This study aims to test whether aerobic exercise performed after fear extinction learning improves cognitive, physiological, and neural indices of extinction recall in a sample of trauma-exposed men and women with and without posttraumatic stress disorder (PTSD). Participants will complete a clinical intake visit (Day 0), followed by a three-day fear conditioning (day 1), fear extinction + activity (day 2), and fear extinction recall (day 3) protocol.

Inclusion Criteria for PTSD:

• male or female sex
• right-handed
• age 18-64
• a current diagnosis of PTSD where the index event involves interpersonal violence exposure (e.g., physical/sexual assault).

Inclusion criteria for the trauma-exposed (without PTSD) control participants includes:

• male or female sex
• right-handed
• age 18-64
• interpersonal violence exposure (e.g., physical/sexual assault).

Exclusion Criteria for all participants:

• current substance use disorder (other than alcohol, nicotine, or cannabis)
• acute suicidality
• history of bipolar/psychotic disorder
• changes to or addition of psychiatric medication in the past 4 weeks (6 weeks for fluoxetine)
• medications that effect neurovascular properties upon which BOLD fMRI capitalizes (e.g., water pills)
• history of neurological disorders or disease (e.g., traumatic brain injury, epilepsy, seizures)
• loss of consciousness > 10 minutes
• intellectual disabilities (IQ<70)
• developmental disorders
• MRI contraindication (e.g., internal ferromagnetic objects such as electronic devices, surgical implants, shrapnel; see phone screen)
• claustrophobia or the inability to lie still in a confined space
• physical disabilities that prohibit task performance (e.g., blindness or deafness)
• positive pregnancy test
• cochlear implant
• an implanted neurostimulator
• physical disabilities that prohibit task performance (e.g., blindness or deafness)
• vulnerable populations (i.e., pregnant women, individuals appearing to lack consent capacity, prisoners, individuals unable to read consent materials, individuals in a relationship with study researchers (e.g., friends, family members, significant others)
• having a history of chest pain during physical activity
• having a bone, joint, cardiac, or other medical condition that a doctor has said may be worsened by physical activity
• having asthma
• responding 'Yes' to any of the seven questions on the Physical Activity Readiness Questionnaire (PAR-Q - administered as part of the Exercise Safety Questions of the phone screen), indicating it is unsafe for the individual to engage in aerobic exercise without physician approval (i.e., potential participant would be eligible to participate if they indicated 'Yes' to one or more of the PAR-Q items provided they obtain a doctor's note indicating it is safe for them to participate in the study)
• Percutaneous Coronary Intervention or acute myocardial infarction in the last 6 weeks
• unstable arrhythmias/implanted cardiac defibrillator shocks in the last 3 months
• any other condition that the PI believes might put the participant at risk.
• Additionally, due to their effects on image quality, interested individuals with the following may be ineligible to participate per PI's judgement: nonremovable dental implants (e.g., braces or upper permanent retainers) as these will distort the MRI images we collect (note: filings, crowns, and silver or gold teeth are okay); any other condition, medication, or implant that the PI believes would degrade image quality or render data unusable