Impact of Estrogen on Fear Extinction R61

Inclusion Criteria: * Right-handed (Edinburgh Inventory - Oldfield 1971). * SCID diagnosis consistent with none, current or past history of Axis I psychiatric disorders. * To be matched for age, gender, and years of education, as well as self-identified race/ethnicity. * For naturally cycling female subjects, stage of menstrual cycle will be ascertained by history, and by serological measures. * For women on oral contraceptives, we will identify those using 20mcg ethinyl, 2nd or 3rd generation, monophasic Exclusion Criteria: * Psychiatric, neurologic or medical condition that would interfere with study procedures or confound results, ascertained by history. * History of seizure or significant head trauma (i.e., extended loss of consciousness, neurological sequelae, or known structural brain lesion). * History of Axis I psychiatric diagnosis; e.g., history of substance use disorder, psychotic disorder, bipolar disorder, tic disorder, or eating disorder. * Use of psychotropic medication within 4 weeks prior to study (within 6 weeks for fluoxetine, or other long-lived compounds; within one year for neuroleptics). * Pregnancy (to be ruled out by urine ß-HCG). * Metallic implants or devices contraindicating magnetic resonance imaging. * Use of oral contraceptives or non-oral contraceptives containing estrogen and progesterone within 3 months * History of breast cancer. * Allergy to peanut oil.