Authors: Shelley Shaul, Yossi Arzouan, Abraham Goldstein.
Publication: International Journal of Psychophysiology (Elsevier). Volume 84, Issue 3, Pages 270-276 2012 | DOI: 10.1016/j.ijpsycho.2012.03.005
► We examine processing of words and pseudo words among dyslexic and regular readers. ► We use behavioral and electrophysiological and source estimation measures. ► Differences were found in hemispheric activity. ► Dyslexic readers show a similar pattern of activation for words and pseudo words.
In recent years many studies have focused on brain activity differences between fluent and dyslexic readers in order to understand the neural basis of dyslexia. The aim of the current study was to examine the processing of words and pseudo-words in the two hemispheres among dyslexic as compared to fluent readers, using behavioral, and electrophysiological source estimation measures. Two matched groups of university students, fluent and dyslexic readers, performed a lexical decision task in order to examine the processes of word recognition. Dyslexic readers showed overall less activity than fluent readers, mainly during late processing stages. In addition, the distinctive patterns of activity for words and pseudo-words displayed by fluent readers were not apparent in dyslexic readers. In particular, the increased activation of left-hemisphere language areas found in response to pseudo-words was absent in dyslexics. These findings are further evidence of orthographic and phonological impairments in dyslexia.
Shaul, S., Arzouan, Y., & Goldstein, A. (2012). Brain activity while reading words and pseudo-words: a comparison between dyslexic and fluent readers. International journal of psychophysiology : official journal of the International Organization of Psychophysiology, 84(3), 270–276. https://doi.org/10.1016/j.ijpsycho.2012.03.005
The current study investigated the time course of hemispheric activity while processing words and pseudo-words among dyslexic as compared to ﬂuent readers. The lexical decision task used is indicativeof orthographic-semantic processing (words) and phonological processing (pseudo-words), both basic cognitive skills needed for reading.
The subjects in this study were ‘compensated’ adult dyslexics and a control group of age-matched ﬂuent readers.
Whereas dyslexics displayed greater activity during the early stage (~200 ms) relative to later ones, ﬂuent readers showed the opposite pattern. This may indicate that compensated dyslexic readers rely mainly on orthographic–visual processing during the lexical decision task, and allocate less resources to the later evaluation and decision stages….
In addition, ﬂuent readers exhibited differential responses towords and pseudo-words, but brain responses of dyslexic readers were not sensitive to this property and showed comparable responses to both words and pseudo-words.
More interestingly, the distinctive responses to words and pseudo-words were manifested as differential activation of the left and right hemispheres. At a global-hemispheric level, group differences between ﬂuent and dyslexic readers were most prominent during the 500–700 ms interval.