The brainstem contains the foundation for all other functions in the brain and body. It takes care of everything our bodies do on autopilot, from breathing and heart rate to physiological stress responses and sleep patterns. When it has experienced trauma, the brainstem learns that it must keep the mind and body on high alert.

As children move through the world and encounter different experiences—challenges, victories, other humans large and small—their amazing, flexible brains will be wiring new connections, pruning old pathways that aren’t used much, making associations, and learning what they can and can’t take for granted about reality. When older babies and young toddlers go through that endearing phase of dumping everything out and throwing all their food on the floor, they are learning somet