Whole-Brain Dynamics in the Natural Menstrual Cycle vs. an Ovarian Stimulated Cycle: Impact of Hormonal Fluctuations on Healthy Women Undergoing Ovarian Stimulation

The investigators aim is to investigate the brain's dynamic complexity across three phases of an ovarian stimulation cycle (basal, pre-OPU, mid-luteal), to observe the impact of externally administered hormones, and compare it with the corresponding phases of a natural menstrual cycle (early follicular, pre-ovulatory, mid-luteal) in the same woman. Brain activity patterns will be examined using resting-state fMRI in a sample of young, healthy, naturally cycling women.

Inclusion Criteria: * Age group: 25 - 35 years old * BMI: 20 - 30 * Anti-Mullerian Hormone (AMH): 1.3 - 5.9 ng/ml * Regular Menstrual Cycle: 26-35 days * In case of previous use of hormonal contraception: wash-out period of 3 month * Meet standard safety and eligibility criteria for MRI scanning, including the absence of contraindications such as metallic implants, claustrophobia, or other medical conditions that preclude MRI Exclusion Criteria: * History of ovarian surgery * Pathology of the ovaries * Mental health disorders * Use of medication influencing brain function * Ongoing use of hormonal contraception (this would include OCP, but also patches and Mirena containing IUD)