One common psychotherapy treatment for helping people overcome traumatic memories is to have them revisit the events in a safe environment so that their brains can replace the memories with less upsetting ones. But this strategy works only with recent trauma. Researchers led by MIT’s Li-Huei Tsai report that histone deacetylase inhibitors may help make this psychotherapy treatment an option for people with older traumas, if results in mice translate to humans (Cell 2014, DOI: 10.1016/j.cell.2013.12.020). Tsai’s team worked with a mouse model of posttraumatic stress disorder, which is induced when mice hear a tone and then experience an electric shock. Eventually, the mice freeze in fear when they just hear the tone. Researchers previously discovered that histone deacetylase inhibitors help activate genes important for learning and memory. When the team fed the animals a common benzamide-based histone deacetylase inhibitor called CI-994, the animals were able to disassociate the sound of the tone from fear of an imminent shock—effectively rewriting an upsetting memory.