This study will investigate if a new experimental drug to treat Huntington's Disease gets into the brain. If it does get into the brain the study will explore the relationship between the amount of drug in the brain and the amount of drug in the blood. The study will involve healthy male volunteers.

This is an open label, non-randomized, adaptive design PET occupancy study in healthy adult males. The primary aim of this study is to describe the relationship between plasma concentrations and brain PDE4 occupancy of GSK356278 over time. Up to 24 healthy volunteers may be administered single doses of GSK356278 in order to obtain 12 evaluable complete data sets of occupancy estimates. This study will help to optimize the dose selection for future clinical studies with GSK356278.

Inclusion Criteria:

• Healthy male volunteer, aged 22-55 years.
• Normal blood pressure, laboratory values, and body mass index
• Willing to agree to study procedures & contraception requirements
• Capable of giving written informed consent

Exclusion Criteria:

• Any evidence of disease that would preclude participation in the clinical study (includes sexually transmitted diseases, exessive alcohol consumption, and substance abuse).
• Previously involved in another clinical trial within 3 months prior to scheduled administration of study drug
• Smoker
• Suffers from claustrophobia
• Any contraindications for MRI scanning (e.g. pacemaker, metal implants or fillings)

Patient-level data for this study will be made available through www.clinicalstudydatarequest.com following the timelines and process described on this site.