Fig. 7

Alterations in fear memory response and subcellular populations three months after TBI in the setting of gut microbial dysbiosis. a Experimental design. Graphs depict b Richness index and c Shannon diversity index. Mean values are plotted ± SEM, unpaired t-test, *** p < 0.001, n = 3 per group. Fear conditioning 3-day paradigm and quantification of % total freezing time of d conditioning learning, e contextual memory and f cued memory. g Representative images of NeuN + cells in the pyramidal layer of CA3 (indicated by the dotted line) with h stereological quantification and i hippocampi volumes. j Representative images of Iba1 + cells in the injured ipsilateral hippocampi. Scale bars are 250 µm. k Stereological analysis of microglia density as shown in (h). Mean values are plotted ± SEM, unpaired t-test, *p < 0.05, n = 8–9 mice per group. l Representative three-dimensional reconstructive images of microglia (scale bars are 15 um). m-q Quantification of microglia morphology in hippocampi. m Dendrite length, n number of segments, o number of branch points, p number of terminal points and q volume. Abbreviations: VNAM, vancomycin, neomycin-sulfate, ampicillin and metronidazole; CCI, controlled cortical impact. Hip: hippocampus; Amy, amygdala; Cx, cortex