A talk I saw at SFN received a news release which was emailed to me by a reader (thanks!). I didn’t take notes during the talk, so this was a nice piece of serendipity.
The title of the talk was “Role of Sleep in Human Memory Consolidation and Reconsolidation” (Sunday, Oct 15 2006 9:15 AM – 9:35 AM) by Matthew Walker of Harvard, which was part of a symposia on “The Dynamic Nature of Memory.”
In a nutshell, the talk detailed the effects of all-nighters on the hippocampuses (hippocampi?) of college students. Dr. Walker paid 10 undergrads to stay up all night, and then to undertake a memory task the next day. The students were presented with a set of 30 words, told to remember them all, and then asked to recall the words 2 days later after being able to catch up on sleep. The hypothesis here is this: as the hippocampus is crucial in the formation and storage of new memories, presenting information at a time that the brain is sleep-deprived will negatively impact the ability to store those memories. Recall a few days later should be impaired because the info was never properly stored in the first place.
The results of the study showed that sleep-deprived students remembered 40% fewer words that students who had received a full night’s sleep, but in addition, the emotional content of the words impacted whether or not it was remembered. “Negatively-charged words” (word which would evoke feear/sadness/anger/etc) were more likely to be remembered by the sleep-deprived students that positive or neutral words. This may represent an “evolutionary safeguard against forgetting potential threats.”
Walker’s team verified that the hippocampus was involved by repeated the experiment using fMRI, which can monitor brain activity (via blood flow), with new cohort of students. This revealed that sleep-deprived students had much lower activity in the hippocampus (while viewing photographs) than student who had slept the night before.
Another good reason not to pull an all-nighter to study (you won’t remember it!) However, I would like to have seen whether the presence of stimulants, like caffiene, could mediate this effect.
FMRI study reveals that sleep-deprived students remembered 40% fewer words that students who had received a full night’s sleep, which was paired with lower activity in the hippocampus. In addition, the emotional content of the words impacted whether or not it was remembered.