FOSB and Anxiety: The idea that activity of prefrontal PV+ neurons could regulate state, but not trait, anxiety is supported by the fact that anxiety-like behaviors were observed after 4 weeks of UCMS in the open field in males, without observable changes in PV+ neuron physiology, while anxiety-like behaviors were seen in the EPM test after only 8 weeks of UCMS, a time when we noticed increased numbers of PV/FosB neurons and altered excitability.