Specific neurophysiological markers of developmental dyslexia in automatization and auditory perception

Developmental dyslexia is a learning disorder that impairs a child*s ability to
read and write. Estimates of the prevalence of dyslexia range from 3% to 10% of
the population. Among children at familial risk for dyslexia (defined as
children with at least one dyslexic parent), the prevalence is up to 60%,
demonstrating a clear genetic basis of the disorder. Moreover, there is high
degree of comorbidity between dyslexia and other developmental disorders.
Dyslexia has lifelong persistence, posing a severe risk to academic
attainments, occupational perspectives and psycho-somatic well-being. In order
to minimize the detrimental effects of dyslexia, it is vitally important to
detect cases of dyslexia at the youngest possible age. Since dyslexia is
partially hereditary and often overlaps with other developmental disorders,
detecting specific cases of dyslexia involves not only setting apart dyslexic
and typically developing children, but also at-risk children who develop
dyslexia and who do not, as well as dyslexic children and children with other
developmental disorders. Despite decades of intensive research, there is
relatively little research that has investigated specific markers of dyslexia.
The proposed study is intended to fill this gap. In the current study, two
Event-Related Potential (ERP) experiments will be conducted to reveal specific
neurophysiological markers of dyslexia. In both experiments, we use
ElectroEncephaloGraphy (EEG) to record brain activities of the children. On the
basis of previous research, we predict specific differences in the pattern of
brain activities between groups, which allow us to detect specific cases of
dyslexia.

The objective of the current study is to reveal specific neurophysiological
markers of dyslexia, thus contributing to the early diagnosis and intervention
of dyslexia. To fulfill this objective, two ERP experiments will be conducted
in the domain of automatization and auditory perception, respectively. In both
experiments, the primary objective is to reveal robust group differences in the
pattern of brain activities between dyslexic and control children. Secondly, in
order to test the specificity of the ERP measures as determinants for dyslexia,
we aim at investigating the differences between dyslexic children and at-risk
children who do not develop dyslexia. In addition, since dyslexia has a high
degree of comorbidity with specific language impairment (SLI), identifying
specific cases of dyslexia involves setting apart dyslexia and SLI. Thus an
additional study will be conducted in collaboration with Potsdam University to
investigate the differences between dyslexic children and SLI children in the
domain of auditory perception.

The current study is a quasi-experimental observational study consisting of two
ERP experiments. In both experiments, group assignment is based on performance
of the children in the Diagnosis of Dyslexia study, a behavioral study
targeting the diagnosis of dyslexia.

The children and their parents will be invited to the Ambulatorium of the
University of Groningen. During the experiments, the ElectroEncephaloGraphy
(EEG) will be recorded while the children are listening to sounds presented via
a headphone or viewing pictures displayed on a screen. Including preparation of
the EEG facility, the recording lasts 90-120 minutes. The EEG technique is
frequently used in studies with newborns and young children, and poses no risks
to the health of the participants. Besides, the children will be tested under
passive paradigms, i.e., they do not have to make any response. Thus the study
costs only time. The main benefit for the children is that possible reading
problems can be detected at an early stage of reading acquisition, which is
vitally important if we are to minimize the negative effects of dyslexia. In
addition, the children will receive a small present for their participation.