The trial will investigate the effect of the drug JNJ-40346527 on CSF-1R (colony stimulating factor-1 receptor), which is a protein on the outside of cells present in the brain. CSF-1R is responsible for the regulation of various cells, including microglial cells. Recent research suggests that reducing numbers of these microglial cells may be beneficial in slowing the progression of Alzheimer's disease. The Investigators want to see how well JNJ-40346527 is able to block CSF-1R, and in turn suppress these microglial cells. The study is designed to investigate whether or not it is possible to identify changes in levels of proteins which interact with CSF-1R, and changes in the activity or number of affected microglial cells present in the brain. This evidence may provide useful "biomarkers", measures of change in the body, which the Investigators could track to see how the drug is working. These "biomarkers" could then be used in further larger studies to more thoroughly test the benefits of the drug JNJ-40346527. The present study is not designed to test whether or not this drug can slow the progression of Alzheimer's disease.