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Maureen's research seeks to understand the neurotransmitter signaling pathways underlying emotional and cognitive processes, including mood, attention, reward, learning, memory, and stress response, and the neuropsychiatric disorders that can arise with disruption of these systems. Research focuses on neurotransmitter transporters that regulate the catecholamines, norepinephrine (NE) and dopamine (DA). The duration and intensity of NE and DA signaling in the brain (and additionally in the sympathetic autonomic nervous system in the case of NE) are limited by the presynaptically localized transporters for NE (NET) and DA (DAT) that clear released neurotransmitter through active transport into terminals. DAT and NET are both targets for psychostimulants, including those that treat attention-deficit hyperactivity disorder (ADHD). NET is also a target for tricyclic antidepressants, and NET-selective reuptake inhibitors (NSRIs), the latter also effectively treat ADHD. One focus of this research is to investigate genetic variation in the human NET and DAT genes and the consequences for transporter function, and contribution to psychiatric and cardiovascular disease. Transgenic mouse models allow for in vivo assessment of the effects of NET and DAT variants on catecholamine neuronal activity, physiology and behavior. Mouse projects include the study of the first NET knockin mouse (NET A457P), bearing a NET mutation identified in humans with postural orthostatic tachycardia. NET A457P mice recapitulate the NET deficiency observed in human carriers, and express cardiovascular and psychiatric-related phenotypes.