Neurochemical and neurophysiological bases of executive control

The aim of this work is to further understanding into the biological bases of human executive control through an integration of neuropsychology, psychopharmacology and functional imaging. Executive control includes the prototypical executive functions of response inhibition and error awareness. Response inhibition can be further divided into action cancellation and action restraint, which were assayed with the stop signal (SST) and Error Awareness (EAT) tasks, respectively. The EAT, which is a modified go-no go paradigm, was also used to measure error awareness behaviour. Monoamine neurotransmitters, specifically dopamine, noradrenaline and serotonin, were modulated during task performance with acute doses of methylphenidate (a dopamine and noradrenaline reuptake inhibitor), atomoxetine (a noradrenaline reuptake inhibitor), citalopram (a serotonin reuptake inhibitor) and cabergoline (a D2 agonist). The pharmacoimaging correlates of task performance were also examined with functional magnetic resonance imaging (fMRI). All experiments adhered to a randomised, double blind, placebo-controlled, crossover design and were limited to 18-35 year old healthy right-handed