4.2.2.1 PCA

## [1] "Intercept"                        "tissue_Brain.BLA_vs_Brain.ACC"   
## [3] "tissue_Brain.CA1_vs_Brain.ACC"    "tissue_Brain.CeA_vs_Brain.ACC"   
## [5] "tissue_Brain.NAc_vs_Brain.ACC"    "tissue_Brain.PrL_vs_Brain.ACC"   
## [7] "treatment_Shocked_vs_Non.Shocked" "drug_Fluoxetine_vs_Vehicle"