Researchers studied how a specific brain protein called GluN2B affects addiction memories from cocaine use. They found that removing this protein reduced the formation of ‘silent synapses’ – immature brain connections created by cocaine – and weakened drug-related memories. However, this also unexpectedly made mice more active, suggesting that GluN2B normally helps control both addiction memory and activity levels. The findings provide new insights into how addiction memories form and suggest potential ways to treat addiction.