Abstract
How the mammalian brain processes information, stores memories and maintains homeostasis depends on the dynamic communication between neurons, glia cells, blood vessels and many other cell types via signaling molecules such as neurotransmitters, neuropeptides and hormones throughout the entire brain. Currently no technology can measure brain-wide molecular signaling with sufficient spatial and temporal resolution in living mammals, which poses a major roadblock for understanding molecular foundations of brain function and dysfunction in disease states.