The intestinal microbiome is known as the second human brain because it plays a key role in regulating the central nervous system. New findings show that there is a two-way communication between the gut microbiota and the central nervous system so that this communication network changes and transforms cognition, emotion, social behavior, mental disorders and even personality traits. The mechanisms underlying the effects of gut microbiome on these brain processes have not yet been fully discovered, and there are the many mediators in the connection between the microbes and the gut with the nervous system and the brain. The exact understanding of which. They lead to a better understanding of the microbiome-behavior bond. A thorough understanding of this mechanism is also essential for the use of potential microbial therapies such as fecal transplantation and psychobiotics. In this paper, we first explain the mechanisms of microbial effects on the brain and central nervous system. We will then have a brief overview of research methods. We then look at the role of the gut microbiome in stress, excitement, learning, memory, and social behavior.