Understanding the cellular and molecular mechanisms underlying brain plasticity (how the brain can learn, develop and reorganize itself) is crucial for explaining many illnesses and conditions. Neurocientists from the University of Göttingen and University Medical Center Göttingen (UMG) have now managed to repeatedly image synapses, the tiny contact sites between neurons, in awake adult mice. They are the first to discover that adult neurons in the primary visual cortex with an increased number of ‘silent synapses’ (ie newly formed synapses that are inactivated), lacking a certain protein (PSD-95), display structural changes that were previously only reported in young mice. This research by the Collaborative Research Centre CRC889 was published in PNAS.