IFNG and major depressive disorder: In the latter, direct cerebrospinal IFN-γ injection or repopulation of the meninges with IFN-γ-producing T cells reverted the animals’ social behavior to normal by increasing inhibitory γ-aminobutyric acid (GABA)-ergic currents and preventing hyperexcitability in the prefrontal cortex (30).The murine connection between IFN-γ and behavior also extends to humans and seems to be particularly important in the context of depression.