Marked for Destruction

Synapses, the connections between neurons, are far from stable; their strength changes during learning or when we’re exposed to new environments. To avoid becoming overexcited, neurons can weaken these connections by removing particular proteins from synapses. In this image of neurons in a rat hippocampus — a part of the brain involved in learning and memory — enzymes (white and blue dots) mark these unwanted proteins with a tag so that the cell knows to destroy them. Studying this tagging process can help scientists understand how brain cells alter their activity, enabling us to learn and adapt to the world around us.