Faculty of Mathematics, Informatics and Natural Sciences, Department of Biology, Institute of Zoology, Neuroendocrinology and Human Biology Unit, Universität Hamburg, Hamburg, Germany.
Front Endocrinol (Lausanne). 2020 Apr 24;11:231. doi: 10.3389/fendo.2020.00231. eCollection 2020.
Hormonal transitions across the menstrual cycle may modulate human reward processing and reinforcement learning, but previous results were contradictory. Studies assessed relatively small samples ( < 30) and exclusively used within-subject designs to compare women in hormonally distinct menstrual cycle phases. This increased the risk of sporadic findings and results may have been disproportionally affected by expectancy effects. Also, replication studies are widely missing, which currently precludes any reliable inferences. The present study was intended as a conceptual replication of a previous study [(1), Neuropsychologia 84; = 15]. There, we had observed a reduction in avoidance learning capacity when women were in the high estradiol state of the late follicular phase as compared to the mid luteal phase with enhanced progesterone influence. These results conformed to the idea that estradiol and progesterone may antagonistically modulate dopaminergic transmission as a dopamine agonist and antagonist, respectively. Heightened progesterone in the luteal phase thereby supported the ability to learn from the negative outcomes of one's actions, while the follicular rise in estradiol interfered with this capacity. Here, we re-examined the above described within-subject difference between the follicular and the luteal phase in a between-subjects design. Seventy-five women were tested once with a probabilistic feedback learning task, while being either in the follicular (36 women) or luteal phase (39 women), and were compared for phase-related differences in behavior. Secondly, we combined the new data with data from three previous studies from our laboratory that used the same task and menstrual cycle phases. This meta-analysis included only data from the first test day, free of any biasing expectancy effects. Both analyses demonstrated the consistency of the decline in avoidance learning in the follicular relative to the luteal phase. We also showed that this decline reliably occurred in all of the included samples. Altogether, these results provide evidence for the consistency of a behavioral difference and its apparent association with a transient change in hormonal state that occurs in the natural menstrual cycle. Our findings may also open new avenues for the development of reliable between-subjects test protocols in menstrual cycle research.
月经周期中的激素变化可能会调节人类的奖励处理和强化学习，但之前的结果存在矛盾。这些研究评估的样本相对较小（<30），并且仅使用了内源性设计来比较处于不同激素状态的女性在月经周期的不同阶段。这增加了偶然发现的风险，并且结果可能会受到期望效应的不成比例影响。此外，目前还广泛缺乏复制研究，这使得任何可靠的推断都无法进行。本研究旨在对之前的一项研究进行概念复制 [(1)，Neuropsychologia 84; = 15]。在该研究中，我们观察到当女性处于卵泡晚期的高雌激素状态时，与黄体中期相比，回避学习能力下降，而孕激素的影响增强。这些结果符合这样的观点，即雌激素和孕激素可能分别作为多巴胺激动剂和拮抗剂拮抗地调节多巴胺传递。黄体期孕激素水平升高有助于从自身行为的负面结果中学习，而卵泡期雌激素水平升高则干扰了这种能力。在这里，我们在被试间设计中重新检查了卵泡期和黄体期之间的上述内源性差异。75 名女性接受了一次概率反馈学习任务的测试，其中 36 名女性处于卵泡期，39 名女性处于黄体期，并比较了两种激素状态下的行为差异。其次，我们将新数据与来自我们实验室的三项先前研究的数据结合起来，这些研究使用了相同的任务和月经周期阶段。这项荟萃分析仅包括来自第一天测试的数据，没有任何偏向性的期望效应。这两项分析都证明了在卵泡期相对于黄体期，回避学习能力下降的一致性。我们还表明，这种下降在所有包含的样本中都可靠地发生。总的来说，这些结果为在自然月经周期中发生的行为差异及其与激素状态的短暂变化之间的明显关联的一致性提供了证据。我们的发现也可能为在月经周期研究中开发可靠的被试间测试方案开辟新的途径。
