Psilocybin weakens rigid negative beliefs through the REBUS model, allowing new mental patterns to form by increasing brain plasticity and glutamate signaling via 5-HT2A activation. It drives measurable increases in synaptic density and neural rewiring in depression-related brain regions, even in some cases when 5-HT2A is blocked. This shift in thinking patterns helps break entrenched loops like rumination, enabling emotional reset and improved mental flexibility.