[Abstract Title]. - Society for Neuroscience

Poster
249. Dyslexia, SLI, and Other Disorders of Cognition and Behavior
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 249.6/U25
Topic: C.05.d. ADHD, SLI, dyslexia and other specific disorders of neurobehavior
Support: Eemil Aaltonen Foundation
Centre of Excellence program of Academy of Finland (44858 and 213486)
Title: Training with speech sounds affects electric brain responses of dyslexic children
Authors: *P. H. LEPPANEN 1 , S. TUOVINEN 1 , J. HAMALAINEN 2 , A. TANSKANEN 1 , A.
OKSANEN 1 , K. LOHVANSUU 1 ;
1 Dept Psychol, Univ. Jyvaskyla, Jyvaskyla, Finland; 2 Ctr. for Neurosci. in Educ., Univ. of
Cambridge, Cambridge, United Kingdom
Abstract: Dyslexia, impairment in learning to read, is faced by 5-10 percent of population. In a
sub-group of dyslexic children, an underlying problem is suggested to be related to speech
perception and phonemic representations, which in turn affect grapheme-phoneme conversion
ability. Here we studied, using auditory brain event-related potentials (ERPs), how combined
training of low level perceptual skills (bottom-up processing) followed by training of higher
level skills of linking speech sounds to letters (top-down processing) would affect speech
processing in 9-10 year-old dyslexic children. The focus in speech perception training was in
temporal differences. Combined training group (N=10) received speech perception training
which was followed by grapheme-phoneme training. G-P-only training group (N=9) received
grapheme-phoneme training only. Matched control group (N=10) attended only to regular school
based educational program and did not receive any training. Training effects were examined
from the ERPs before and after training periods. Naturally produced pseudoword stimuli with
varying stop consonant durations (ata and atta, with silent gaps of 95 ms and 255 ms,
respectively) were presented in a passive oddball paradigm with an interstimulus-interval of 610
ms. The analyses of current source density maps of the N250 response at about 250 ms after the
initial vowel or second syllable onset revealed training effects. N250 for the initial /a/-vowel
(followed with both short and long stop consonants) showed larger increase in the area involving
negative fronto-central activation in the post-training measurement in Combined training group
than in the other two groups. The same pattern was observed also for the second syllable /ta/
following the short gap. This topographical pattern is in line with studies showing that N250
shifts towards fronto-central distribution with maturation in typical readers. The ERP related to
the differentiation between short and long /t/-duration (in ata vs. atta) showed larger area changes
in both training groups in comparison to Matched control group. The results thus showed
training effects on basic auditory processing, manifested in changes of brain responses to the
stimulus onset, and on rapid rate auditory processing (of the second syllable onset following a