Inclusion Criteria:
* Females of all races and ethnic origins
* Ages from 20 to 32
* Right-handed
* Capable of providing written informed consent
* Currently unmedicated. Note that this criterion applies at enrollment only, and subjects will be informed that they can continue to be in the study if they begin a new medication after enrollment.
* Normal or corrected-to-normal vision and hearing
* Fluency in written and spoken English
* Absence of first-degree relatives with a history of a psychotic disorder or psychotic symptoms; (adopted individuals are eligible to participate but we will probe about family history in case such information is available to the adopted subject)
Exclusion Criteria:
* Participants with suicidal ideation where continued study participation is deemed unsafe by the study clinician (these participants will be immediately referred to appropriate clinical treatment)
* Pregnant women, or women of childbearing potential who have a positive result on a urine pregnancy test
* Failure to meet MRI safety requirements including but not limited to any metal implants or prostheses that cannot be removed, or exposure to shrapnel
* Claustrophobia or severe anxiety that might impact participation in neuroimaging
* Injury or movement disorder that may make it difficult to lie still in the scanner
* Any current recreational/illicit drug use as assessed by a urine drug test (covering cocaine, cannabinoids, opiates, amphetamines, methamphetamines, phencyclidine, MDMA, benzodiazepines, methadone, oxycodone, tricyclic antidepressants, and barbiturates)
* Use of drug or herbal supplement for depression (e.g., St. John's Wort or SAMe) of those that could affect stress response
* Use of any medication in the 24 hours prior to the Scanning procedure (including antibiotics, asthma inhalants, pain relievers, antihistamines, or over-the-counter medications).
* Recent use (within 3 weeks) or any medication that affects blood flow or blood pressure, or which is vasodilating/vasoconstricting
* Use of Melatonin within 5 days of the Scanning procedure
* Metformin use in the past 6 months (for either clinical care or as part of research)
* Serious or unstable medical illness, including cardiovascular, hepatic, renal, respiratory, endocrine (hypothyroidism), neurologic, autoimmune disease (such as Lyme, Crohn's), or hematologic disease
* Current infectious illness (either transient or chronic); Current episode of allergic reaction or asthma
* Hemophilia; Diabetes with poor glucose control; History of chronic migraine (\> 15 days/mo.); History or current diagnosis of dementia
* History of seizure disorder
* Any history of significant head injury or concussion
* Past/current DSM-5 diagnosis of: OCD, ADHD, schizophrenia, schizoaffective disorder, delusional disorder, psychotic disorders NOS, bipolar disorder, patients with mood congruent or mood incongruent psychotic features, autism or any other pervasive developmental disorder, organic mental disorder, anorexia, binge eating disorder or bulimia (however a history of bulimia or binge eating disorder is allowable if it has been in remission for at least two years)
* History of moderate or severe substance or alcohol use disorder; or, mild substance or alcohol use disorder within the last 12 months (with the exception of cocaine or stimulant abuse, which will lead to automatic exclusion).
* History of ECT
* Patient is clinically unstable, in the judgment of the clinician
