1. ¹Psychiatric University Hospital Zürich, Clinic for Social and General Psychiatry, Zürich, Switzerland
2. ²Department of Psychiatry, University of Ulm, Ulm, Germany

Correspondence: Dr AB Brühl, Psychiatric University Hospital Zürich, Clinic for Social and General Psychiatry, Lenggstrasse 31, Zürich CH-8032, Switzerland, Tel: + 41 44 384 2685, Fax: + 41 44 383 4456, E-mail: annette.bruehl@puk.zh.ch

Received 15 June 2009; Revised 8 September 2009; Accepted 8 September 2009; Published online 21 October 2009.

Abstract

Serotonergic and noradrenergic pathways are the main targets of antidepressants. Their differential effects on emotion processing-related brain activation are, however, to be further characterized. We aimed at elucidating the neural sites of action of an acute differential serotonergic and noradrenergic influence on an emotion-processing task, which was earlier shown to be associated with depressiveness. In a single-blind pseudo-randomized crossover study, 21 healthy subjects (16 subjects finally included in the analysis) participated to ingest a single dose at three time points of either 40 mg citalopram, a selective serotonin-reuptake inhibitor, 8 mg reboxetine, a selective noradrenaline-reuptake inhibitor, or placebo 2–3 h before functional magnetic resonance imaging (fMRI). During fMRI, subjects performed a task comprising the anticipation and perception of pictures of either 'known' (positive, negative, neutral) or 'unknown' valence (randomly 50% positive or negative). In direct comparison with citalopram and with placebo, reboxetine increased brain activity in the medial thalamus. Citalopram modulated certain prefrontal and insular areas more prominently. Other frontal and parieto-occipital areas were modulated by both drugs. In conclusion, the functional network involved in emotional information processing could be modulated by the acute application of selective noradrenergic and serotonergic drugs revealing a noradrenergic effect in thalamic and frontal areas, and a prefrontal and insular focus of serotonergic modulation. These findings could have implications for future selection criteria concerning personalized antidepressant medication in depression.