A comparative review of the psychophysiology of attention in children with and without attention deficit hyperactivity disorder

Abstract

The present review focuses on the development of attention as indexed in the electrical activity of the brain under a systematic framework of attention-related paradigms and experimental tasks in typically developing children (TDC). The framework is organized according to the filter and selective-set paradigms of attention research and experimental tasks that these models commonly use. The first part of the review discusses age-variant changes in the event-related potentials (ERPs) of TDC. Age affects the parameters of the various attention-related components (latencies and amplitudes) independently and differentially. The changes are mainly in the form of decreasing latencies, showing that aging increases the speed and efficiency of attentional processing. High task difficulty and cognitive load produce a shift in TDC from early selection, which involves a perceptual analysis, to late selection, which involves target detection. The second part of the review discusses attentional processing in children with attention deficit hyperactivity disorder (ADHD). Relative to TDC, ERP differences in ADHD are mainly represented in component amplitudes, which normally vary according to task difficulty and cognitive load. The literature permits a review of the differences between children with ADHD and age-matched TDC in not only ERPs but also in resting electroencephalogram (EEG) and event-related oscillations (EROs). Some of the differences between children with ADHD and TDC are quantitative and in the form of maturational lag, while others are qualitative and in the form of maturational deviance. The early gamma-band response (GBR) appears to be a significant biomarker of ADHD. The match-and-utilization model, which delineates the pervasive role that early GBR plays in the bottom-up and top-down processes of attention, applies to ADHD. The integrative approach of the present review reveals the gaps in the relevant literature and suggests directions for future studies by way of which a comprehensive understanding of ADHD may be possible.