A yellow line indicates the track of a rat demonstrating spatial memory on a rotating disc. The animal avoids the stationary sector where it had been shocked the previous day. Inhibition of the persistent kinase that maintains long-term potentiation at hippocampal synapses erases the stored memory. The instability of long-term memory is suggested by the Salvador Dali painting, The Disintegration of the Persistence of Memory. The background shows Golgi-stained hippocampal neurons by Lorente de Nó. Credit: Science