Natural sleep, but not propofol-induced anesthesia preserves spatial and procedural memory consolidation

Propofol-induced general anesthesia and natural sleep are both associated with GABA-A-ergic inhibition and slow-wave activity. Whereas sleep actively supports memory consolidation, consolidation may be disrupted during anesthesia. Here, we compared EEG and memory data from 19 participants undergoing surgery under propofol-induced anesthesia with data from 17 participants taking a nap. In both groups, participants completed a hippocampus-dependent spatial memory task (Virtual Water Maze) and a procedural memory task (Mirror Tracing) before (pre) and after (post) an interval filled with either anesthesia or sleep. Performance declined from pre to post in the propofol group for both tasks, whereas it remained stable in the sleep group. Slow oscillations (SO) occurred during both non-REM sleep and propofol-induced anesthesia. However, only during non-REM sleep did SOs show increased spindle activity during the SO upstate. Together, these findings suggest that propofol anesthesia disrupts memory consolidation, most likely because SOs under anesthesia lack the spindle coupling that mediates the hippocampal-neocortical information transfer underlying systems memory consolidation.