This image shows densely accumulated dendritic spines. Researchers from Kyushu University discovered a previously unrecognized synaptic “hotspot” that forms during adolescence, challenging the long-held view that adolescent brain development is driven mainly by synaptic pruning. Credit: Takeshi Imai / Kyushu University Adolescence is a defining stage not only for social and physical growth, but also for how the brain develops. During this time, advanced mental abilities such as planning,