Dendritic spines are small, actin-rich structures that protrude from the sides of dendrites, and receive excitatory inputs to the brain. Using a clever piece of video imaging, one group has found that each spine seems like a tiny, writhing sack of actin filaments, struggling to escape. This movement depends on polymerization of the actin, and it may be involved in synaptic plasticity, contributing to the formation of so-called ‘perforated synapses’.