Scientists always saw the workings of the human mind as separate from the body. Whatever might keep neurons in the brain from sending electrical messages across synapses, experts thought, it had nothing to do with rampant inflammation in the body. But then, science journalist Donna Jackson Nakazawa reports, new research found that microglia, tiny cells viewed as the brain’s janitors, sometimes go rogue. What could this mean for treating mental-health disorders? Original air date: January 16, 2020.