Neuromodulation of the Fear Extinction Circuit Using Temporally and Anatomically Specific TMS in Humans

Inclusion Criteria:

* Willing and able to provide informed consent.
* Inclusion Criteria for PTSD Subjects - Diagnosis of current PTSD
* Inclusion Criteria: Healthy Controls (HC) - no current psychiatric disorders ("Axis I" disorders)

Exclusion Criteria:

* Lifetime history of seizure or significant head trauma or other significant neurologic disease (e.g., tic disorder)
* History of serious/significant psychiatric diagnoses ("Axis I" diagnoses)
* Current significant suicidal ideation, plan or intent or suicidal behavior in past 6 months based on CSSRS and clinical judgment or Self-injurious behavior that involves suicidal intent, requires medical attention, or occurs daily
* Use of neuroleptics within one year prior to study
* Current substance use
* Pregnancy (to be ruled out by urine β-HCG).
* Metallic implants or devices contraindicating magnetic resonance imaging.
* Currently taking medications that lower the seizure threshold. These include antipsychotics, high dose theophylline or stimulants such as methylphenidate. Patients taking bupropion must be on a stable dose (\*last 3 months) and take less than or equal to 300 mg/day.
* Implanted devices in subject's head (shunts, cochlear implants); metal in subject's head (other than dental implants).
* 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 Healthy controls (HC) group: Current psychiatric diagnosis ("Axis I" diagnosis)