http://repub.eur.nl/res/aut/27525/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/22157/ 2010-10-01T00:00:00Z In the present study, the effects of transiently lowering central serotonin levels by means of acute tryptophan depletion on measures of cognitive flexibility were examined. Flexible behaviour was measured in an Eriksen flanker task, and cardiac and electro-cortical responses to errors and congruent and incongruent stimuli were measured. The depletion was successful in lowering tryptophan levels and, as expected, it did not affect subjective mood. Depletion did not affect performance and electro-cortical measures and selectively affected cardiac measures. Depletion attenuated cardiac slowing to incongruent flanker stimuli but did not affect cardiac responses to congruent stimuli and errors. The selective effect on cardiac responses as compared to performance and electro-cortical measures was in accordance with earlier findings, as well as the attenuation of cardiac slowing. The selective effect on the cardiac response to incongruent stimuli was unexpected. Detailed analyses showed a close connection to the earlier reported attenuation of the cardiac response to negative feedback, and the effect is explained in terms of reduced anticipation of the feedback stimulus due to enhanced punishment prediction. © The Author(s), 2010. http://repub.eur.nl/res/pub/22884/ 2009-07-01T00:00:00Z Abstract Previous research has shown that low central serotonin, induced by acute tryptophan depletion (ATD), results in depressed mood and impairs cognition in healthy volunteers with a predisposition for depression. It remains unknown whether ATD affects emotional processing via mood changes or directly. In the present study we investigated the interaction between vulnerability for depression and the effect of ATD on mood, cognition and the associated brain activation. In a previous functional MRI study, we tested the effect of ATD during a combined cognitive and emotional Stroop task in healthy women without a family history of depression (FH-). In this study, we present the data of an additional group of 12 healthy women with a positive family history of unipolar depression (FH+). The effect of ATD on mood and Stroop performance was different for the FH+ group as compared with the FH- group. Scores on the depression sub-scale of the Profile of Mood States (POMS) did not correlate with performance changes, but did correlate with the anterior cingulate cortex response during Stroop interference. This study showed that a family history of unipolar depression interacts with the effect of ATD http://repub.eur.nl/res/pub/22883/ 2009-05-01T00:00:00Z http://repub.eur.nl/res/pub/29184/ 2008-08-01T00:00:00Z Rationale: Recent studies have shown that serotonin might be involved in performance monitoring, although the results have been inconclusive. Inconsistent results might be related to the type of pharmacological manipulation and the used behavioral and physiological measures. Objectives: The present study aimed at further specifying the role of serotonin in performance monitoring. Materials and methods: The effect of serotonin on performance monitoring was studied by using acute tryptophan depletion (ATD), a well-known method to transiently lower central serotonin levels. Twenty healthy male volunteers performed a time-estimation task and their event-related brain potential (ERP), behavioral, and cardiac responses to feedback stimuli were measured. Furthermore, subjective mood and amino-acid levels were determined. Results: As expected, ATD did not affect mood and lowered tryptophan levels. ATD attenuated cardiac slowing to negative feedback but did not affect responses to positive feedback, ERPs, and performance measures. Conclusions: The data point in the direction of a dissociation between cardiac and electro-cortical responses. Cardiac responses appear to be more sensitive to changes in serotonin metabolism and appear to reflect different aspects of the feedback stimulus. The phasic cardiac response appears to be an important measure that provides additional information about the impact of feedback stimuli and serotonergic functioning. http://repub.eur.nl/res/pub/36338/ 2007-01-01T00:00:00Z The present study examined the effects of acute tryptophan (Trp) depletion (ATD), a well-recognized method to lower central serotonin (5-HT) metabolism, on brain activation during a facial emotion perception task. Brain activation was measured using fMRI, and healthy female volunteers with a positive family history of unipolar depression (FH+) were compared to healthy female volunteers without such a history (FH-). Participants viewed two morphed faces and were instructed to choose between the faces based either on the intensity of the emotional expression (direct task) or the gender of the face (incidental task). In the FH+ group, depletion led to the expected lowering of mood, which partly determined the effect of depletion on performance and brain activation. A stronger mood lowering effect was associated with less accurate performance on faces expressing a negative emotion in the incidental task and a stronger right amygdala response to fearful faces in comparison to happy faces. These results were explained in terms of a mood-induced bias leading to a stronger impact of the expressed negative emotion which subsequently leads to more interference in the incidental task and a stronger amygdala response. It was concluded that the effects of ATD on mood, performance, and brain activation in a facial emotion perception task depend on family history of depression. Performance and brain activation partly depend on the effect of ATD on mood.