Menstrual Cycle TMS Plasticity Pilot

This project will recruit healthy male and female volunteers between the ages of 20-40. Females must who are not on hormonal medications and, if female, have regular menstrual cycles as defined in Table 1. At time of consent, female participants will be send home with given tests that may assess urine estradiol, LH and/or their metabolites. Participants will be asked to complete these tests at home, will be instructed to use these tests in the morning at the first void of the day; the number of days during each cycle that participants will be asked to complete these tests will be based on their report of their regular cycle pattern but will not be longer than half the number of days in each cycle. In addition, female subjects will be given a RedCap survey link at which they will track their menstrual cycle and results from the urine estradiol/LH tests. Subjects will undergo 4 study visits over approximately 1-2 months depending on availability and, if female, menstrual cycle point. At visit 1, subjects will consent to the protocol, fill out surveys including the TMS Adult Safety Screening (TASS) and a questionnaire about past hormonal medication use and if relevant, menstrual cycle history. If female, subjects will be given take-home ovulation tests to use across the study duration. On the following visits, they may undergo the following procedures: 1) venipuncture to collect approximately 45mL 10 mL of blood 2) motor threshold testing, 2) Paired-Pulse Stimulation 3) Single-Pulse TMS to the motor cortex 4) intermittent Theta Burst Stimulation (iTBS) to the motor cortex.