Katja Heuer and Roberto Toro
Brain cells communicate with each other by sending electrical signals that travel down long axons, connecting various parts of the brain. One way to map these connections is by tracking how water molecules move through the brain, a technique called diffusion weighted magnetic resonance imaging (DWI). Water can flow down the length of an axon but can’t penetrate the fatty insulation wrapped around its membrane — by observing which direction water travels, scientists can deduce the path an axon takes through the brain. Using this data, researchers can create complex maps of the interlocking information highways in our heads.