Browsing by Author "von Bagh, Anna"

Objectives. Motivational contexts exert a profound influence on behavior biasing actions in sometimes detrimental ways. In Pavlovian bias, reward-predicting conditioned cues elicit approach behavior while aversively associated cues elicit withdrawal, with capacity to impact instrumental goal-driven behavior. Similar bias has been suggested to be produced by instrumental learning. Motivational biases have been linked to dopaminergic system but the precise role of dopamine in their modulation is unclear. The present study investigated genetically driven variation in Pavlovian and instrumental learning biases by comparing task performance in subjects carrying different variants of two dopaminergic SNPs, COMT Val108/158Met and DRD2/ANKK1Taq1A. Associations with BMI, diet, age and gender were studied. All subjects were expected to show motivational bias while no direct hypotheses were made concerning genotypic or lifestyle-mediated effects due to exploratory nature of the study. Methods. 160 subjects completed a probabilistic Go/NoGo learning task in an experimental within-subject design. Generalized mixed-model logistic regressions were used to predict differences by genotype in Go responding with and without covariants. Differences by genotype in computationally modelled latent bias estimates were studied with linear regression. Results and Conclusions. Confirming expectations, an overall effect of motivational bias and a general bias towards active responding were found. Relative to Val/Met and A1+, carriers of COMT Val/Val and Taq1A A1- variants showed superior learning of correct Go responses, indicating enhanced instrumental bias. BMI was inversely associated with learning rate while diet, age and gender did not explain variance. Results partly contradict previous findings and highlight the mixed nature of research regarding associations between dopaminergic SNPs and motivational biases.