Heim-Grande-2010

Authors: Stefan Heim, Marion Grande, Elisabeth Meffert, Simon B. Eickhoff, Helen Schreiber, Juraj Kukolja, Nadim Jon Shah, Walter Huber, Katrin Amunts.

Article: Cognitive levels of performance account for hemispheric lateralisation effects in dyslexic and normally reading children,.

Publication: Neuroimage (Elsevier). Volume 53, Issue 4, Pages 1346-1358 2010 | DOI: 10.1016/j.neuroimage.2010.07.009

[Full Text]

Abstract

Recent theories of developmental dyslexia explain reading deficits in terms of deficient phonological awareness, attention, visual and auditory processing, or automaticity. Since dyslexia has a neurobiological basis, the question arises how the reader’s proficiency in these cognitive variables affects the brain regions involved in visual word recognition. This question was addressed in two fMRI experiments with 19 normally reading children (Experiment 1) and 19 children with dyslexia (Experiment 2). First, reading-specific brain activation was assessed by contrasting the BOLD signal for reading aloud words vs. overtly naming pictures of real objects. Next, ANCOVAs with brain activation during reading the individuals’ scores for all five cognitive variables assessed outside the scanner as covariates were performed. Whereas the normal readers’ brain activation during reading showed co-variation effects predominantly in the right hemisphere, the reverse pattern was observed for the dyslexics. In particular, middle frontal gyrus, inferior parietal cortex, and precuneus showed contralateral effects for controls as compared to dyslexics. In line with earlier findings in the literature, these data hint at a global change in hemispheric asymmetry during cognitive processing in dyslexic readers, which, in turn, might affect reading proficiency.

Tagged as: altbrain, attention shifting, fMRI, left hemisphere, right hemisphere, visual attention, and visual word recognition

Citation:

Stefan Heim, Marion Grande, Elisabeth Meffert, Simon B. Eickhoff, Helen Schreiber, Juraj Kukolja, Nadim Jon Shah, Walter Huber, Katrin Amunts,
Cognitive levels of performance account for hemispheric lateralisation effects in dyslexic and normally reading children,
NeuroImage, Volume 53, Issue 4, 2010, Pages 1346-1358,
https://doi.org/10.1016/j.neuroimage.2010.07.009

Excerpts from Full Text / Notes:
Consequently, the double dissociation between variable (phonological/attention) and group observed in the present study reects the interaction of the reading system with these variables. For the normal readers, left middle frontal cortex is involved in grapheme-to-phoneme conversion anyway; the role of its right homologue depends on the child’s phonological abilities, but not on attention (the same also holds forright inferior parietal cortex, which is also involved in grapheme-to-phoneme conversion). Conversely, in dyslexic readers, and independently of the individual level of phonological awareness, the middle frontal gyrus activation during grapheme processing depends on the child’s ability to shift attention in order to support the reading process. In sum, this analysis tentatively describes a mechanism how two independent variables representing potential causes of dyslexia differentially affect the reading network in the brain, but do so in regions reciprocally related to these functions.
Future research will need to look more closely at the relationship of different aspects of attention on different aspects of phonological processing, and the function of this relationship for dyslexia. The present study sheds some light on brain cognition relationships in dyslexic and normal readers, showing that phonological awareness and reorienting of attention modulate brain activation during orthographic processing in brain regions associated with the other of the two functions.

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