The researchers used MRI and audio recordings to demonstrate that caregiver speech is associated with infant brain development in ways that improve long-term language progress. “Ours is one of two new papers that are the first to show links between caregiver speech and how the brain’s white matter develops.”White matter in the brain facilitates communication between various gray matter regions, where information processing takes place in the brain. Swanson’s team imaged several areas of the brain’s white matter, focusing on developing neurological pathways. This metric for the freedom or restriction of water movement in the brain is used as a proxy for the progress of white matter development. The study’s results align with other recent research showing that slower maturation of white matter confers a cognitive advantage.