 & Pugh, K. R. 1, 2
1 Haskins Laboratories
2 Yale University
Many studies have examined the specific neurobiological signatures of the major predictors of reading dis(ability), including phonological awareness (PA), print decoding, and rapid auditory processing. Rather than focus on their unique signatures, we explored the core common brain regions associated with these reading predictors in a large cohort of emergent readers ranging on a continuum from RD to superior readers. To accomplish this, we correlated behavioral indices of each skill with functional activation for speech and print and then performed a conjunction analysis to examine the intersection of the neurobiological correlates. The conjunction analysis revealed that individual differences in PA, print decoding, and rapid auditory processing were each positively correlated with print-related activation at canonical reading-related LH neo-cortical areas (including LH superior temporal and LH angular gyri) as well as with sub-cortical loci (specifically, posterior aspects of thalamus centered in and around pulvinar). We suggest that the correlation of each of these measures with common brain regions highlights both the importance of these regions for reading the need to more fully consider the role of sub-cortical sites and their interactions with neo-cortex in reading development.
PS_1.122 - Involvement of ventral and dorsal pathways in visual word recognition in adults with developmental dyslexia: an ERP study
Mahe, G. , Bonnefond, A. & Doignon-Camus, N.
CNRS, University of Strasbourg, Strasbourg, France
The efficiency of visual word recognition relies on fast and parallel processing of letters involving the ventral visual pathway. However, words displayed in unfamiliar visual format require to be read serially under supervision of the dorsal visual pathway. The present ERP study investigated the involvement and the interactions of the ventral and dorsal visual pathways in adults with developmental dyslexia. Developmental dyslexia is a specific learning disability affecting reading acquisition. The involvement of the ventral visual system was assessed in a lexical decision task with stimuli (i.e., high and low frequency words, pseudowords or consonant strings) presented in a familiar visual format (i.e., horizontal). Same stimuli presented in an unfamiliar visual format (i.e., vertical) were used to investigate the involvement of the dorsal visual pathway. According to a visuo-spatial attention deficit hypothesis in developmental dyslexia, we expected an alteration of the dorsal pathway contribution in terms of impairment and/or delay when letter strings are presented in an unfamiliar visual format. Analysis of potential differences between dyslexics and normal readers could help us to understand the nature of their core deficit.
PS_1.123 - Spoken word recognition in normative and reading-disabled children
Cameirão, M. & Vicente, S.
Faculty of Psychology and Education - University of Porto
Spoken word recognition in normative and reading-disabled children
The Lexical Reestructuring Model (LRM; Metsala & Walley, 1998) suggests that, in young children, phonological representations are stored in the mental lexicon in a holistic fashion and, through childhood, they become increasingly segmental. The model proposes that reading-disabled (RD) children show a delay in this restructuring, which causes impairments in reading, phonological awareness and spoken word recognition tasks. We tested 17 RD children (M Age = 10.09), 17 age-matched controls (CA; M = 10.32) and 17 reading-age matched controls (RA; M = 7.72) in a gating task. The children should recognize 49 dyssilabic words, that contrasted in frequency, age-of-acquisition (AoA) and neighborhood density. The first gate of each word had 100 ms and subsequent gates increased in 50 ms. Overall, RD children needed more time than CA children to recognize words (456 vs. 429 ms), but didn´t differ significantly from the RA group (456 vs. 461, respectivily). There was a significant triple interaction between group, AoA and neighborhood density. RD children were impaired in recognizing early-acquired sparse words, but again didn´t differ from the RA group. These results puzzle the question whether imature representations are cause or consequence of poor reading experience.