Neuroimmune Response to Lipopolysaccharide

In this study, healthy adult volunteers will undergo two positron emission tomography (PET) scans using the radiotracer [11C]PBR28 which binds to the 18kDa translocator protein (TSPO). Approximately 3 hours prior to the second [11C]PBR28 PET scan, lipopolysaccharide (LPS; endotoxin) will be administered to evoke a robust neuroimmune response. Subjects will also undergo behavioral and cognitive testing. Vital signs, subjective response, and peripheral cytokine levels will be assayed periodically throughout the experimental session. Specific aims: Quantify the magnitude of neuroimmune response after a classical immune stimulus. Secondary aims: Quantify changes in cognitive function after a classical immune stimulus. Hypothesis: Individuals will exhibit a robust whole-brain neuroimmune response and impaired cognitive function after LPS.