INCLUSION CRITERIA:  In order to be eligible to participate in this study, an individual must meet all of the following criteria:  Clinic and fMRI:  Provision of signed and dated informed consent form Male or female, aged 18-50, inclusive Patients only: Primary DSM5 diagnoses of an anxiety disorder (GAD, SAD, panic disorder)  EXCLUSION CRITERIA:  Clinic and fMRI:  An individual who meets any of the following criteria will be excluded from participation in this  study:  Non-English speaking individual Pregnancy or positive pregnancy test Any significant medical or neurological problems as determined by investigators (e.g. cardiovascular illness, respiratory illness, neurological illness, seizure, etc.) Current use of medications that pass the blood brain barrier and act on histamine (i.e. diphenhydramine), dopamine (methylphenidate), norepinephrine (buproprion), serotonin (sertraline), or acetylcholine (amitryptiline) receptors. Subjects will be excluded if they take these medications on a chronic basis. Subjects will be included if they have not taken the medication for five half-lives prior to a study visit. Current or past serious mental disorders (e.g., bipolar or psychotic disorders) (except for anxiety and depressive disorders in patients) Current alcohol or substance use disorder History of moderate or severe alcohol or substance use disorder within one year prior to screening Current psychotropic medication use. Anxiolytic medications are allowed if they are taken on an as needed basis and the subject has not taken the medication for five halflives prior to a study visit. Current or past significant organic central nervous system disorders as determined by investigators, including but not limited to seizure disorder or neurological symptoms of the wrist and arm (e.g., carpal tunnel syndrome) for shocks to be delivered on affected arm. Positive urine toxicology screen at screening visit under 01-M-0254 Employees of NIMH or an immediate family member of a NIMH employee.  fMRI study only: Any medical condition that increases risk for fMRI:  Any metal implants (clips, screws, plates, pins, etc) that are not deemed to be MRI safe Any sort of medical implants that are determined to be not safe for MRI (aneurysm clips, pacemaker, insulin pump, Hickman line, etc.) Certain types of IUD and other implants are allowable if they are determined to be safe for MRI. Permanent makeup and tattoos above the neck Patients who have difficulty lying flat on their back for up to 120 min in the scanner Healthy volunteers only: Current DSM-5 disorders.