Replay of neural patterns during sleep

Learning-related patterns of neural activity replay in the brain during sleep, and it has been suggested that this replay may be important for the consolidation of memory. A paper in this week's Nature Neuroscience reports the first observation of replay activity in the medial prefrontal cortex (mPFC), finding that it coincides with similar patterns in the hippocampus, an area known to contribute to memory formation and retrieval.

Sidney Wiener and colleagues recorded activity from groups of mPFC neurons in rats while they learned which way to turn in a maze and while the animals slept post-learning. As the animals learned their way around the maze, the activity of the mPFC neurons changed. Similar patterns of activity were replayed afterwards while they rats slept. These replay events usually occurred at the same time as stereotyped activity in the hippocampus.

The medial prefrontal cortex is thought to play a critical role in decision-making, and has previously been implicated in memory. These results however are the first to look at its activity during sleep, supporting the idea that neural activity during sleep may play a role in memory consolidation.