The researchers found that chronic isolation leads to an increase in Tac2 gene expression and the production of NkB throughout the brain. However, administration of a drug that chemically blocks NkB-specific receptors enabled the stressed mice to behave normally, eliminating the negative effects of social isolation. Conversely, artificially increasing Tac2 levels and activating the corresponding neurons in normal, unstressed animals led them to behave like the stressed, isolated animals.