After more than a century of study, the significance of brain waves — the coordinated, rhythmic electrical activity of groups of brain cells — is still not fully known. An especially underappreciated aspect of the phenomenon is that waves spatially propagate, or “travel,” through brain regions over time. A new study by researchers at The Picower Institute for Learning and Memory at MIT measured how waves travel in the brain’s prefrontal cortex during working memory to investigate the functional advantages that this apparent motion may produce. “Most of the neuroscience…