Evolving brain-immunity: From Ramón y Cajal’s mysterious butterflies to a garden sustained by immune cells as their nectar

Abstract

Over the last three decades, dogma-breaking studies have refuted the brain’s assumed immune isolation. Echoing Ramón y Cajal metaphor of neurons as “butterflies,” I propose viewing the brain as a neuroimmune garden, with neurons sustained by immune-cell nectar, supporting maintenance, plasticity, protection, and repair.