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.

ERN, ERP, Eriksen flanker task, acute tryptophan depletion, adult, anger, article, attenuation, brain depth stimulation, clinical article, clinical trial, controlled clinical trial, controlled study, crossover procedure, depression, double blind procedure, electrocardiogram, electroencephalogram, eriksen flanker task, error detection, evoked cortical response, fatigue, heart rate, human, human experiment, male, mental task, mood change, negative feedback, normal human, priority journal, psychologic assessment, randomized controlled trial, reaction time, serotonin, tension, tryptophan, tryptophan brain level,
Journal of Psychopharmacology
Erasmus MC: University Medical Center Rotterdam

Veen, F, Evers, E.A.T, Mies, G.W, Vuurman, E.F.P.M, & Jolles, J. (2010). Acute tryptophan depletion selectively attenuates cardiac slowing in an Eriksen flanker task. Journal of Psychopharmacology, 24(10), 1455–1463. doi:10.1177/0269881109103801