There’s an old saying in neuroscience: neurons that fire together wire together. This means the more you run a neuro-circuit in your brain, the stronger that circuit becomes. Your brain’s microglial cells 'prune' your synaptic connections.This is the fascinating way that your brain makes space to build new and stronger connections so you can learn more. Your brain cleans itself out when you sleep. In fact, you actually have some control over what your brain decides to delete. It's the synaptic connections you don’t use that get marked for recycling. The ones you do use are the ones that get watered and oxygenated. So be mindful of what you’re thinking about.