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Abstract #3708

Activation of Inferior Frontal Gyrus During Response Inhibition: Effects of Citalopram and Acute Tryptophan Depletion Depend on Neocortical 5-HT2A Receptor Levels

Julian Macoveanu1,2, Bettina Hornboll1,3, Rebecca Elliott4, Hartwig Siebner1,3, David Erritzoe3,5, Olaf B. Paulson1,3, Gitte M. Knudsen3,5, James B. Rowe3,6

1Danish research center for MR, Copenhagen University Hospital, Hvidovre, Denmark; 2Center for Integrated Molecular Brain Imaging, Copenhagen University Hospital , Copenhagen, Denmark; 3Center for Integrated Molecular Brain Imaging, Copenhagen University Hospital, Copenhagen, Denmark; 4Neuroscience and Psychiatry Unit, University of Manchester, Manchester, UK; 5Neurobiology Research Unit, Copenhagen University Hospital, Copenhagen, Denmark; 6Department of Clinical Neurosciences, Cambridge University, Cambridge, UK

Inhibiting actions is associated with the inferior frontal gyrus (IFG) and is regulated by serotonin. Here we explore the link between the serotonin receptor type 5-HT2A and activity in IFG during response inhibition. 17 subjects performed a Go/No-Go task during fMRI, with treatments to acutely increase (citalopram) or decrease (acute tryptophan depletion, ATD) serotonin, or no treatment. We also used 18-F-altanserin positron emission tomography to map 5-HT2A receptor binding. Individuals with low 5-HT2A had greater activation of IFG after ATD. Individuals with high 5-HT2A had greater activation after citalopram. Conclusion: effects of serotonergic treatments depend on individual differences in 5-HT2A.