Auto-brewery syndrome is a fairly straightforward example (it has been involved in the acquittal of at least two people so far), but other brain-microbe relationships are likely to be more complicated. We do know a little about one microbe that seems to influence behavior: Toxoplasmosis gondii, a parasite that reproduces in cats and spreads to other animals via cat feces.
some studies have linked infections with the parasite to personality changes, increased aggression, and impulsivity.
Back in 2013, scientists at McMaster University in Canada performed fecal transplants between two strains of mice, one that is known for being timid and another that tends to be rather gregarious. This swapping of gut microbes also seemed to swap their behavior—the timid mice became more gregarious, and vice versa.
