Poster A22, Saturday, March 24, 1:30–3:30 pm, Exhibit Hall C
C957T Polymorphism in dopamine D2 receptor gene predicts sequence learning in younger adults
Beth Westphal1, Mark A. Gluck2, Jessica R. Petok1; 1St. Olaf College, Northfield, MN, 2Rutgers University, Newark, NJ
Previous patient work suggests that feedback-based sequence learning, or learning a sequence of events leading to reward, relies on mesolimbocortical dopaminergic mechanisms, whereby lower levels of dopamine corresponds to poorer learning. We tested this hypothesis using a healthy younger sample to see whether individual differences in dopamine genotype may influence feedback-based sequence learning. Specifically, the C957T single nucleotide polymorphism (SNP) of dopamine receptor D2 (DRD2) regulates DRD2 availability in the reward-mediating mesolimbocortical pathway, such that carriers of the C-allele have less DRD2 expression than T/T homozygotes. In the present study, healthy college-aged adults, grouped as C/C, C/T, or T/T, completed a feedback-based sequence learning task. As predicted, significantly fewer C-allele carriers were able to reach criterion and learn the full sequence compared to T/T homozygotes. Of those participants who met criterion, T/T homozygotes tended to show better performance in the feedback-based sequence learning phase (which depends on dopaminergic functioning) compared to participants with the C/C or C/T genotype. Of note, no effects of DRD2 were observed in a probe or retest phase, which are thought to be dopamine independent. The results of this study support previous work that implicates dopamine as an underlying mechanism of feedback-based sequence learning, and expands on these findings to show that dopamine genes help explain individual variability in sequence learning performance. Because our sample was racially diverse, future analyses will explore the relationship between race, genotype, and sequence learning performance.
Topic Area: EXECUTIVE PROCESSES: Development & aging