Reduced P3 amplitude of the event-related brain potential: its relationship to language ability in autism.

Several studies have found that P3 amplitude of the auditory event-related potential is smaller in autistic than in normal children. The present study investigated whether this characteristic bears any relationship to the degree of language impairment and/or level of intellectual ability of autistic persons. Seventeen autistic children, ranging from 8-19 years of age, and 17 age- and gender-matched normal children participated. Event-related potentials to phonetic ("Da") and chord (piano) stimuli were recorded from three scalp locations: vertex (Cz), right hemisphere (RH), and left hemisphere (LH), during a discrimination task. A battery of language tests was given to autistic children. Compared to normal subjects, autistic subjects showed a significantly smaller P3 amplitude to phonetic stimuli for Cz and LH recording sites. However, no group difference in P3 amplitude to the phonetic stimulus was found for the RH. Furthermore, no group differences in P3 amplitude were found for the chord stimulus at any recording site. Impaired language ability was related to greater RH P3 amplitude, particularly to the chord stimulus. The possibility of differential hemispheric involvement in the attentional deficits of autistic children is raised.