Dynamic time warping in the study of ERPs in dyslexic children

Aim of this paper is to compute a normal ERP pattern (template) and to quantify the morphological characteristics of ERPs. ERPs were recorded from normal and dyslexic children in a passive and in an active condition. Dynamic time warping (DTW) was used to align the averaged ERPs of normal subjects. After the computation of the templates, individual averaged ERPs were aligned with the corresponding template, in order to automates the identification of the relevant ERPs components. The latencies of these components in normal and dyslexic subjects were compared in the two different conditions. ERPs components of dyslexic children were always delayed in respect to normal children. Statistically significant latency differences were noticed both in the short-latency waves, related to attention mechanisms, and in the long-latency waves, presumably related to memory processes. P1 latency in T4 differed in the two groups of children in both tasks, with p<0.05. Morphological differences between the ERPs of normal and dyslexic children were also noticed in the right hemisphere: N2 latency in T4 differed in the two groups of children with p<0.05. This result suggests that dyslexia is associated with more general disruptions of the cerebral functions than that confined to the classical linguistic areas.