Internally Organized Activity During Offline Brain States

Abstract

A prime example of internally organized patterns is observed during sleep. The best studied of these is the sharp wave ripple in the hippocampus. Neuronal sequences during ripple events reach back to the past to replay snippets of waking experience at times when the brain is disengaged from the outside world. This process may consolidate episodic memories and stitch together discontiguous experiences, thereby giving rise to creative thoughts. In addition, neuronal assembly sequences during ripples also act as internalized, vicarious, trial-and-error mechanisms that can assist with subconscious optimization of future plans. Because the same neuronal substrate can perform both retrospective and prospective operations, it is not clear whether the traditional separation of postdiction (i.e., memory) from prediction (i.e., planning) is justified.