Studies are currently being done into possible treatments for both symptoms and the overall genetic defects of Down Syndrome, though nothing has currently been approved in humans. One such treatment involves restoring the correct number of the Olig1 transcription factor. Doing this helps the hippocampus express the correct number of inhibitory interneurons and this essentially permanently corrects all cognitive symptoms seen in Down Syndrome, which suggests that the cognitive phenotype in Down Syndrome may actually be reversible. In Ts65Dn mice, memory function was correct using GABAa receptor inhibitors (picrotoxin, bilobalide, and pentylenetetrazole). This still needs to be fully tested in humans, and one such study is being carried out. GABA-A receptor blocker RG1662 has been shown to be safe in a phase I study and is now being studied in a multiclinic study.