memory consolidation Flashcards
what did Mueller & Pulzecker 1900 do
- New memories initially fragile, but soon resistant to interference.
- Ss learnt a list of paired-associate syllables (AB) and were tested in cued recall (using the first syllable, A).
- Interpolating another list (CD) impaired memory of the first list (AB).
- Found temporal gradient, whereby the closer in time the interfering list to the target list, the stronger its amnestic effect.
types of memory consolidation
- Cellular (synaptic)
2. System-level (whole brain)
what did Mueller & Pilzecker conclude
- Memories require time to consolidate.
- Retroactive interference compromises the integrity of recently formed—but not yet consolidated— memories.
- Interference is ‘nonspecific’, i.e. the interfering material does not have to be similar to the target material (i.e., AB vs. CD).
- Mental exertion is the interfering force.
what did Wixted say about the shape of forgetting
- The clay metaphor, i.e., the idea that memories become more and more resistant to interference fits well with forgetting curves.
- The rate with which we forget is not constant; this would be exactly the property of memoryless systems
what did Ebbinghaus (1885) argue
• Ebbinghaus (1885): the forgetting function is such that we forget less and less as time goes by.
what did Jost 1897 argue
• Jost (1897): If two memories have equal strength but different ages, the older trace will decay at a slower rate.
continuous reduction in the forgetting rate is a sign of…
continuous reduction in the forgetting rate is a sign of consolidation
what is cellular consolidation
- Occurs at the neuron level (not at the whole-brain “systems” level)
- Takes place during the first hours (and perhaps days) after initial memory formation in the hippocampus
- Fits well with the idea of a trace-hardening physiological process put forward as far as Mueller and Pilzecker
- Corresponds to the discovery of long-term potentiation (Bliss & Lømo, 1973)
what is Long-term potentiation (Bliss & Lømo, 1973)
• Long-lasting enhancement of synaptic efficacy induced by a tetanus (short burst of high-frequency stimulation) to the presynaptic neuron.
what amnesia did HM hae
anterograde amnesia and temporally graded retrograde amnesia
what is anterograde amnesia
anterograde amnesia: inability to form new declarative memories (the ‘what’)
what is temporally graded retrograde amnesia
temporally graded retrograde amnesia: impairment of memories formed prior to surgery, stronger for young than old memories (Scoville & Milner, 1957) (Ribot’s law, 1881).
what is systems consolidation
• Declarative memories becoming independent from the hippocampus and more dependent on the neocortex is referred as ‘systems consolidation’.
what did Bayley et al 2006 find
Bayley et al. (2006; Manns et al. 2003): 6 amnesic patients with damage limited to the hippocampal region.
Asked Ps about news (1951-2005). Performance with controls and patients is shown right. Old memories are preserved in patients because they have had time to be cloned and presented elsewhere in the brain. The new events has worse performance in patients. However, for most memories, they are the same level as controls.
what did Smith adn Squire 2009 do
160 questions on news events over 30 years
There is a stronger hippocamus activation for newer memories. Older memories show activation in the neo-cortex
what did takashima do
Takashima et al had paired learning protocol. You have to associate a given face with a given orientation of an arrow (shown in B). this is training phase. The test phase is the following day. They need to identify the correct orientation of the face. They got a set of faces leanrt on day one and another group learnt just before the test on day two. The list learnt on day 1 is old. The list learnt before the test is new. They have manipulated age of the memories. Over the course of 24 hours, the memories engage with the hippocampus less but the neo-cortex more.
What is the significance of shift from the hippocampus (in the medial-temporal lobe) to the neocortex?
- Declarative memories stored in neocortex from the outset (e.g., sensory and semantic areas)
- Hippocampus acts as a relay station and binds them together.
- Over time, cortico-cortical associations develop, such that these memories become independent of the hippocampus.
what are complementary learning systems (Marr 1971, McClelland et al, 1995)
a) A fast learning system that holds information only temporarily (medial temporal lobe, i.e., the hippocampus)
b) A slow learning system that serves as long-term store (i.e., the neocortex)
- Information initially stored in the hippocampus is progressively fed back into the neocortex (via ??????
- Information initially stored in the hippocampus is progressively fed back into the neocortex (via ‘neural replay’),
As both systems (fast and slow) are used to encode new learning, this reactivation/redistribution has to occur ……………
As both systems are used to encode new learning, this reactivation/redistribution has to occur offline, for instance during sleep.
types of declarative memory
episodic and semantic
types of non-declarative memory
procederal skill, conditioning, non-associative, priming
what did Jenkins & Dallenbach 1924 do
Two subjects learn lists of 10 nonsense syllables until mastered
Re-tested in free recall after a varyign time interval (1,2,4 and 8hrs) filled with sleep or wake
what did Jenkins & Dallenbach 1924 find
sleep protects against forgetting
however, absence of interference is not the whole story
time of training has an influence
need less exposure in the evening than the morning for complete mastery
what did Payne 2012 find with the sleep-first effect
- Learning of related (‘circus-clown’) or unrelated pairs (‘cactus-brick’) using study-test cycles with feedback until 24 out of 40 correct.
