Dyslexia: the possible benefit of multimodal integration of fMRI- and EEG-data

Abstract

Biological research about dyslexia has been conducted using various neuroimaging methods like functional Magnetic Resonance Imaging (fMRI) or Electroencephalography (EEG). Since language functions are characterized by both distributed network activities and speed of processing within milliseconds, high temporal as well as high spatial resolution of activation profiles are of interest: "where" can dyslexia specific activations be detected and "when" do language processes start to diverge between dyslexics and controls? Due to the network character of language processing, fMRI-constrained distributed source models based on EEG-data were computed for multimodal data integration. First single-case results show that this method could be a promising approach for the understanding of a repeatedly described experimental finding for dyslexia like that of an overactivation in inferior frontal language areas. Multimodal data analysis for the subjects presented here could probably demonstrate that inferior frontal overactivations are the consequence of a phonological deficit and could represent ongoing articulation processes used to solve phonologically challenging tasks.

The development of print tuning in children with dyslexia: Evidence from longitudinal ERP data supported by fMRI

“…Underactivation in the middle portion of the middle temporal gyrus occurred in a study employing a pseudoword rhyming task (Grunling et al, 2004). Thus, also the anterior MTG underactivation may reflect a deficit in phonological processing.…”

Meta-analyzing brain dysfunctions in dyslexic children and adults

“…Only 2 adult studies relied on a more liberal threshold which may have inflated the number of input foci (Brambati et al, 2006;Rumsey et al, 1997). However, the comparatively large number of overactivation foci from adult studies does not result from these two studies with the more liberal thresholds, but from the two studies from our lab with German dyslexic participants Wimmer et al, 2010; see also Grünling et al, 2004).…”

“…In addition, we included a recent large study (presented as a poster) from a multi-center project in which our lab was involved (Maurer et al, 2010). To clearly differentiate between children and adults, 4 studies with adolescents were excluded (Georgiewa et al, 1999;Grünling et al, 2004;Hoeft et al, 2007;Kronbichler et al, 2006). Two further studies Schulz et al, 2008) were excluded in favor of more recent ones with the same participants (Meyler et al, 2008;Schulz et al, 2009).…”

Visual spatial attention and speech segmentation are both impaired in preschoolers at familial risk for developmental dyslexia

“…Notably, developmental changes in right TPJ activation have been linked to reading acquisition in normally developing children (Turkeltaub, Gareau, Flowers, Zeffiro & Eden, 2003) and some studies have observed a right TPJ deficiency in dyslexics (e.g. Hoeft et al, 2006;Grü nling et al, 2004).…”