PB8. Methylphenidate modulates gain modulation processes during competitive auditory attention in a dose–response fashion

Abstract

The ability to selectively perceive and flexibly attend to relevant sensory signals in the environment is essential for adaptive behavior in everyday life. The fronto-striatal gain control mechanisms likely serve as an important regulatory interface of selective attention and perception. These gain control mechanisms are likely to be modulated by the dopaminergic system. In the current study, we administered methylphenidate (MPH) in two different dosages (0.25 mg/kg and 0.5 mg/kg) to healthy young adults in a single-blinded placebo-controlled study to examine the role of dopamine in regulating the gain control mechanisms. This was combined with high-density EEG recordings and source localization analyses in a dichotic listening task in which perceptual saliency was manipulated besides attentional focus resulting in conditions of low and high perceptual-attentional conflict. Compared to a placebo condition, we show that only at low MPH dosages (0.25 mg) performance was differentially modulated. No effects were observed using 0.50 mg MPH. The administration of 0.25 mg MPH reduced the effects of high perceptual-attentional conflict between discordant dichotic syllables. Interestingly, this was only the case for the right ear, which usually shows an advantage in verbal processing. This was reflected by specific EEG-correlates reflecting bottom-up attentional gating and top-down conflict monitoring processes. The results suggest that MPH modulates gain control processes during competitive auditory attention in a dose-dependent fashion. Yet, this modulatory effect depends on functional cerebral asymmetries.