W8.2 and 9.2 (N): Neural replay, sleep and memory consolidation Flashcards
(12 cards)
How did Jenkins and Dallenbach (1924) investigate syllable learning in sleep and wake?
Two ppts learnt lists of 10 nonsense syllables until mastery
Re-tested in a free recall after a varying time interval (1,2,4 or 8 hours) filled with sleep or wake
If there was sleep between memory and testing, performance was better
Sleeping protects against forgetting
Less stimulation when you sleep- reduces interference of learning- this is the passive view
Promoting memory consolidation and transfer across regions
What is the deepest sleep stage?
Non rem stage 4
What forms of memory are declarative?
Episodic and semantic
What forms of memory are non declarative?
Procedural
Conditioning
Non associative
Priming
How did Born (1997) investigate the differential effect of sleep on different memories and what did they find?
Tested the differential effect of sleep composition, comparing declarative and procedural memory
Paired associative learning and mirror tracing
Declarative task for paired associate cued recall- difference depending on if the experiment occurred during first half of the night or the latter half
Second half- woken up or 2 or 3am, learn the content and then woken up
Declarative task did not show any difference for being asleep or awake when done in second half of night (rem sleep). Difference only occurred when it was done in the first half of the night- showed the sleep group for the first half of the night performed the better- more non REM
For the procedural task (mirror tracking) the opposite was found- the late sleep group performed much better - more REM
Double interaction for first half of night implicates factors for different patterns in the second half of the night
REM- procedural promoted by sleep in latter half
How did Payne et al measure memory for semantically related and unrelated declarative info in sleep?
Learning of related or unrelated pairs of words using study test cycles with feedback until 24 out of 40 correct. Training at 9am with immediate retest or at 9am and then 9pm. Another group did evening training and goes to sleep straight away. Mix of delay and no delay.
Performance improves between training phase and test phase but only in the sleep group- wake group has performance decreased by the delay
After a 24 hour retest- low performance
First sleep effect- temporal gradient a retroactive facilitation
Both the absence of interference and system consolidation during SWS could be behind the effect
What is neural replay and how does it relate to sleep?
Over a 24 hour period, there are privileged moments during which the brain spontaneously replays to itself information recently acquired- this is done mostly unconsciously though some of it could reach consciousness
It allows other brain regions to learn the info in question
Slow wave sleep (SWS) appears to be a key window- regeneration, idea that the hippocampus stops being plastic in this time (cannot learn new things)
How do slow wave sleep and neural replay interact (three layers)?
Brain activity seen in neocortex are slow waves and so slow activity- this triggers activity in the middle layer, the thalamus
When the face goes up in a slow oscillation, it goes up in a spindle
Ripple events
Alignment across these layers
How did Rash et al investigate neural replay when using perfume?
Memory game- grid of cards with pairs of objects where ppts had to remember- this is the behavioural/memory task
Learning locations of each pair- in some conditions, a perfume was sprayed in the room which ppts was not aware of
Given cue (odour) memory will contain various contextual info
As soon as they enter slow wave sleep- same perfume was injected into the air- if ppts are neural replaying the info, this will guide what is being replayed- this increased memory the next day due to priming- reactivated hippocampal areas active during learning
Only occurred during sleo wave sleep and not any other stage or wakefulness
How does sleep make previously inaccessible memories accessible? (Dumay, 2018)
Separation of maintained and gained items
Sleep was found to increase the probability of gaining access to previously inaccessible knowledge in both recall and recognition and to prevent forgetting beyond wakefulness in only recall
Shows sleep does not just stabilize memories, it makes them more accesible
How does sleep promote pattern or ‘gist’ extraction?
Payne et al (2009) relied on a paradigm to examine the influence of sleep on memory formation and distortion- Ss learnt 8 lists of 12 semantically related words that were all strongly associated with a missing critical target e.g. door, glass, pane- ppts not aware there was a missing word in the list connected to all items in the list
Overall recall performance after the interval- 12 hours if the overnight sleep protocol; showed people were better able to recall items off the list if they had slept compared to if they had not
Sleep pushes the central word- same effect was seen for napping as far as the target words
Critical word that is missing is believed to be included in the list- the idea is that the gist of the list is extracted as you sleep, and makes you believe that the related word (window) was there
Sleep strengthens associations between individual memory elements in the list and FILLS the gap. Network of interconnected memories boosts the missing word
How does sleep integrate new information with long-consolidated knowledge? (Dumay)
Made new word ‘cathedruke’ for example for ppts to learn, training phase for an hour where they learnt similar words
Some ppts were exposed to the words in the morning and had 12 hours of wakefulness, whereas those tested in the evening had 12 hours of sleeping
Task was to listen to the English words and tell whether the sound is faulty in these speech trials- similar to an emotional stroop task
predicted that if neural replay is useful, initially, after learning for many exposures, the novel word cathedral would not be in contact with words you already know (old knowledge)
so prediction is that native language should not be affected by this training- it is only once you have slept that this knowledge would have been trained and connected to the old knowledge
They found that after being exposed to a new word, there was no effect to how you heard the old word, whether you had slept or not. However, without further exposure, items of the word ‘cathedral’ started to show interference, but only for those who had slept in the interval between training and the test point
Conclusion of the study is that sleep helps to assimilate new knowledge with existing knowledge- new words embedded in native language only when you sleep.
