Search for Novel Transcranial Magnetic Stimulation (TMS) Targets for Mental Illness

Inclusion Criteria: * Age 18-65 * English proficiency sufficient for informed consent, questionnaires/tasks, and treatment * Primary diagnosis of one of the following: major depressive disorder (MDD), obsessive-compulsive disorder (OCD), generalized anxiety disorder (GAD), or schizophrenia (determined by focal assessment using the Structured Clinical Interview for DSM-5) * ≥20 on the Beck Depression Inventory for patients with MDD * ≥16 on the Beck Anxiety Inventory for patients with GAD * ≥16 on the Yale-Brown Obsessive-Compulsive Scale for patients with OCD * ≥58 on the Positive and Negative Symptom Scale for patients with schizophrenia * Stable psychotropic medication regimen, or remain medication free, for 4 weeks prior to treatment (Medication changes during study enrollment period will be tracked for post hoc analysis). * Primary clinician (e.g. psychiatrist, therapist, psychologist, APRN, PA, etc.) responsible for psychiatric care before, during, and after the trial Exclusion Criteria: * Active pregnancy as determined by a urine pregnancy test * Cluster B personality disorders (antisocial personality disorder, borderline personality disorder, histrionic personality disorder, narcissistic personality disorder) * PTSD with active, clinically significant symptoms, as determined by clinician * Diagnosis of Schizoaffective Disorder, Bipolar Type * Recent (within 4 weeks) or concurrent use of rapid-acting antidepressant agent (ketamine/esketamine/ECT) * Ferromagnetic metallic implant that would contraindicate receiving TMS or obtaining MRI * Any other TMS or MRI safety concerns identified by the clinician * Receiving or planning to receive other TMS treatments during course of participation * History of: * Neurosurgical intervention for mental illness * Moderate to severe autism spectrum disorder * Intellectual disability * Severe cognitive impairment * Significant neurological illness (e.g., dementia, Parkinson's, Huntington's, brain tumor, seizure disorder, subdural hematoma, multiple sclerosis) * Untreated or insufficiently treated endocrine disorder * Eating disorders * Treatment with investigational drug or intervention during the study period * Current evidence of: * Mania or hypomania * Active suicidal ideation or a suicide attempt within the past year * Contraindications to either TMS or MRI (e.g., metallic implants, etc.). * Current moderate or severe substance use disorder or demonstrating signs of acute substance withdrawal * Significantly increased seizure risk as determined by a clinician * For participants with schizophrenia: * Evidence of impaired capacity to consent, e.g. impaired insight into illness, as deemed by a licensed psychiatrist or psychologist on the study team * Hospitalization with psychosis in the past 6 months * Positive urine drug screen for illicit substances * Existing tinnitus (ringing in the ears) * Any other condition deemed by the PI to interfere with the study or increase risk to the participant