Impaired non-speech auditory processing at a pre-reading age is a risk-factor for dyslexia but not a predictor: an ERP study.

Impaired auditory sensitivity to amplitude rise time (ART) has been suggested to be a primary deficit in developmental dyslexia. The present study investigates whether impaired ART-sensitivity at a pre-reading age precedes and predicts later emerging reading problems in a sample of Dutch children. An oddball paradigm, with a deviant that differed from the standard stimulus in ART, was administered to 41-month-old children (30 genetically at-risk for developmental dyslexia and 14 controls) with concurrent EEG measurement.

Differences in AERP responses and atypical hemispheric specialization in 17-month-old children at risk of dyslexia.

To determine the auditory event-related potential (AERP) correlates of phoneme perception in 17-month-old children at risk of dyslexia and controls, AERPs were elicited by standard (/bAk/) and deviant (/dAk/) word stimuli presented in an oddball paradigm. The at-risk children tended to show delayed P1 and P2 peaks for standard stimuli. Hemispheric group differences were observed for N2 amplitude and P1 latency, suggesting atypical processing of spoken words in at-risk children.

Cortical categorization failure in 2-month-old infants at risk for dyslexia.

Cortical auditory categorization was assessed in 2-month-old infants at genetic risk for dyslexia and controls. Manipulated /bAk/ and /dAk/ speech stimuli were used as frequently presented standards. The neuroelectric brain responses of the control infants were highly sensitive to the phoneme boundary that separated these stimuli, but the infants at risk showed no signs of cortical categorical perception.

Efficiency of visual information processing in children at-risk for dyslexia: habituation of single-trial ERPs.

To investigate underlying learning mechanisms in relation to the development of dyslexia, event-related potentials to visual standards were recorded in five-year-old pre-reading children at-risk for familial dyslexia (n=24) and their controls (n=14). At the end of second grade the children aged 8 years were regrouped into three groups according to literacy level and risk factor. Single-trial analyses revealed N1 habituation in the normal-reading controls, but not in the normal-reading at-risks, and a N1 amplitude increase in the group of poor-reading at-risks and poor-reading controls.

Mismatch response is absent in 2-month-old infants at risk for dyslexia.

This study examined auditory processing in 2-month-old infants at genetic risk for dyslexia and in controls. Manipulated natural speech stimuli (/bAk/ and /dAk/), at either side of the phoneme boundary, were presented to these infants and their automatic cortical deviance responses were recorded. Control infants showed two distinct mismatch responses, thus extending similar findings reported with kindergartners in terms of topographical distribution and cortical sources.

Differences at 17 months: productive language patterns in infants at familial risk for dyslexia and typically developing infants.

Productive vocabulary composition is investigated in 17-month-old children who are participating in an ongoing longitudinal dyslexia research project in the Netherlands. The project is searching for early precursors for dyslexia and follows a group of children who are genetically at risk for dyslexia and a control group during the first 10 years of their lives. Among other measures, the Dutch version of the MacArthur Communicative Development Inventory: Words and Sentences (N-CDI) is used to investigate early vocabulary development.