In this study, researchers at the Max Planck Florida Institute for Neuroscience (MPFI) study neurons by controlling their activity using light. The researchers want to know how long learning takes. Our brain learns and adjusts our understanding through a process called structural plasticity, through which individual neurons in our brains strengthen important connections and weaken less important ones. The structural plasticity of dendritic spines is a fundamental mechanism of the brain’s ability to learn and remember, a process known as long term potentiation (LPT). So how long does LPT take? In this study, researchers devise a unique light-based process to discover the answer. They use a protein known to play an essential role in learning and memory to stimulate the LPT process and find that the protein needs to be active for only a very short time, one minute or less, for successful LTP and animal learning.