Play it again: reactivation of waking experience and memory.
In the May issue of Trends in Neurosciences, on pages 220-229, authors O'Neill et al. highlight emerging evidence suggesting that sharp wave/ripple events in the hippocampus coordinate the reactivation of memory traces. The cover image depicts a representationof reactivation during sleep. The background image shows a closed eye with traces of sleep-associated local fieldpotentials, to represent sleep. The place fields of four cells are illustrated, of which the blue and red cells show overlappingfields.
This month Colin McNamara and colleagues report compelling evidence of how rewarding or novel experiences strengthen newly-encoded spatial memories. The hippocampus provides the brain with representations of space (J. O'Keefe and J. Dostrovsky, 1971) but newly-formed hippocampal representations may degrade with time unless stabilized by additional processes.