The hippocampus, a skinny log of brain tissue tucked in deep above your ear, is the star of memory research. People with damaged hippocampi — such as the famous patient Henry Molaison, known as H.M. — can’t make new memories. And studies in rodents have shown that creating new memories drives robust connections between neurons in the hippocampus.

Despite getting all the attention, the hippocampus doesn’t act alone. Our memories are as good as they are only because of the way the hippocampus talks to the rest of the brain. A study published this week in the Proceedings of the National Academy of Sciences underscores the importance of hippocampal interactions with the prefrontal cortex, the