CHICAGO, ILLINOIS—When prairie voles choose a mate, there’s no turning back—the “love chemical” oxytocin increases in their brains and they devote themselves to only each other. Although scientists have observed the behavioral and chemical side of prairie vole love, the neural networks behind commitment are still a mystery. Now, a group of scientists are working toward clearing up the neuronal backdrop of long-term love, and yesterday, presented their findings here at the annual meeting of the Society for Neuroscience. Studies have long suggested the nucleus accumbens, a part of the brain involved in reward processing, plays a crucial role in this type of devotion. To get a better look at the neuronal activity of this region, the scientists mounted a small-scale microscope that monitors calcium flux on top of a male prairie vole’s head (the more calcium into the neuron, the more neuronal activity). They saw that when male prairie voles interacted with their special lady vole, neuronal activity in the nucleus accumbens jumped 20% compared with when they interacted with a random female. Upon closer inspection, scientists saw that specific neurons that fired when the voles interacted with their mates stayed silent when they interacting with a different female. The result, though preliminary, indicates that mates stimulate the brain’s reward center in ways that nonmates cannot.