Fear and Avoidance in PTSD Patients

Inclusion Criteria: 1. 18 - 70 years of age 2. Female or Male 3. Inclusion Criteria: PTSD Subjects a. Diagnosis of current PTSD 4. Inclusion Criteria: Trauma-exposed healthy controls (TEHC) 1. SCID diagnosis consistent with no current psychiatric disorders, and no current PTSD 2. History of trauma exposure 5. Inclusion Criteria: Healthy controls (HC) 1. SCID diagnosis consistent with no current psychiatric disorders ("Axis I" disorders). 2. No history of trauma exposure 6. Willing and able to provide informed consent. Exclusion Criteria for ALL subjects: 1. History of neurologic disease (e.g. tic disorder) 2. Current significant suicidal ideation, plan or intent or suicidal behavior in past 6 months based on CSSRS or Self-injurious behavior that involves suicidal intent, requires medical attention, or occurs daily 3. History of seizure or significant head trauma 4. History of the serious/significant psychiatric diagnosis ("Axis I" disorders) 5. Use of neuroleptics within one year prior to study 6. Current substance use (assessed by urine toxicology; positive urine toxicology screen for any substance, with the exception of THC). Per PI judgement and approval: if urine toxicology is positive for a substance, participant may be eligible to proceed with study provided their urine toxicology (or saliva test for THC) is negative at experimental visit(s) 7. Pregnancy (to be ruled out by urine ß-HCG) 8. Metallic implants or devices contraindicating magnetic resonance imaging 9. High risk of adverse emotional or behavioral reaction, and/or an inability to understand study procedures or the informed consent process Additional exclusion criteria for Trauma-exposed healthy controls (TEHC) group and Healthy controls (HC) group: 10. Current psychiatric diagnosis ("Axis I" diagnoses)