Reader Ostracus informs us of research led by Michael Ehlers of Duke University that has identified a molecule, myosin Vb (five-b), that seems to be a critical component in the formation of memory. "A major puzzle for neurobiologists is how the brain can modify one... synapse at a time in a brain cell and not affect the thousands of other connections nearby. Plasticity, the ability of the brain to precisely rearrange the connections between its nerve cells, is the framework for learning and forming memories ... The discovery of a molecule that moves new receptors to the synapse so that the neuron... can respond more strongly helps to explain several observations about [brain] plasticity ... [The researchers] found that the myosin Vb molecule in hippocampal neurons responded to a flow of calcium ions from the synaptic space by popping up and into action. One end of the myosin is attached to meshlike actin filaments so it can 'walk' to the end of the nerve cells where receptors are. On its other end, it tows an endosome, a packet that contains new receptors. 'These endosomes are like little memories waiting to happen,' Ehlers said."