This is an image of an entire cleared mouse brain which shows Interleukin-1 Receptor 1 [removed] IL-1R1, green) throughout the vasculature of the brain. IL-1R1 is a receptor that detects proinflammatory molecules during health and inflammation. Through blood vessels, it is well known to induce the classical behaviors associated with sickness such as fever, lethargy, anhedonia and social isolation. Understanding how IL-1R1 on blood vessels is distributed tells us about how IL-1R1 signaling changes brain activity and behavior.