Could do--the phenomenon was first seen in sleeping animals. Replay during REM is probably at 1X speed, non-REM (aka slow wave sleep) is in the 10-20x range. Th

Could do--the phenomenon was first seen in sleeping animals. Replay during REM is probably at 1X speed, non-REM (aka slow wave sleep) is in the 10-20x range. The dreams you remember (long, emotionally involved) tend to happen in REM. Of course, we can't ask rats what they dreamt about, but the patterns in the neural activity are very specific (we can decode the rat's position with ~5cm accuracy, and during replay we see coherent trajectories through space that look just like real movement.) Also Hassabis knows this literature well--he has published work on decoding human memories in hippocampus from fMRI data and we talked shop about replay a long time ago. (Very thoughtful and friendly person FWIW).