Figure 2.

Effects of inflammation on brain structure and function. (A) Quantitative magnetization transfer imaging study. Brain regions showing a significant increase in magnetization transfer exchange rate constant 3–4 hours after typhoid vaccine–induced inflammation compared with control (saline) injection. Data displayed at a whole-brain corrected threshold of p < .05. Color scale denotes t score. (B) Fluorodeoxyglucose positron emission tomography imaging study. Brain regions showing a significant increase in fluorodeoxyglucose uptake 3–4 hours after typhoid vaccine–induced inflammation; exclusively masked by changes in fluorodeoxyglucose uptake 3–4 hours after placebo (mask threshold p < .005). Data displayed at a whole-brain corrected threshold of p < .05. (C) Left insula voxels showing a significant increase in magnetization transfer exchange rate constant 3–4 hours after experimentally induced inflammation (yellow) overlaid with voxels (green) additionally predicting inflammation-induced fatigue (fatigue visual analog scale, p < .05). (D) Correlation of fatigue visual analog scale scores 4 hours after typhoid vaccine minus placebo (V − P) (x-axis) with inflammation-induced changes in magnetization transfer exchange rate constant of all 1196 voxels within the posterior insula cluster (illustrated in yellow in C) on the y-axis (R² = .2, p < .05). fVAS, fatigue visual analog scale; k_f, magnetization transfer exchange rate constant.