Persistence of neuronal representations through time and damage in the hippocampus

Robust memories through neuron networks How does the brain store information over a long period of time? Gonzalezet al. chronically implanted custom-built high-sensitivity microendoscopes and performed long-term imaging of neuronal activity in freely moving mutant mice. The majority of neurons were active on most days, but their firing rate changed across sessions and tasks. Although the responses of individual neurons changed, the responses of groups of neurons with synchronous activity were very stable across days and weeks. In addition, the network activity in hippocampal area CA1 recovered after an extended period without performing the task or even after abnormal activity induced by local lesions. These findings indicate the presence of attractor-like ensemble dynamics as a mechanism by which the representations of an environment are encoded in the brain.Science , this issue p.821