The purpose of this research study is to study how the brain learns to avoid certain stimuli or situations using an experimental paradigm. The big goal is to measure brain responses and subject's feelings and expectations when they are learning to actively avoid experimental stimuli, and how fear extinction learning and monetary cost can change how and when subjects are to avoid.

This study aims to study the neural correlates of avoidance learning using a recently validated conditioning and active avoidance paradigm (CAAP). The overarching objective is to measure the neural correlates of active avoidance, and how fear extinction learning and monetary cost modulate these avoidance responses. Participants will include healthy controls (HC), trauma-exposed healthy controls (TEHC), and participants with post-traumatic stress disorder (PTSD). Avoidance is common and often hinders the progression and success of extinction-based exposure therapy in PTSD. The data to be gathered in this study will enable us to probe neural mechanisms of avoidance, extinction, and decision-making to avoid or not, in addition to understanding the impact of cost on avoidance decision-making. These data will provide a more integrated platform for the understanding of the mechanisms of avoidance in both trauma-exposed healthy controls and PTSD psychopathology, which has important implications for treatment.

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)

Individual participant data that underlie the results reported in this article, after deidentification (text, tables, figures, and appendices).

Beginning 9 months and ending 36 months following article publication or as required by a condition of awards and agreements supporting the research.

The investigator who proposed to use the data will have access and give upon reasonable request. Requests should be directed to Mohammed.R.Milad@uth.tmc.edu. To gain access, data requestors will need to sign a data access agreement.