Bergmann-Hutzler-2005

Authors: Jürgen Bergmann, Florian Hutzler, Wolfgang Klimesch, Heinz Wimmer.

Article: How is dysfluent reading reflected in the ERP?.

Publication: Journal of Neurolinguistics (Elsevier). Volume 18, Issue 2, Pages 153-165 2005 | DOI: 10.1016/j.jneuroling.2004.11.004

[Full Text]

Abstract

The present study focused on early ERP differences between dyslexic and fluent readers which may reflect a deficit in letter string processing. We compared the ERPs of dyslexic and fluent readers (20 German-speaking boys in each group, age 13–14 years) in response to words and consonant strings. Due to the regularity of German orthography, our dyslexic readers suffered mainly from impaired fluency and not from errors. In a word task each trial presented short, highly frequent words and the occurrence of a pseudoword among the eight items of a trial had to be reported. In a corresponding string task each trial presented consonant strings and the occurrence of a word among the strings had to be reported. The blocked presentation allowed expectations about the nature of the stimuli and their timing. Dyslexic readers exhibited a reduced CNV in anticipation of words and strings, which in the case of words was followed by a compensatory enhanced N220. This pattern was limited to left posterior sites and may reflect a sluggish response of brain regions involved in visual letter string processing.

Tagged as: disorientation, event related potentials (ERP), reading fluency, and visual processing

Citation:

Jürgen Bergmann, Florian Hutzler, Wolfgang Klimesch, Heinz Wimmer,
How is dysfluent reading reflected in the ERP?,
Journal of Neurolinguistics, Volume 18, Issue 2, 2005, Pages 153-165

Excerpts from Full Text / Notes:
Discussion
A first finding was the failure to detect substantial ERP latency deficits of dyslexic readers. Such a deficit would be expected from the general slow reading performance of our dyslexic participants….  The
reasons for this divergence are not obvious. … A further, more general explanation for the absent dyslexic ERP latency deficit in the present and some other ERP studies is offered by the position of Klimesch et al. (2004) that ERPs reflect a synchronization of brain oscillations, like alpha and theta. For example, the present P130 component in response to letter strings may arise from the reset and synchronisation of the continuous alpha and theta rhythms to the onset of the stimulus. If this is the case, and, furthermore, if the extent and type of resetting and synchronisation is not differentially affected by the present task, then no latency delay is expected when dyslexic readers exhibit alpha and theta frequencies in the normal range.

NOTE: This could be a possible explanation of orientation vs. disorientation.  That is, the “normal” alpha and theta frequencies could reflect that the dyslexic teenagers in this small group study were able to maintain orientation during the measured tasks.