This study will determine the safety and tolerability of PF-06649751 given orally to healthy volunteers. To determine the optimal dose for future studies, the concentration of the drug over time will be determined by periodic blood samples. The rate of eye blinks will be measured as an indicator of PF-06649751 action on the receptors of interest in the brain.

Inclusion Criteria:

• Healthy male and/or female subjects of non-childbearing potential between the ages of 18 and 55 years
• Female subjects of non childbearing potential that meet at least one of the following criteria: Achieved postmenopausal status, defined as: cessation of regular menses for at least 12 consecutive months with no alternative pathological or physiological cause; and have a serum follicle stimulating hormone (FSH) level confirming the postmenopausal status; Have undergone a documented hysterectomy and/or bilateral oophorectomy; Have medically confirmed ovarian failure.

Exclusion Criteria:

• Evidence or history of clinically significant hematological, renal, endocrine, pulmonary, gastrointestinal, cardiovascular, hepatic, psychiatric, neurologic, or allergic disease (including drug allergies, but excluding untreated, asymptomatic, seasonal allergies at time of dosing).
• Any condition possibly affecting drug absorption.
• Subjects with epilepsy, or history of epilepsy, or conditions that lower seizure threshold, seizures of any etiology (including substance or drug withdrawal), or who have increased risk of seizures as evidenced by history of EEG with epileptiform activity. Subjects with a history of childhood seizures, and history of head trauma with loss of consciousness requiring hospitalization overnight will be excluded as well.