function and emotions in sleep Flashcards
active systems consolidation
a system for consolidating new memories/moving memories into long term storage during sleep
the hippocampus creates temporary binding connections between different memory traces in the neocortex - over time, as the hippocampus replays memory traces during sleep, they become independent of the hippocampus
what are the main EEG characteristics thought to play a major role in the hippocampal neocortical dialogue
- slow waves (neocortex)
- sharp waves/ripples (hippocampus)
- spindles
why do we call it ‘active’ systems consolidation
because every time we replay a memory it changes
active systems consolidation is a process through which memories are:
- replayed
- potentiated
- transformed
which neural oscillations predict learning in which stages of sleep?
n2 and 3 (sws) : spindles predict learning
rem: theta, alpha, high beta predict learning - delta predicts learning in all stages
what affects the consolidation of memories during sleep?
sleep doesn’t consolidate all information uniformly:
consolidation is influenced by:
- context
- goals
- motivations
- salience
- emotional stuff - more emotional, more likely to remember
how does sleep extract the gist of new experiences?
one role of sleep isn’t the strengthening of individual memory items, but their abstracted assimilation into a schema of generalized knowledge - reorganizes what we’ve learnt
- selective consolidation - things learned during the day are tagged as either relevant or irrelevant (irrelevant stuff is weeded out)
- item integration - newly learned things are integrated into general knowledge
- multi item integration - we can use the pool of general knowledge to extract the gist of a memory, extrapolate rules about the general group, and construct false memories
hippocampal neocortical dialogue in memory
idea that information initially requires binding by the hippocampus. Over time, during sleep, the hippocampus reactivates the networks that correspond to that information/memory and gradually strengthens the connections between neocortical sites involved in the memory, eventually allowing the original information to be activated independent of the hippocampus. Blocking sleep, doesn’t allow this transfer, decreasing the capacity for new hippocampal learning the next day
synaptic homeostasis hypothesis
encoding during wakefulness induces a global upscaling of glutamatergic synapses in cortical and subcortical structures (including hippocampus) - in sleep, average connectivity in these networks is downscaled to baseline levels to prevent and accumulation of upscaling that would lead to excessive energy and space demands (important things can also be upscaled)
- this leaves room to learn new things the next day!
why is sleep an affective blanket
we remember the stuff that was more emotional but rem sleep consolidates and integrates emotional memory while decoupling it from the emotion that initially ‘tagged’ it for memory, thus reducing anxiety when reactivated
means that less amygdala and adrenergic activity when memory is reactivated after sleeop
ptsd
able to remember things exactly as they happened, and nightmares that replay episodes (this stuff never happens normally)
….most of what we know on emotional disassociation of memory is from ptsd - take the pathological example and reverse engineer what should actually happen
memories never got decoupled from emotion and amygdala still has a strong effect
what happens to our emotions when we are sleep deprived
we have a stronger emotional response to everything since the amygdala is more involved in memory consolidation
this happens because when we don’t get enough sleep, the prefrontal cortex has a weaker connection to the amygdala and is less effective at dampening its response
vicious cycle of sleep and anxiety
Anxious = harder time falling asleep= sleeping poorly = more amygdala= more anxious = less sleep
Lessen anxiety = improve sleep, improve sleep = lessen anxiety
….could be seen as multiple sites of intervention? Or just a circle of doom…
activation of the amygdala following sleep deprivation
- Threat perception is enhanced
- Neutral stuff is perceived as threatening
So…we are still able to perceive threats, but brain activity is magnified…so we are more sensitive over all
- Neutral stuff is perceived as threatening
memory replay in rem sleep
Possible that there is a replay of different memories in rem and nrem - rem associated with procedural, implicit learning
- Found that after procedural task, same regions were activated in rem
- Predict post sleep task improvement
targeted memory reactivation in sleep (tmr)
Idea: triggering memory replays during sleep
Tmr: replay of sensory cues during sleep that were previously associated with learning
Rat studies 🐀: 1985: hars et al, electric shocks in wake followed by same shocks in rem sleep = better performance
Human studies:
1989 (geurrien et al): auditory stimulation in phasic rem sleep - improvement on a morse code learning task
1990 (smith et al): clock sound during phasic rem sleep - improvement on a complex logic task
odors and memory consolidation in sleep
- Odor paired with learning procedure, then re-exposure during sleep
- Does sleep increase learning preferentially when paired with cued odor
- Odor + sws = improves declarative memory —-hippocampus
- Odor + rem does not
Odo + procedural memory - no improvement
TMR could be used to enhance…..
· Declarative memory
· Language
· Procedural memory
· Emotional memory
· Spatial memory
· Social bias
Sleep therapies
