146. Effects of low-dose LPS on resting-state fMRI network activity

Abstract

Brain areas involved in emotional regulation have been shown to be sensitive to experimental inflammatory stimulation with LPS (lipopolysaccharide) during task based fMRI. However, it is not known how LPS affects the brain at rest, which is relevant for understanding how inflammation affects the general condition of an individual. In a randomized study, we injected 0.6 ng/kg LPS or placebo in 50 healthy humans. Subjects were instructed to relax with closed eyes during resting-state fMRI for 8 min. Independent component analysis revealed 25 components, 20 of which were judged to represent physiologically meaningful brain networks. Of these 20 networks, 3 showed greater strength in the endotoxin condition: a cerebellar network (peak level p < 0.01; cluster-level corrected p = 0.027), a primary visual network ( p < 0.01, corrected p = 0.041), and an insular network ( p < 0.01, corrected p = 0.066). The latter network is of particular interest in this context since the insula is thought to subserve integration of interoceptive stimuli. Thus, tentative evidence is presented for increased insular functional network activity during resting-state fMRI as a result of LPS stimulation, possibly due to increased processing of interoceptive stimuli related to sickness experience.