This is the first study in Humans with GSK424887 to evaluate what effects, good or bad, the drug has on human health (safety and tolerability) and the amount of drug which gets into the bloodstream and is eliminated from the body (pharmacokinetics). Also the study aims to investigate the penetration of the drug in the human brain by using PET (Positron Emission Tomography) imaging technology

Inclusion Criteria:

• Healthy males aged 18-45 years, limited to 25-40 years for PET section

Exclusion Criteria:

• The subject has a positive: drug/alcohol, Hepatitis, HIV screen
• The subject has a history of psychiatric illness suicidal attempts or behaviour.
• Abuse of alcohol.
• Clinically significant laboratory, ECG abnormality;
• The subject has recently received an investigational.
• Use of prescription or non-prescription drugs,
• History or presence of allergy to the study drug or drugs of this class,.
• Donation of more than 500 mL blood within the 90 days before dosing.
• An unwillingness of male subjects to comply with contraceptive requirements
• Average daily caffeine intake exceeding Protocol requirements.