Brain Stimulation and Decision-making

Inclusion Criteria: * Provides written informed consent * Fluent English speaker * Absence of current drug use as assessed by subject history and/or urine drug screen Exclusion Criteria: * Pregnant or currently breastfeeding 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 fMRI 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 Facility for Research and Education in Neuroscience (FERN) * Unable to fit comfortably in the scanner * Contraindication to TMS, including history or family history of epilepsy, metallic implants in the head and/or neck, brain stimulators, vagus nerve stimulators, ventriculoperitoneal (VP) shunt, pacemakers * Current use of medications that may increase the risk of seizures (e.g., bupropion, varenicline, chlorpromazine, theophylline) or reduce the effects of rTMS, such as benzodiazepines * History or current serious or unstable medical illness, including cardiovascular, hepatic, renal, respiratory, endocrine, neurologic, or hematologic disease, as assessed by subject history * Not right-handed as assessed by the Chapman handedness inventory or self-report * History of head injury resulting in more than a brief loss of consciousness, as assessed by subject history * History of cocaine or stimulant use (e.g., amphetamine, cocaine, methamphetamine), as assessed by subject history * History of use of dopaminergic drugs (including methylphenidate or other stimulant medication), as assessed by subject history * Current use or more than occasional use in the past year of tobacco products, including cigarettes, e-cigarettes, cigars, snuff, and chewing tobacco, or nicotine replacement products such as gum or patches, as assessed by subject history * Evidence of significant inconsistencies in self-report measures Additional Exclusion Criteria for Optional Ecological Momentary Assessment (EMA)Component for Subject Safety * Anything above minimal risk for suicide, as assessed during the clinical interview (SCID) at screening and the Columbia Suicide Severity Rating Scale (C-SSR). C-SSRS risk will be assessed as any score \> 3. * Any physical or neuropsychiatric conditions that may worsen/or prevent walking or running. Additional Exclusion Criteria for Optional Ecological Momentary Assessment (EMA)Component for Data Quality * Meet criteria for current psychotic disorders, bipolar disorders, or severe substance use disorders as assessed by the Mini International Neuropsychiatric Interview. * Used psychotropic medications within the last six weeks as assessed by subject history. Additional Exclusion Criteria for Participants with Major Depressive Disorder: * Anything above minimal risk for suicide, as assessed during the clinical interview (SCID) at screening and the Columbia Suicide Severity Rating Scale (C-SSRS) * A symptom severity score of at least 11, as assessed by the Beck Depression Inventory (BDI)-II * History or current diagnosis of any of the following Diagnostic and Statistical Manual of Mental Disorders (DSM)-IV psychiatric illnesses: * Organic mental disorder * Schizophrenia spectrum disorders * Delusional disorder * Psychotic disorders not otherwise specified * Patients with mood-congruent or mood-incongruent psychotic features * Patients with bipolar mood disorders * Substance dependence * Substance abuse within the last 12 months (except cocaine or stimulant abuse), which will lead to exclusion * Absence of any psychotropic medications for at least 2 weeks. No patient will be asked to discontinue or otherwise interrupt any psychotropic medications to participate in this study. The listed "washout" periods are only applicable for patients who previously used psychotropic medications, but recently decided to discontinue their use for some other reason. * 6 weeks for fluoxetine * 6 months for neuroleptics * 2 weeks for benzodiazepines * 2 weeks for any other antidepressants Additional Exclusion Criteria for Healthy Controls: * Any current or past history of any DSM-IV psychiatric illnesses, presence of a DSM-IV psychiatric disorder within a first-degree relative, or current or past use of psychotropic medications * Score no greater than 10 on the BDI-II * Score \> 1 on the SHAPS