Inhibitory Mechanisms of Negative Urgency in Adolescent Suicidal Behavior

Inclusion Criteria: * Ages 13-21 years (inclusive) * Any sex, gender, race, or ethnicity * For participants 18 years of age or older, ability to provide written informed consent * For participants under 18 years of age, ability to provide written assent, with legal guardian's ability to provide written informed consent * Ability of participant (and parent/guardian, if applicable) to read and to communicate verbally and in writing in English (in order to permit comprehensive assessment of suicide risk by study team, and to facilitate safety planning and mitigation of suicide-related risks as necessary) * Current diagnosis of a unipolar depressive episode (major depressive episode, unspecified depressive disorder, or adjustment disorder with depressed mood), confirmed on the structured diagnostic interview (MINI or MINI-Kid) * For participants in the Dep/SI group: * Any lifetime history of suicidal ideation, as assessed by the Columbia Suicide Severity Rating Scale (C-SSRS) * No prior history of suicidal behavior (interrupted attempt, aborted attempt, or suicide attempt) as assessed by the C-SSRS * For participants in the Dep/SB group: \-- Any lifetime history of suicidal behavior (interrupted attempt, aborted attempt, or suicide attempt) as assessed by the C-SSRS * If the study participant will be completing any of the assessments remotely through the use of video teleconferencing, access to a reliable internet connection will be required Exclusion Criteria: * Imminent suicide risk as determined by the PI or other study board-certified child and adolescent psychiatrist (based on review of C-SSRS and SSI scales and clinical assessment of participant) * Current substance use meeting diagnostic criteria for a substance use disorder within the last month on the MINI or MINI-KID diagnostic interview (with the exceptions of caffeine and nicotine) * Lifetime history of psychosis, hypomania, or mania * Historical diagnosis of autism spectrum disorder or intellectual disability * Antiepileptic medication use or chronic benzodiazepine use (as-needed benzodiazepine use will be permitted if it can be held on day of study visit with TMS-EEG testing) * Pregnancy or suspected pregnancy in participants capable of becoming pregnant (assessed with urine pregnancy test) * Medical/neurologic history that would pose increased risks for transcranial magnetic stimulation (TMS) or magnetic resonance imaging (MRI), or factors that would impede completion of study procedures, including: * Neurological disorders including seizure disorder, history of anoxia, history of head injuries with loss of consciousness for greater than 5 minutes * Suicide attempt by hanging or strangulation (asphyxiation) leading to anoxia * Any personal history of seizure or family history of epilepsy * Any metallic implants, fragments, or devices * Any cardiac pacemaker, medication pump, neural stimulator, or other implanted medical device * Risk for increased intracranial pressure (e.g., history of intracranial mass) * History of intracranial surgical procedure * Any contraindication to TMS determined by the TMS Adult Safety Screen (TASS) * Any contraindication to MRI identified on imaging center screening form * Any non-removable hair, head, or neck body modifications that would impede TMS and proper EEG recording