How the brain encodes and stores memories is one of the enduring mysteries of neuroscience. Memories are thought to be encoded by the strengthening of synaptic connections, and many researchers believe that they are retained by proteins at the synapses. And yet, while memories can persist over our entire lifetimes, these synaptic proteins are continuously being destroyed and replaced, over a time-frame of hours or days.
Several years ago, neuroscientist Roger Tsien of the University of California, San Diego, proposed that long-term memories are stored in patterns of holes created within a lattice-like structure called the perineuronal net. Sakina Palida, a graduate student in Tsien’s lab, presented evidence for such a ‘punch-card’ mechanism at the annual meeting of the Society for Neuroscience in Chicago earlier this month.