Response selection and control are supposed to reflect important basal ganglia functions. Recently, we showed that the dopaminergic system may be especially important for response selection in compatible, but not in incompatible stimulus-response (S-R) relations. Research indicates that the dopaminergic system is influenced by the serotonergic system, but little is known about the involvement of the serotonergic system in response selection. Analyzing event-related potentials (ERPs) we show the 5-HT1A C(-1019)G polymorphism modulating response-related processes, but only in compatible S-R relations. This modulation was a function of the number of -1019 G alleles. Decreasing numbers of -1019 G alleles were stepwise related to increases in response selection efforts. The functional effect of the 5-HT1A C(-1019)G polymorphism has previously been shown to be specific for serotonergic 1 A autoreceptors of serotonergic neurons in the dorsal raphe nucleus (DRN). Due to this close relation of genotype effects to neuroanatomically dissociable structures, the results suggest that DRN serotonin 1 A autoreceptors are important for response selection. The results extend previous findings on the dopaminergic system to the serotonergic system. The examined functions are precisely regulated on a neuronal level, since neurophysiological and behavioural effects are driven in an allele-dose fashion. Because of this, the results are of importance for future clinical applications.

Beste, C., Domschke, K., Falkenstein, M., & Konrad, C., Differential modulations of response control processes by 5-HT1A gene variation, NeuroImage, 2010, 50: 764-771.