Zapping the brain to understand emotions: a first step

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Male or female * Age 18-55 years * Wechsler Adult Intelligence Scale (WAIS) intelligence quotient (IQ) \>70 * Competent and willing to sign informed consent. * Shall not have been prescribed any standing medications for treatment of a Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) Axis I psychiatric disorders within 90 days of the study and shall not have been prescribed standing opioid analgesic, anticonvulsant, antidementia, antidepressant, antimigraine, antipsychotic, anxiolytic, bipolar agents, central nervous system agents, or sedative/hypnotics within 90 days of the study even if for a non-psychiatric indication. Intermittent use of sedative/hypnotic medications is permitted, but these agents shall not be used within 48 hours of the tIS administration. * Healthy relative to age-dependent expectation as determined by medical history and physical examination within 90 days of enrollment. Exclusion Criteria: * Has a history of an illness, disease, condition injury, or disability which, in the opinion of the principal investigator (PI), may interfere with the completion of all study requirements per protocol, impact the quality of the data, or the validity of the study results. * Contraindication to MRI (e.g. metal implants, claustrophobia, pregnancy) * On the Columbia-Suicide Severity Rating Scale (C-SSRS) Screen Version-Recent, answers YES to Question 3 and NO to Question 6 (Moderate Risk) or answers YES to Question 4, 5, or 6 (High Risk). * Presence or positive history of significant medical illnesses, including high blood pressure(defined as systolic blood pressure (SBP) \>140 or diastolic blood pressure (DBP) \>90, low blood pressure (SBP \<100, DBP \<60), orthostatic blood pressure as baseline (change in mean arterial pressure \[1/3 systolic + 2/3 diastolic\] of \>20%), cardiac illness, or clinical significant abnormal electrocardiogram (EKG), as determined by the site physician * Women of childbearing potential who, at enrollment or during the study: * have a positive urine pregnancy test or a self-reported pregnancy; * are heterosexually active without usage of a medically acceptable, highly effective contraceptive method\* ( 1% pregnancy rate); or * are planning to become pregnant during the course of this study, as determined by the PI, are excluded from study participation. Examples include tubal ligation, vasectomized partner, intrauterine device (IUD) or intrauterine system (IUS), and longacting reversible contraceptives (LARC).