6. Sleep and Memory Consolidation Flashcards
1
Q
declarative memory
A
what
2
Q
non declarative memory
A
how
3
Q
different stages of memory processing
A
- form a memory through engagement
- first representation very fragile to being overridden or competed with by new info
- need memory consolidation for it to be solidified
- you can then recall it in the future, integrating it with existing information
4
Q
dual process model
A
Ackerman & Rasch (2014) - (level 1)
- focus on specific components of sleep independently (e.g. non-REM, REM)
- explains how different sleep stages help with different types of memory consolidation
- night half paradigm used to test (early sleep SWS, later sleep REM)
- P’s tested after an episode of SWS or REM sleep, but not both
- declarative memories = SWS
- non-declarative = REM
- a further extension of the model predicts that simple motor tasks are associated with stage 2 sleep
5
Q
dual process model limitations
A
- ignores contributions of stage 2 sleep to memory
- stage 2 sleep was comparable across participants but it may have differed in some aspects (e.g. spindle density)
- declarative/non-declarative have been covered by the model but what about other kinds of memory?
6
Q
two step model
A
- level 2
- interested in the REM/non-REM cycle attempting to explain the importance of the cycles
- early hypothesis
- non adaptive memories are weakened during SWS
- adaptive (help retain survival) memories are integrated within REM sleep
- this shows a removal of memories that are not important encoding the important ones left
- later hypothesis
- the last 2 decades of research suggest a role of SWS in memory consolidation
- SWS memories to be retained are distinguished from irrelevant traces that undergo downgrading or elimination
- processed memories are stored again during REM which integrate them with pre existing memories
7
Q
two step model evaluation
A
+ animal and human evidence
+ sleep stages not viewed in isolation
+ cyclic structure of sleep is important to recognise
- difficult to test directly
- what are exact functions of each sleep stage
8
Q
active system consolidation model
A
- level 3 - dominant model now
- integrated aspects of previous two levels, using specific stages and cyclic structure
- consolidation vital for memories (strengthening or stabilising) and this can’t be achieved through wakefulness
- Born et al (2006, 2011, 2012)
- when memories are first encoded they are done so into the hippocampus and neo-cortex (highly distributed)
9
Q
born et al (2006, 2011, 2012)
A
- a new memory = the distorted memory nodules are brought together by the hippocampus via hippocampal neocortical connections to create a coherent representation of that memory in consciousness
- slow oscillations = thought to drive a reactivation of memory in the hippocampus and neocortex
- this weakens the hippocampal neocortical connections but strengthening the cross cortical connections
- memory is no longer dependant on the hippocampus but completely depends on the neocortex, retrieving independently of the hippocampus
- memory is now thought to be integrated within your LTM
- SWS key for replaying memories
- REM = important for integrating these memories and strengthening synaptic connections
10
Q
targeted memory reactivation (TMR)
A
- an expansion of the active system consolidation model
- key aspect of ASC model is that memories are replayed in your sleep (reactivation)
- you can manipulate what people reactivate when people sleep (by triggering it with smells and sounds)
- during the encoding period, if you are subject to some kind of smell/sound, you can cue this reactivation when people are asleep by producing the same smell/sound
- sounds in SWS may also trigger hippocampal replay showing artificial enhancement of a normal process
- this benefits declarative but not procedural memory
- Rasch et al (2007)
- Rudoy et al (2009)
11
Q
Rasch et al, (2007) - method
A
- targetted reactivations
- participants learnt the location of specific cards
- they were then tested on the location of where the specific card was
- whilst learning and being tested the P’s were subject to an odour (rose)
- whilst during SWS, P’s were presented with the odour or the specific picture (control)
- when memory reactivations were cued during SWS, those who were subject to the rose were signficiantly better at remembering the location of the card
12
Q
Rasch et al, (2007) - results
A
- re-introducing the odour acted as a contextual cue for memory representations associated with the odour, which were then reactivated and consolidated
- Rasch carried out lots of control procedures (odour during SWS on its own, learning and REM, learning and waking)
- odour has to be present during learning and SWS to have beneficial effects
- they repeated the study whilst recording fMRI = hippocampus lit up when the smell was delivered during SWS
- this study shows behavioural and physiological evidence for the importance of memory reactivations during SWS in memory consolidation
13
Q
Rudoy et al (2009) - method
A
- investigated whether you can target specific memories and reactivate specific memory representations using sound
- P’s shown 50 objects accompanied with a corresponding sound
- learning phase = learnt location of these objects
- P’s took nap where SWS occurred and 25 sounds were played
- P’s were then tested assessing difference in recall of location between played and unplayed sounds during SWS
14
Q
Rudoy et al (2009) - results
A
- memory decline was signficantly reduced when accompanying sounds were played during SWS
- less error when cued by sound
- can target memories specifically in SWS using odour and sound
15
Q
sleep, memory and age
A
- SWS decreases with age (Carskadon & Rechtschaffen, 2005) alongside memory ability
- Neurbauer (1999) - hypnogram demonstrating typical sleep characteristics comparing young to elderly
