*2.7. Statistics*

### 2.7.1. General Statistics

Data were expressed as means ± standard deviation (SD) and analyzed using PRISM 7 software (GraphPad, San Diego, CA, USA). Statistical tests and sample sizes are indicated in the figure legends and figures, respectively. Graphs display the mean and error bars represent the SD. The significance between groups is denoted by \* *p* < 0.05, \*\* *p* < 0.01, \*\*\* *p* < 0.001 or \*\*\*\* *p* < 0.0001.

### 2.7.2. Microbiota-Specific Statistics

Statistical analyses were run using the R programming language and software together with the gplots, gdata, vegan (http://cran.r-project.org/package=vegan, accessed on 3 March 2020), ade4, Hmisc, corrplot and phangorn packages. OTU counts were normalized via simple division to their sample size and then multiplied by the size of the smallest sample. α-diversity and richness were estimated using diversity and estimateR. The distance matrix for β-diversity analysis was computed using vegdist and the Bray–Curtis method. Principal

coordinates analysis was computed on a distance matrix using dudi.pco. Associations between the microbiota composition at the genus level, anxiety-like behavior measurements and mononuclear cell percentages were assessed using rcorr. The Kruskal–Wallis rank sum test and post hoc Dunn's all-pairs rank test were used as required to detect differences between groups. *p*-values were adjusted as necessary using false discovery rate correction.
