Fig. 4

OI treatment improves POCD in aged mice by modulating neurogenesis. The intestinal contents of aged mice were subjected to an untargeted metabolomic analysis. a Correlation hierarchical clustering heatmap showing the direct correlation between gut flora and metabolites in aged mice among the three groups. b Partial least squares discriminant analysis score plot showing good separation between the sham, POCD, and OI groups. c–f Differentially expressed metabolites were identified by Venn diagram (c), volcano plots (d, e) and heatmap (f). g, h Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis evaluated the enriched pathways for the representative profiles of these differential metabolites. n = 5 for an untargeted metabolomic analysis