The Immune System's Hidden Pathway to the Brain For decades, scientists have viewed the brain as a self contained fortress shielded from the rest of the body by an impenetrable barrier.
However, new research from Stanford University is challenging this assumption, revealing that immune cells from the blood can and do flood into the aging brain with alarming frequency.
The study, published in Nature earlier this year, challenges a fundamental concept in neuroscience: that microglia, the brain's specialized immune cells, are established at birth and remain isolated from the rest of the body throughout life.