Fig. 4.
Differences in brain activity during the 6-month retest session for correctly recalled words learned before sleep vs. before sleep deprivation (S-SD). (A) Correct word recall after 6 months activates the mPFC and the occipital cortex more strongly for words from the sleep condition than for words from the sleep-deprivation condition. Note that at the 2-day interval, no activity per se was found, but only a strong functional relation to hippocampal activity. Now, at the 6-month interval, independent mPFC activity is found, but no more significant hippocampal activity. (B) The difference in brain activity in the mPFC developed mainly during the interval between the 2-day and 6-month recall sessions. It is supported by a steady increase in mPFC activity for words from the S condition over the 6-month period (open circles) and a marked drop in mPFC activity for words from the SD condition (filled circles) during the 6-month session ([−6 26 −10], Z = −3.87, PSVC = 0.004).