This study described in the present protocol consists of two sections. Part A is the first administration into man to evaluate the safety, tolerability and pharmacokinetics of single ascending doses of GSK1144814. The study is a single-blind, randomised, placebo-controlled design in healthy male and female (of non-childbearing potential) subjects. Part B will be an open-label design in healthy male subjects to assess the GSK1144814 neurokinin-1 (NK1) receptor occupancy by positron emission tomography (PET) scanning with [11C]-GR205171