Temporal Interference in Psychiatry (TIP): Neuromodulation Using Temporal Interference

Inclusion Criteria:

* Written informed consent.
* Fluent English speaker.
* Both sexes and all ethnic origins, between 18 and 65 years old.
* Absence of current moderate to severe illicit drug use as assessed by subject history (AUDIT\>=8 and/or DAST\>2).

Exclusion Criteria:

* Pregnant or currently breast-feeding women or any woman of childbearing potential who is seeking to become pregnant or suspects that she may be pregnant, as assessed by subject report and/or urine pregnancy screen.
* Contraindications to MRI scanning (including presence of a cardiac pacemaker or pacemaker wires, metallic particles in the body, vascular clips in the head or previous neurosurgery, prosthetic heart valves, claustrophobia, as assessed with the standard MRI screening form from the CABI, FERN or CSI.
* Unable to fit comfortably in the scanner.
* Contraindication to TI and/or TMS (including history of epilepsy, metallic implants in the head and/or neck, brain stimulators, vagus nerve stimulators, VP shunt, pacemakers)
* Current use of medications that may increase the risk of seizures (e.g., bupropion, varenicline, chlorpromazine, theophylline).
* History or current serious or unstable medical illness, including cardiovascular, hepatic, renal, respiratory, endocrine, neurologic or hematologic disease, as assessed by subject history.
* History of head injury resulting in more than brief loss of consciousness, as assessed by subject history.
* Current cocaine or stimulant use (e.g., amphetamine, cocaine, methamphetamine), as assessed by subject history.
* Evidence of significant inconsistencies in self-report measures.
* Non-English speakers will be excluded from this study because the research procedures rely heavily on the administration of validated self-report questionnaires, clinical interviews, and task instructions that at this time, are only available in English. Additionally, study staff are trained to administer these assessments and obtain informed consent in English only. Including non-English speakers would therefore pose a risk of misunderstanding study procedures, consent materials, or questionnaire items, which could affect both participant comprehension and data integrity.