Inside a synesthete's head: A functional connectivity analysis with grapheme-color synesthetes

► 18 grapheme-color (GC) synesthetes are investigated using event-related fMRI. ► Left inferior parietal more active when synesthetes perceive letters. ► Left inferior parietal cortex is functionally stronger connected to V1 in synesthetes. ► Communication between parietal cortex and V1 is important in GC synesthesia.