Testverfah - Bundesverband Legasthenie und Dyskalkulie eV

Abstractband 15. Kongress des Bundesverbandes Legasthenie
Richter, B. (2003). Deutsches Handbuch zum Programm AUDILEX. http://www.
paedboutique.de/frameset_audilex.htm, 26.04.2005.
Korrespondenzautor:
Jörg Reichert
joerg.reichert@rz.hu-berlin.de
++49 030 20934427
++49 030 20934435
Sensory processing in dyslexia
*Hanna Renvall
Helsinki University of Technology, Brain Research Unit, Low Temperature Laboratory, Helsinki,
Finnland
Dyslexic individuals encounter difficulties that often extend beyond the skills directly
needed for reading: for example, language-learning-impaired children are slow
in processing sounds presented in rapid succession or containing fast frequency
transitions. These auditory deficits, at a time scale of up to a few hundreds of milliseconds,
persist to adult age. Recent behavioral studies have implied that dyslexic
subjects have temporal processing deficits in other sensory modalities as well.
We have applied magnetoencephalography (MEG) and psychophysics to characterize
the temporal impairments in auditory, tactile and visual domains in dyslexic
adults. Our results demonstrate that dyslexic adults are deficient in processing
sounds and acoustic changes presented in rapid succession within tens to hundreds
of milliseconds. In line with the proposed pansensory processing deficit, responses
to rapidly presented tactile stimuli were diminished in the right somatosensory cortex
of dyslexic subjects, and abrupt visual stimuli captured attention in both visual hemifields
less effectively in dyslexic than normal-reading adults. Furthermore, dyslexics
showed right visual field advantage, suggestive of a left-sided “minineglect”. On the
basis of these and earlier findings we have proposed that limitations in both modality-specific
and more global attentional capacities could prolong input chunks for all
senses, thereby leading to anomalous cortical representations in dyslexic subjects
[1]. MEG provides a powerful tool for characterizing sensory processing deficits, but
further studies are needed to clarify the relationship between sensory-specific cortical
processing and phonological processing deficits in dyslexia.
[1] Hari, R., Renvall, H. 2001. Impaired processing of rapid stimulus sequences in
dyslexia. TICS 5, 525-532.
Korrespondenzautor:
Hanna Renvall
hanna@neuro.hut.fi
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