Ayahuasca is a DMT-containing plant medicine with a long history of Indigenous use in the Amazon basin, gaining attention for its potential in treating mental health problems including PTSD. Ayahuasca retreats, which include a wide range of other plant medicine interventions, remain a subject of limited scientific knowledge, especially regarding their impacts on trauma-related brain changes. Using EEG alongside other psychological and biological measures, Onaya Science conducted a pilot study of the effects of a traditional Shipibo-style retreat on military veterans with PTSD. As well as advancing our understanding of the particular illness and treatment in question, this research demonstrates the value (and difficulties) of bringing neuroscience beyond the lab into naturalistic settings, such as the Amazon rainforest, where opportunities are ripe for translating traditional knowledge practices into conventional Western science.