- After 12 hrs, better performance for the sleep group, only for unrelated pairs.
- Temporal gradient a retroactive facilitation: after 24 hrs, better recall for those who slept first!
- Both absence of interference and system consolidation during SWS could be behind the effect, though logically cellular consolidation should be blind to semantic relatedness.
what is the sleep-first effect
• Temporal gradient a retroactive facilitation: after 24 hrs, better recall for those who slept first! Less forgetting than later sleeping
how do u explain sleep-first effect
• Both absence of interference and system consolidation during SWS could be behind the effect, though logically cellular consolidation should be blind to semantic relatedness.
what did Plihal and Born do
tested the differential effect of sleep composition
compared declarative and procederal memory
what did Plihal and Born find
• Double dissociation: declarative memory promoted by slow wave sleep; motor skills improved by REM-sleep
what did Plihal and Born find about declarative memory
it is promoted by slow wave sleep
what did Plihal and Born find about motor skills
motor skills are improved by REM sleep
what do we know about neural replay
(Maquet et al. 2000; Wilson & McNaughton, 1994; Rasch et al. 2007)
- Over a 24-hr period, there are privileged moments (perhaps when not much encoding is happening) during which the brain spontaneously replays to itself information recently acquired.
- Done mostly unconsciously, though some of it could reach consciousness.
- Allows other brain regions to learn the information in question.
- Slow-wave sleep (SWS) appears as a key window.
According to the model of systems consolidation put forward by Born and Wilhelm (2013), during slow-wave sleep…
According to the model of systems consolidation put forward by Born and Wilhelm (2013), during slow-wave sleep, slow oscillations occurring in neocortical regions constitutes a signal sent via the thalamus to the hippocampus to reactivate hippocampal memories.
neocortical oscillations drive ……………..
neocortical oscillations drive thalamo-corticol spindles, which themselves drive spindle-ripple events in the hippocampus: the alignment between levels is strong and controlled always by the troughs at the level immediately above.
what did Rash et al 2007 say about ‘cuing’
- Cued reactivation using an odour also present during the learning phase.
- Used spatial memory as skill.
- Re-exposure to associated odour during slow-wave sleep reactivated hippocampal areas active during learning
- Also led to enhanced memory performance the next day.
what is neural replay
During sleep or awake rest, replay refers to the re-occurrence of a sequence of cell activations that also occurred during activity, but the replay has a much faster time scale. It may be in the same order, or in reverse.
what Dumay’s reply to Schreiner and Rasch 2018
- Net performance (i.e., sums, %) hides the presence of two opposing forces at the item-level: forgetting (inability to recollect previous knowledge) and reminiscence (ability to access knowledge inaccessible until then).
- The usual decline in performance smaller after sleep than after wake does not mean that sleep just prevents forgetting.
what did Payne et al 2009 do?
Ss learns 8 lists of 12 semantically related words, all strongly associated with a missing critical target. E.g., door, glass, pane, […] for WINDOW
what did Payne et al 2009 find?
Sleeping on information returns better free recall. The duration of sleep, provides enough substrate to boost performance. Napping may not be as strong (bottom graphs).
Sleep strengthens associations between individual memory elements, and fills in the gaps!
Sleep integrates new information with long-consolidated knowledge
what did Dumay 2007 predict
They predicted, before sleep, you may have learnt ‘cathedral’ to a strong level. This declarative knowledge will not have a procedural effect on how cathedral is recognised. After sleep, cathedral could impede the recognition of other words. An indirect effect of learning
what did Dumay 2007 do
There is a difference between two conditions: exposure to cathedruke and cathedral; only exposure to cathedral. The task is given to Ps right after training. Those who slept on the new learning showed a hinderence on how they can perceive the English word ‘cathedral’. Those who were awake saw no change even if they saw ‘cathedruke’.
what did Dumay 2007 find with declarative tasks
In declarative tasks, Ps had to recall the words they were taught as a safety measure, the group that slept first is the PM group. Their declarative expression improves as they are doing the task a second time so are used to it. They also have knowledge of the words
The group that doesn’t sleep has foggiting; they have lost information. After sleep, they have improved in memory. PM group then remains awake but can increase performance by 24 hours.
If you improve a lot in declarative measure in the interval, there tend to be more interference from the novel word onto the existing words. So, declarative memories are connected as participants were good consolidators on more than one level.
what did Dumay et al 2007 conclude about declarative tasks
If you improve a lot in declarative measure in the interval, there tend to be more interference from the novel word onto the existing words. So, declarative memories are connected as participants were good consolidators on more than one level.
what did Wagner, Gais and Born do?
Examined whether sleep preferentially enhances memory for emotional narratives.
