How the gut microbiome shapes learning and memory: A comprehensive review

Cognitive functions, such as learning and memory processes, are closely related to the gut microbiome. The gutbrain axis (GBA), a complex network of bidirectional communications between the central nervous system and the gastrointestinal tract, plays an important role in regulating these functions. This study aims to investigate the impact of the gut microbiome on learning and memory and to provide new insights into the role of the GBA in these cognitive processes. This narrative review explores various mechanisms through which the gut microbiome affects cognitive functions by reviewing scientific articles related to the gut microbiome, GBA, learning, and memory. The focus is on studies that have investigated the relationship between the gut microbiome, changes in microbial composition, and cognitive functions. The results indicate that the gut microbiome influences brain function and behavior through various mechanisms, such as vagus nerve signaling, effects on the enteric nervous system, the production of neurotransmitters, the regulation of inflammation and the immune system, and the production of metabolites such as short-chain fatty acids (SCFAs). Dysbiosis of the gut microbiota affects hippocampal function, learning, and stress regulation. Additionally, probiotics and prebiotics, along with nutritional status, affect the composition and function of the gut microbiome; therefore, maintaining the balance of the gut microbiome and paying attention to the GBA may lead to improved cognitive functions and the prevention of learning and memory-related disorders. Microbiome-based interventions, such as probiotics and dietary changes, have the potential to increase performance.