The Role of Serotonin on Affective Information Processing in Healthy Individuals

Abstract

Serotonin has a major role in affective information processing and innervates key neural structures in the circuitry underlying emotional regulation. As these processes are involved in clinical depression, reduced availability of serotonin has been associated with its pathophysiology. The aim of this review was to investigate the role of serotonin in modulating affective processing focussing particularly on research done in healthy volunteers. The amount of studies in healthy volunteers on this topic has been expanding rapidly over the last few years and already provided many insights into this process. It has been suggested that antidepressants do not directly influence mood, but that they work indirectly by effecting emotional processing. The present review describes the influence of serotonin in processing emotional stimuli en in reinforcement and decision making processing by methods of serotonin manipulation: i.e. administration of selective serotonin reuptake inhibitors (SSRI), tryptophan loading and acute tryptophan depletion. Results are in agreement with what Harmer and colleagues put forward, i.e. mood was not directly influenced by serotonin modulation, but affective information processing was. However, more research is needed, because many factors may influence these results, e.g. test paradigm, stimuli, duration of the serotonin manipulation, gender differences, consciousness, gene expression. This review provides insights that can be used to guide future research in assessing the therapeutic effect of medical interventions in clinical depression.