We selected these ROIs for the following reasons: (1) both were found to have a large increase in TSPO following ip LPS treatment, as measured by PET (Fig. 2) and autoradiography (Fig. 3); (2) previous clinical PET studies have shown significant TSPO changes in these two brain areas of patients with neurodegenerative disease and psychiatric disorders (Haarman et al., 2014, Kreisl et al., 2016, Ouchi et al., 2005) and (3) both brain regions are known to have a particularly high microglia density (De Biase et al., 2017, Tan et al., 2020). Here, TSPO is linked to psychiatric disorder.