Endotoxin Sickness Insula Resting-State fMRI

This entry covers the resting-state fMRI cohort of a 2016 Brain, Behavior, and Immunity paper by Lekander, Nilsonne and colleagues. Healthy volunteers were randomized, double-blind, to an intravenous injection of 0.6 ng/kg lipopolysaccharide (LPS, endotoxin) or placebo, which triggers a short sickness response in the LPS group. Roughly 2 h 45 min later they were scanned at rest. The authors tested whether connectivity from the anterior and posterior insula to orbitofrontal and cingulate cortex changes during this response and whether it tracks reported symptoms. The fMRI images are not released; eight group t maps are public on NeuroVault.

Composition

52 healthy volunteers were randomized. Resting-state fMRI was available for 48 of them: 28 in the LPS group and 20 in the placebo group. Back pain, headache, nausea and global sickness were rated before and after the injection. Age, sex and the reasons for the four missing scans are not given in the sources reachable without a subscription.

Acquisition

The NeuroVault metadata gives a field strength of 3 T and an eyes-closed resting paradigm. Scanner vendor, sequence parameters, run length and any structural scans are not stated there.

Annotations

The collection holds four seed maps (left and right anterior and posterior insula) of connectivity across both treatment groups, and four endotoxin against placebo maps, one per seed, restricted to an orbitofrontal, anterior and middle cingulate and insula mask. All are T maps in MNI space. The main reported result was stronger coupling between the left anterior insula and the left midcingulate cortex after LPS, which correlated with the rise in back pain.

Known limitations

• Only derived group maps are public; the fMRI images are not shared and have no published terms.
• NeuroVault flags all eight maps as thresholded, and the four contrast maps cover about 2% of the brain.
• The paper is not open access, so demographics and acquisition details could not be checked.