[Cognitive evoked potentials in autistic children]

The aim of this study was to examine the latency, amplitude and distribution of N400 potential in order to evaluate the semantic processing capacity in autistic children and in children suffering from Asperger s syndrome (AS), and to compare them with a control group.

24 autistic children, six boys with AS and 25 controls, aged between 6 and 14 years old. The cases were examined using the DSM IV diagnostic criteria. Auditory stimulation was performed with pairs of congruent and incongruent words: two lists of 20 pairs of semantically related words (congruent) and 20 pairs of words with no semantic relationship whatsoever (incongruent).

The most striking parameter is the increase in latency in N400 for the group of autistic children, which did not occur in the group of children with AS. Maximum N400 negativity for the children with autism was found in the left frontocentral region. No significant differences were observed for the amplitude of N400 between the three groups that were studied.

Neurophysiologically, the autistic children and those affected by AS perhaps use different neuronal networks in semantic processing. The N400 wave can be a valid test for monitoring verbal processing in these children.