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 Macoveanu^1,2, Bettina Hornboll^1,3, Rebecca Elliott⁴, Hartwig Siebner^1,3, David Erritzoe^3,5, Olaf B. Paulson^1,3, Gitte M. Knudsen^3,5, James B. Rowe^3,6

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.