We bring in two extreme political participants, one Democrat and one Republican, and use MRI and fMRI scans to analyze their amygdala and anterior cingulate cortex (ACC), which studies have shown ...

NARRATION: (MRI SCAN OF LIVING BRAIN ... Dr. Casey zeroed in on the amygdala, an almond shaped node deep in the brain that plays a critical role in processing emotion. NARRATION: (DR. CASEY ...