There’s no evidence yet that this crosstalk between gut fungi and the brain happens in humans, but the possibility would be worth investigating, Olm says. In recent years, evidence has mounted that gut-dwelling bacteria may be able to send signals to the brain via the immune and nervous systems, or by producing substances associated with the symptoms of depression, anxiety, and relaxation. In principle, Olm says, “there’s no reason to think that fungi aren’t doing this as well”. (Read more about how gut bacteria could be influencing the brain).