Figure 6. Schematic representing the experimental paradigm for the longitudinal effect of systemic inflammation on cognition. Young (6 months) male Fischer 344 X Brown Norway hybrid rats were either injected with vehicle (n = 16) or LPS (n = 16) once a week for 7 weeks. A subset of animals (vehicle n = 12; LPS n = 12) were cognitively assessed on the spatial discrimination water maze task at 12 and 18 months of age. Hippocampal tissue from behaviorally characterized rats was collected one week after completion of behavioral testing, at 18 months of age, and RNA sequencing was performed on the CA1 region of the hippocampus. The other group of animals (vehicle n = 4; LPS n = 4) were not behaviorally characterized and were used for electrophysiological experiments at 18 months of age (12 months after the injections).