The Microbiota-Gut-Brain Axis as a Fundamental Regulator of Neuroplasticity: A Systematic Review and Meta-Analytic Synthesis

<span style="font-weight: 400;">The classical neurocentric view of the central nervous system (CNS) as an isolated, immune-privileged entity has been superseded by a systemic paradigm acknowledging the profound influence of peripheral systems on neural function. Central to this paradigm shift is the microbiota-gut-brain axis (MGBA), a bidirectional communication network linking the enteric environment with the cognitive and emotional centers of the brain. Neuroplasticity&mdash;the brain's intrinsic capacity to reorganize structural and functional connectivity in response to stimuli&mdash;is now understood to be heavily modulated by signals originating from the gut microbiome. Dysbiosis, or the maladaptive alteration of microbial communities, is increasingly implicated in the pathophysiology of neurodegenerative and psychiatric disorders characterized by deficits in synaptic plasticity, neurogenesis, and circuit refinement.</span>