A Study To Assess the Effects Of PF-04457845 On BOLD fMRI In Subjects With Post Traumatic Stress Disorder

This is a Phase II, randomized, placebo-controlled, parallel group design study in male and
female subjects with moderate-to-severe Post Traumatic Stress Disorder between the ages of
18 and 60 years old. During this study, a dose of 4 mg PF-04457845 will be administered in
the morning on Days 1-7. On Each subject will undergo a resting state fMRI (pre and post and
day 8), a fearful vs. neutral faces fMRI task and a fear extinction fMRI paradigm. The
Emotional Faces Paradigm and resting state tasks will be performed on Day 1 (prior to drug
or placebo) and on Day 8. Acquisition of fear conditioning will be performed during the
first imaging session on Day 1. After the first imaging session on Day 1, subjects will
complete behavioral rating scales and then be dosed. Approximately six hours after dosing
subjects will re-enter the scanner and perform the fear extinction paradigm. On Day 2,
subjects will perform the fear extinction memory retention task within the scanner. Further
physiological monitoring, including skin conductance and heart rate, will take place during
the fear extinction paradigm. One safety follow-up visit will occur between Days 11-18.

Inclusion Criteria:

- Men and women 18-60 years of age with a primary psychiatric diagnosis of Post
Traumatic Stress Disorder

Exclusion Criteria:

- Other psychiatric illness requiring current treatment with medication.