Using in vivo imaging technology, investigators at the University of Utah and the University of Padua have identified a new signaling mechanism for glutamate that was linked to the onset of spreading depression or spreading depolarization, a neuronal activity pattern that plays a role in multiple neurological disease states. In mouse models of migraine, glutamate, which is the major excitatory neurotransmitter of the brain, was released in what the authors called "plumes" or puffs.