• Ss memorized the details of two small descriptions (incl. 94 content words): e.g. “manufacturing bronze sculptures” vs. “child murdering”.
• Ps were trained & woken at 22:25 or 02:15. The latter group would then sleep on the learnt material with sleep composition favouring REM sleep
• Number of content words type-recalled was the memory measure.
what did Wagner, Gais and Born find?
- REM sleep enhances, favourable, content with emotion. Sleeping does not differentiate between emotional and neutral memories in the early night. In the late night, emotional memories are boosted.
- Text retention, especially if content was emotional, benefitted more from late night sleep!
- Like the weapon effect, memories are shown as reproducing certain aspects- some are remembered more than others.
- Weapon effect could be occurring immediately. There is amplification of this affect over time oversleep
what did Payne et al do on sleep enhancing memory
- Looked at the role of sleep on memory for object and background components of scenes.
- Main components either negative or neutral, whereas background always neutral.
what did Payne et al find on sleep enhancing memory
If there is an alarming element, may be consolidating this and losing neutral elements of the scene. Without the alarm, you may consolidate the main object of attention and the background equally.
-Sleep enhanced recognition memory for emotional components to the detriment of background details.
Your memory is better after sleep than initially for the negative aspect of the scene. The neutral element starts to suffer. You can boost the memory after exposure if you sleep. But not if you stay awake.
-No such overnight trade-off for neutral scenes!
what was Dumay’s study on ‘setting the alarm’
- -This study examined whether memory consolidation gives neutral cues the power to grab attention after they co-occurred in the context of threat.
- Will surrounding emotions taint something that is originally neutral? Will the word itself become alarming?
- Participants learnt one set of associations between a made-up word and a neutral or emotional picture 7 days before the test, and another set on the day of test.
what was Dumay’s results on ‘setting the alarm’
There is no difference on the ‘same day’ with neutral and alarming
After 7 days, the alarming test grabs the attention
The consolidated set always grabs attention (even in the 0 and 6 hour differences)
o Results for emotional photos in front
Disturbance effect- cant take decision as immediately as you would. The reaction time is always longer in the emotional condition.
The decision to press the right button to slow down could be due to disturbing photos
Therefore, alarming condition was harder to learn
o Evolution of learning
Learning proceeds in a similar fashion whether in an alarming or neutral context
Emotional words are NOT harder to learn
This study shows , with consoldiation, thigns that are at first neutral, might become alarming due to the experiential context
In clinical setting, why some words are more alarming for certain individuals
Protection against forgetting occurs at …
Protection against forgetting occurs at the synaptic and systems levels.
Slow wave sleep is characterized by the hippocampus not encoding and by neural replay, which makes it ….
Slow wave sleep is characterized by the hippocampus not encoding and by neural replay, which makes it promote synaptic and systems consolidation.
Synaptic consolidation in the hippocampus may depend on …
Synaptic consolidation in the hippocampus may depend on the amount of retroactive interference, meaning that it may not be specific to sleep.
Sleep not only prevents forgetting, but it also:
Sleep not only prevents forgetting, but it also: (1) helps recover information, (2) promotes gist extraction, and (3) integrates new information with existing knowledge, amongst other things.
Consolidation (via sleep) enhances declarative memory for alarming elements to the detriment of background details. It also …
Consolidation (via sleep) enhances declarative memory for alarming elements to the detriment of background details. It also gives initial neutral cues the power to grab attention once they have co-occurred with threat.
The case of HM confirmed the link between anterograde amnesia and retrograde hypermesia
true or false?
FALSE. He did not show anything suggesting a link between encoding new memories and what was learnt before. He demonstrated an inability to learn new elements but stored his past.
In Plihal & Born (1997), the split night protocol showed that…
A. Slow wave sleep (SWS) is good for procedural knowledge
B. REM sleep has no effect on memory
C. The sequence SWS plus REM sleep promotes declarative knowledge
D. None of the above
D. None of the above
a. The sleep protocol involves training participants at either 11pm and testing in the middle of the night.
i. The first half of the night is the first aprt of the interval where there is more slow wave-sleep
b. The other training was in the middle of the night and testing at 6am
i. More REM sleep
c. This study varied the materials Ps were trained on
d. SWS improved declarative knowledge compared to being awake in that same interval
e. No effect for REM sleep
f. Mirror tracing of a star
i. No effect of sleep in early night compared to wake but in the effect of REM sleep in the second segment in the night
Recollecting memories that were previously inaccessible is called…
Recollecting memories that were previously inaccessible is called… REMINISCENCE
The fact that new emotional words do not grab attention after 6hrs of wake is in line with the notion of cellular consolidation-
true or false
FALSE
• The system of the brains structure that will ultimately demonstrate the effect we see after sleep are not about immediate learning
• If there is nothing after 6hrs of wake, there is no synaptic change. This would have shown soon after learning.
o Underlying mechanisms are not about synaptic learning but about something else such as integration effects