Brain time-activity curves (TACs). (a) Brain TACs plotted in logarithmic scale of individual monkey of baseline and poly I:C treatment scans. Brain concentrations normalized with injected radioactivity (ID) and body weight. The inset graph corresponds to TACs at early post-injection times (0 to 3 min). (b) The time courses of brain-to-plasma radioactivity concentration ratio are plotted individually. The symbols and lines correspond to individual animals and conditions as in Figure 4.