Inhibitory Mechanisms of Negative Urgency in Adolescent Suicidal Behavior

The goal of this study is to understand why some people act more impulsively when feeling negative emotions, which is called negative urgency. The researchers hope to understand how negative urgency relates to the way networks of brain cells communicate with one another. The researchers will measure negative urgency and brain signals in adolescents aged 13-21 years with depression and suicidal thoughts and behaviors. The main questions it aims to answer are: * Whether a type of brain signaling called cortical inhibition is related to negative urgency * Whether depressed adolescents with suicidal behavior have more problems with cortical inhibition than depressed adolescents with suicidal thoughts only * Whether the relationship between negative urgency and cortical inhibition changes over time Adolescents who participate in the study will complete the following activities at the time they join the study, as well as 6 months and 12 months later: * Interviews with researchers and questionnaires to learn about their thoughts, emotions, and symptoms * A questionnaire about impulsive behaviors and negative urgency * Computerized games that measure brain functions * An MRI scan of the brain * Transcranial magnetic stimulation with electroencephalography (TMS-EEG), a way to measure how brain cells communicate (cortical inhibition) using a magnet placed outside of the head and recording brain signals