Auditory P2 is Reduced in 5 Month old Infants From Dyslexic Families

Abstract

In this ERP study we examined the auditory processing of 5-month-old infants from dyslexic families (n=121) and controls (n=73) as part of a national longitudinal research program in The Netherlands on developmental dyslexia. A natural manipulated speech stimulus /bak/ was presented to these infants as the standard stimulus (about 400 repetitive presentations) in an oddball paradigm. Infants were either awake, watching a silent video, or asleep during the repetitive presentation of the stimulus. In this study we tested the prediction from a dynamic neuronal model study that the P2 should be reduced in infants from dyslexic families. The data indicates that infants from dyslexic families have a reduced P2 in the frontal-central-parietal regions in both hemispheres. During sleep the P2 amplitude was reduced compared with the awake state, but there was no difference between sleeping stages. Somewhat unexpectedly we did not find gender differences in this study. Cortical generators of the P2 were found in the auditory cortex and in Wernicke’s and Broca’s area. P2 amplitude explains 18% of the variance in verb production of the same infants at the age of 17 months. A discriminant analysis shows that infants are classified as deficient in auditory processing in 10% of the controls and 35% of the infants from dyslexic families. These numbers are well in line with the normal population risk and the elevated risk in infants from dyslexic