Neuroscience: Rewinding the memory record

How does the brain store sequences of experience? Clues come from brain recordings of rats running along a track. The animals' memories seem to be consolidated in an unexpected way as they rest between runs.Run that by me again...During sleep, neurons in the rat hippocampus are known to replay sequences of activity that took place when the rat was awake. A new study, in rats running around a track, eating and grooming, shows that replay also occurs repeatedly during the awake state, and that behavioural sequences are replayed in reverse order. Theories of spatial learning have previously suggested that reverse replay might be useful. Replay during the awake state might also explain in part why learning can be more effective if learning sessions are spaced out in time rather than clustered together, why hyperactivity causes learning problems, and why simply being awake and resting can help learning.

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