TY - JOUR
T1 - Reading words and pseudowords in dyslexia
T2 - ERP and behavioural tests in English-speaking adolescents
AU - Taroyan, Naira A.
AU - Nicolson, Roderick I.
N1 - Funding Information:
It is of interest to attempt to relate these findings to brain regions and, in particular, the VWFA. While modern high density sensor nets provide much better spatial resolution ( Srinivasan et al., 1998 ), it is important, however, to acknowledge the danger of attempting to infer regional activation from the scalp-located electrodes, especially for cortical regions distal from the scalp. Consequently, one must proceed with caution, looking for evidence that converges with findings from related neuroimaging (MEG and fMRI) studies. In the current study the link of left occipital electrode sites to the VWFA is supported by the ‘lexicality’ (word/pseudoword) effect, both for the early (P1) and late (P4) ERP activation, found in the occipitotemporal region only (and not in parietal, for example). Correspondence with previous ERP studies is supported by the similar timescales of the early (P1) activation peaks.
PY - 2009/12/1
Y1 - 2009/12/1
N2 - The study reports neurophysiological and behavioural correlates of lexical decision processes in English speaking dyslexic and non-dyslexic readers. Nine dyslexic adolescents (ages 15.6-17.8) and 9 control (ages 15.4-19.3) adolescents were tested, and the event related potentials (ERPs) to words and pseudowords were recorded simultaneously with behavioural measures. As expected, both groups showed significantly lower accuracy and longer response times for the pseudowords. Furthermore, overall performance (in terms of lower accuracy and longer response times) was significantly worse for the dyslexic group. The ERP analysis indicated that the later positive peaks, P4 (around 400 ms from stimulus onset) and P5 (around 500 ms), were significantly delayed and attenuated for the dyslexic group. Analysis of the early ERP peaks recorded in the occipitotemporal region led to an interesting dissociation. The controls showed a left lateralised Condition effect, with the amplitude of P1 significantly smaller to words than pseudowords. By contrast, there was no such lexical effect for the dyslexic group, with equal P1 amplitudes for words and pseudowords, at the control level for pseudowords. The deviations in the early ERP components of dyslexics support the evidence of deficits in pre-lexical visual word form recognition within the first 110 ms of activation together with altered hemispheric asymmetry. In addition, the slowed and attenuated late ERP components and weaker behavioural performance of the dyslexic group highlight deficits in the later, cognitive, processing stages.
AB - The study reports neurophysiological and behavioural correlates of lexical decision processes in English speaking dyslexic and non-dyslexic readers. Nine dyslexic adolescents (ages 15.6-17.8) and 9 control (ages 15.4-19.3) adolescents were tested, and the event related potentials (ERPs) to words and pseudowords were recorded simultaneously with behavioural measures. As expected, both groups showed significantly lower accuracy and longer response times for the pseudowords. Furthermore, overall performance (in terms of lower accuracy and longer response times) was significantly worse for the dyslexic group. The ERP analysis indicated that the later positive peaks, P4 (around 400 ms from stimulus onset) and P5 (around 500 ms), were significantly delayed and attenuated for the dyslexic group. Analysis of the early ERP peaks recorded in the occipitotemporal region led to an interesting dissociation. The controls showed a left lateralised Condition effect, with the amplitude of P1 significantly smaller to words than pseudowords. By contrast, there was no such lexical effect for the dyslexic group, with equal P1 amplitudes for words and pseudowords, at the control level for pseudowords. The deviations in the early ERP components of dyslexics support the evidence of deficits in pre-lexical visual word form recognition within the first 110 ms of activation together with altered hemispheric asymmetry. In addition, the slowed and attenuated late ERP components and weaker behavioural performance of the dyslexic group highlight deficits in the later, cognitive, processing stages.
KW - Dyslexia
KW - Event related potentials
KW - Pseudoword
KW - Reaction time
KW - Word
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U2 - 10.1016/j.ijpsycho.2009.09.001
DO - 10.1016/j.ijpsycho.2009.09.001
M3 - Article (journal)
C2 - 19747953
AN - SCOPUS:70449521104
SN - 0167-8760
VL - 74
SP - 199
EP - 208
JO - International Journal of Psychophysiology
JF - International Journal of Psychophysiology
IS - 3
ER -