Time-on-task analysis using wavelet networks in an event-related potentialstudy on attention-deficit hyperactivity disorder

Objective: The aim of this event-related potential (ERP) study was to test time-on-task analysis at the level of single sweeps in a clinical trial. Si nce inattentiveness is one of the main symptoms of attention-deficit hypera ctivity disorder (ADHD). this child psychiatric disorder was chosen as an e xemplary application. Methods: Twenty-four healthy and 24 ADHD boys, aged 9-15 years, performed a n auditory selective attention task fur about 5 min. ERP single trials were analyzed using wavelet networks. Time-on-task analysis was applied to omis sion errors, reaction time and slow ERP components (frontal negativity, par ietal positivity), represented by a low-frequency wavelet component. Results: Both performance and ERP measures showed distinct temporal al dyna mics. Time-on-task effects were not only linear, but also of higher order a nd started after less than 1 min. For ADHD children, earlier time-on-task e ffects, i.e. an earlier increase of omission errors and frontal negativity, resulted. Healthy children could allocate more attentional resources jurin g the course of the experiment. Conclusion: Time-on-task analysis at the level of single trials revealed ph enomena probably reflecting ADHD children's attentional deficits. Thus, a m ore differentiated ERP analysis may provide a better understanding of the p athophysiological background in neuropsychiatric disorders. (C) 2001 Elsevi er Science Ireland Ltd. All rights reserved.