The right hemisphere fails to respond to temporal novelty in autism: Evidence from an ERP study

Objective: This study aimed to investigate electrophysiological correlates of initial attention orienting to temporally novel sound in children with autism (CWA). Methods: Twenty-one CWA (4-8 years) and 21 age-matched typically developing children (TDC) were presented with pairs of clicks separated by a 0.5 s intra-pair interval, with longer (7-9 s) intervals between pairs. Children watched a silent movie during click presentation. We assessed EEG perturbations and event-related potentials (ERP) in response to Sounds of different temporal novelty - first (S1) and second (S2) clicks in the pair. Results: In TDC, the early attention-modulated midtemporal N1c wave evoked by S1 and corresponding EEG phase locking and power increase were right-lateralized and were bilaterally higher than those evoked by S2. CWA demonstrated abnormal S1 responses, characterized by reduced N1c amplitude and EEG phase locking in the right midtemporal region. reversed leftward lateralization of the phase locking, and diminished later frontal N2 wave. Their brain responses to S2 Were essentially normal. Conclusions: The impaired right hemispheric processing of temporary and contextually novel information and suboptimal lateralization of normally right-lateralized attention networks may be important features of autistic disorder. Significance: Results of this study contribute to the understanding of autism neurobiology. (C) 2009 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.