Ovarian steroids and their influence on hippocampal memory function and morphology

摘要: The ovarian steroids estradiol and progesterone play a critical role in the regulation of hippocampal plasticity. Estradiol has been shown to increase growth new spines synapses facilitate long-term potentiation. In line with findings on cellular level, animal studies evidence beneficial effects hippocampus-dependent memory. Although much less investigated, can counteract several estradiol-related effects. Unfortunately, human about hormonal hippocampus memory are rare highly equivocal. present thesis aims contribute data understanding hippocampus. For this purpose, four experiments were conducted assessing performance as well structure activity by means magnetic-resonance tomography. Experiment 1 investigated consequences pharmacologically-induced decreases synthesis. study, postmenopausal women suffering from hormone-sensitive breast cancer age-matched controls tested before onset anti-hormone therapy three six months later. Behaviorally, was associated worse specific subdomain verbal On neuronal increased neural responses anterior cingulate prefrontal cortex during source task. Results suggest that impaired activity. 2 made use polymorphism differences serum levels men. Hippocampal volume examined across genotype groups within independent cohorts, differing respect their genetic disposition either high or low levels. Analysis structural brain 1 Summary - 16 - images showed, group had higher volumes posterior both hemispheres. contrast, did not differ significantly between groups. These results show E2 is macroscopic Experiments 3 4 two phases menstrual cycle. experiments, once early follicular phase, when estrogen low, luteal which at medium peak its maximum. 3, functional neuroimaging recorded encoding emotional neutral pictures cycle phases. Retrieval days after outside scanner. Behavioral analyses yielded significant valence interaction for recollection-based memory, mainly driven negative high- relative low-hormone phase. areas showed variations hormones decrease efficacy negatively valenced arousal stimulate consolidation. existing literature, compared phase high. Findings highlight volume. summary, underscore variety system sensitivity experimental factors. Furthermore, current least part inconsistency literature be accounted differeniating -independent functions.