Original Research ARTICLE
DAT1 genotype and menstrual cycle, but not hormonal contraception, modulate reinforcement learning: Preliminary evidence
- 1University of Hamburg, Germany
Hormone by genotype interactions have been widely ignored by cognitive neuroscience. Yet, the dependence of cognitive performance on both baseline dopamine (DA) and current 17ß-estradiol (E2) level argues for their combined effect also in the context of reinforcement learning. Here we assessed how the interaction between the natural rise of E2 in the late follicular phase (FP) and the 40 base-pair variable number tandem repeat polymorphism of the dopamine transporter (DAT1) affects reinforcement learning capacity. 30 women with a regular menstrual cycle performed a probabilistic feedback learning task twice during the early and late FP. In addition, 39 women, who took hormonal contraceptives (HC) to suppress natural ovulation, were tested during the ‘pill break’ and the intake phase of HC. The present data show that DAT1-genotype may interact with transient hormonal state, but only in women with a natural menstrual cycle. We found that carriers of the 9-repeat allele (9RP) experienced a significant decrease in the ability to avoid punishment from early to late FP. Neither homozygote subjects of the 10RP, nor subjects from the HC group showed a change in behavior between phases. These data are consistent with neurobiological studies that found that rising E2 may reverse DA transporter function and could enhance DA efflux, which would in turn reduce punishment sensitivity particularly in subjects with a higher transporter density to begin with. Taken together, the present results, although based on a small sample, add to the growing understanding of the complex interplay between different physiological modulators of dopaminergic transmission. They may not only point out the necessity to control for hormonal state in behavioral genetic research, but may offer new starting points for studies in clinical settings.
Keywords: estrogen, dopamine transporter, reinforcement learning, gender, steroid hormone, Hormonal contraception
Received: 13 Oct 2017;
Accepted: 09 Feb 2018.
Edited by:Takayoshi Ubuka, Monash University Malaysia, Malaysia
Reviewed by:Aaron Gruber, University of Lethbridge, Canada
Keith M. Kendrick, University of Electronic Science and Technology of China, China
Copyright: © 2018 Jakob, Ehrentreich, Holtfrerich, Reimers and Diekhof. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Prof. Esther K. Diekhof, University of Hamburg, Hamburg, Germany, firstname.lastname@example.org