Tuesday, October 30, 2007

Sleep deprivation diminishes recall of neutral and positive, but not of negative, events.

We remember emotional events, particularly negative ones, better than neutral events. Sterpenich et al. show that while consolidation of neutral and posititive memories is diminished by sleep deprivation, recall of negative events is less compromised. They show that after sleep deprivation, recollection of negative, potentially dangerous, memories recruits an alternate amygdalo-cortical network, which would keep track of emotional information despite sleep deprivation. Here is their description of the work:

Declarative memories, which can be consciously and verbally retrieved, are initially critically dependent on the hippocampus. However, reliable retrieval of long-term memory depends on a process of consolidation, which partly occurs during sleep, when memories are thought to be progressively transferred to long-term cortical stores. Because people tend to remember emotional memories better than neutral ones, we wondered whether the emotional significance of a memory would enhance its consolidation in a sleep-dependent manner. During a first session, participants viewed pictures with neutral and emotional content without realizing that their memory of the pictures and their content would be tested later (called incidental encoding). Three days later, during a functional MRI scanning session, subjects indicated whether they recognized previously viewed and new pictures. Half of the subjects were totally sleep deprived during the first post-encoding night, but all subjects slept as usual during the second and third post-encoding nights. We show here that the recollection of emotional stimuli elicited larger responses in the hippocampus and various cortical areas in the well-rested group than in the sleep-deprived group, suggesting that emotional significance boosts memory consolidation of the information during sleep. Interestingly, in sleep-deprived subjects, recollection of negative items recruited another network including the amygdala, as if an alternate consolidation process allowed them to keep track of negative, potentially dangerous, information despite the cognitive aftermath of sleep deprivation.

1 comment:

jorge said...

Hi,
I get a period of a week with kind of this. Was different in the sense that I slept for several hours, but after a period (in the night) without sleep. Like get up at 12hr then sleep the next day up to 3hr. Then from 13hr to 4hr. Something like that, and was very surprising to me that this can get as result that the negative are recollected better. Today I wake at 7hr, but all the past week was very hard to manage what my feeling and some negative emotions. A very special feature when I went to sleep yesterday at 1:30hr I feel that I experience faster reactions (I saw faster, react better than normal other weeks). It was hard to explain why it happened like that but sure is not nice to have that kind of deprivation.

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