Researchers found that mice treated with a wide range of doses of psilocybin “acquired a robust conditioned fear response.” The fear response went away faster at lower doses compared to higher doses and mice given saline control doses. The study also found no change in the number of newborn neurons in the hippocampus of the mice in any of the treatment groups, indicating “fear conditioning” occurs elsewhere in the brain. The authors propose psilocybin may be useful for treating PTSD and other conditions.