How the Brain Learns During Sleep

Although we know that we need sleep in order to learn, the mechanism is uncertain (see Journal Watch Psychiatry Feb 12 2007 and Mar 19 2007). One theory is that memories are reactivated and consolidated during sleep, but it has been difficult to demonstrate this process. These investigators used odor cues presented during learning and again during subsequent sleep as triggers for memory reactivation.

There were two tasks, performance of which improves after sleep: a hippocampal-dependent, declarative-memory task (learning the location of card pairs, similar to the game Concentration) and a procedural-memory task (finger-tapping sequences). The 18 volunteers learned the tasks at night while the smell of a rose was presented. Later that night,…