Intro to memory Flashcards
What is the engram? Who famously first failed to locate the engram? What did he find? Why did he fail?
The physical representation of memory in the brain. Lashley (1927). That the greater the amount of cortex lesioned, the greater the memory deficit & that no particular brain area was the memory area. Because he never lesioned the hippocampus & the task (rat remembering a maze route) also required action & motivation
Inspect brain area diagrams
Inspect graphs
Summarise the STM/LTM, retrograde/anterograde amnesia, episodic/semantic & declarative/non-declarative memory impairments suffered by HM
STM: spared, LTM: eliminated, declarative: impaired, non-declarative: intact, episodic: retrograde temporal gradient (controversial), semantic: anterograde but not retrograde amnesia, episodic: anterograde amnesia and retrograde temporal gradient
HM shows intact LTM encoding of motor memories. Explain this in the context of mirror drawing
HM becomes better with practice at drawing within the boundaries of the shape’s contours e.g. is better on the 3rd day than the 1st day of mirror drawing
HM passed the Gollin priming test. What is this?
A test of the ability to recognise early pictures of a progressively more clear-cut image
HM shows spared ___ memory in terms of a normal digit span but this does not improve with ___, unlike with controls
Working, practice
What causes Korsakoff’s syndrome behaviourally and biologically? What are the memory symptoms? Do patients lack insight into their condition and so confabulate?
Excessive alcohol intake. Thiamine (vitamin B1) deficiency, diencephalic (mamillary bodies and thalamus) and frontal lobe damage. Anterograde amnesia and sometimes also retrograde amnesia
What are amyloid plaques and neurofibrillary tangles? Where are they first seen? Where in the MTL is first damaged? Which is lost first: recent or remote memory? What is their typical life span once diagnosed?
Clumps of protein fragments which accumulate outside neurons vs. twisted strands of another protein which form inside neurons. In the transrhinal region. The hippocampus. Recent memory. 3 to 20 with an average of 8 years
Which 4 categories is non-declarative memory broken down into in the conceptual taxonomy of memory?
Procedural memory, perceptual representation memory, classical conditioning, non-associative learning
Describe the process of perception to LTM according to the standard model of consolidation (Squire, 1992) which explains HM supposed temporal gradient. Is the hippocampus in the cerebral cortex, neocortex or subcortex?
Info is initially registered in widespread, neocortical area, then bound by the hippocampus in seconds to minutes. Info is gradually consolidated so that it’s storage and retrieval is no longer dependent on the hippocampus. Cerebral cortex
Explain the challenge to consolidation theory in terms of temporal gradients
1) we cannot verify how steep the gradient of retrograde amnesia is: older memories may be more easily recalled because a) more memorable events occurred in childhood, b) the childhood memories recalled are more semantic or c) childhood is more susceptible to confabulation
Name 2 other challenges to consolidation theory
1) Why does the consolidation mechanism show such variability in the time taken to consolidate (seconds in rats to decades in patients)? 2) Are memories lost in amnesia because they weren’t transferred to neocortex in time or because they’re more difficult to find? I.e. a problem of retrieval rather than storage location
What is context- or more generally state-dependent memory, as demonstrated in Baddeley’s famous diving experiment? Name a new Q raised by Baddeley’s study
The finding that recall is enhanced when it occurs in the same context or brain state as encoding. What about the context facilitates recall e.g. water pressure or perception of water?
Name 2 other context-dependent effects of memory
Quiet vs. noise. Sad vs. happy mood
Goodwin tested the state-dependent effects of alcohol on recall of words. What did he find?
That recall after the consumption of alcohol was better if the info had also been encoded under the influence of alcohol, whereas sober recall was better after sober encoding. Recall was worse when the retrieval state did not match the encoding state. I.e. S(sober)A and AS
Did Goodwin replicate the effect of recalling words with recognising pictures? Why?
No because being in the same state enhances recall by providing a cue. Whereas in recognition tasks cues don’t help because free retrieval is not necessary
How do the effects of electroconvulsive shocks on memory in rats support the consolidation model?
Because ECS applied every time after the rat finds the food removes the memory (Hayes, 1948). But if the interval between learning and ECS is increased, ECS is less likely to impair learning because the memory has a longer opportunity to be consolidated into neocortex (McGaugh, 1966)
Name 4 factors which moderate the steepness of the memory loss gradient, 3 of which are not compatible with consolidation theory. I.e. 4 factors which make the ECS disruption more or less likely after increasing the time between learning and the shock
1) ECS intensity
2) Degree of familiarity with the test apparatus
3) Degree of familiarity with ECS
4) Exposure to training cues between learning and ECS
Thompson & Neely (1970) reviewed by Rawlins (1986) found that ECS application causes state-dependent effects on memory. Give 2 basic examples of retention failure and 1 basic example of retention success
Failure: ECS applied before training or before test
Success: ECS applied before training AND before test!
What do Thomspon’s findings suggest about the brain state experienced 25 mins after ECS I.e. when training occurs? What findings re: the effect of changing ECS timing prior to retrieval demonstrate this?
That a specific “25mins-post-ECS brain state” is associated with the info learnt at training and later acts as a retrieval cue. Retention is more likely to be impaired, the greater the difference between the ECS-training interval and the ECS-test interval e.g. if one is 25mins and the other is 40mins
What is so revealing about Thompson’s finding re: the question of do we have ever forget info? Does ECS erase memories? Does it according to consolidation theory?
They suggest info is never lost but just difficult to find. If we are returned to the encoding brain state, then the memory will return. ECS therefore does NOT work by erasing memories. Yes
How did Thompson demonstrate the state-dependent effects of ECS on instrumental learning in rats? How do the findings differ from what consolidation theory would predict?
ECS applied after learning task C prevented retrieval of task C & A memories because both tasks had in common the fact that they were motivated by foot shock avoidance. Task B memory retrieval was intact because it was motivated by food reward instead. CT would predict a greater likelihood of A than B than C retrieval
How does ECS work during encoding to prevent or return retrieval?
By causing the re-encoding of the info into memory with an ECS association
Squire provides evidence that ECT administered to human participants induces a…
Temporal gradient of retrograde amnesia
Squire (1976) refutes Thompson’s ECS evidence directly by investigating the effects of ECT in inducing anterograde amnesia in human participants. Why does he not find a X mins prior to learning/test effect of triggering the memory?
Because he uses recognition rather than free recall at test!
According to MTT, why are older autobiographical memories represented by more traces?
Because they have been retrieved more often and each time a memory is retrieved a new trace is laid
Who argues that temporal gradients in retrograde amnesia may sometimes be flat or absent: SMC or MTT proponents? When is this the case do they argue?
MTT proponents. When the hippocampus is now COMPLETELY absent and so cannot support any traces for autobiographical memories
What is consolidation and what are the 2 levels at which it operates?
The progressive stabilisation of LTMs. 1) Synaptic consolidation occurs within mins to hours, 2) System consolidation dependent on the MTL takes up to decades!
Why is reconsolidation a risky time for memories? What are the clinical applications of reconsolidation?
Because the memory is deactivated and so may be reinforced but also is vulnerable to being lost. PTSD could be treated by re-activating and overwriting the memory, though total suppression is unlikely given the availability of cues = the Lady Macbeth argument: “what’s done cannot be undone”
What neural and behavioural evidence is there that consolidation occurs during sleep? It is important for behavioural studies to control for the effects of…
1) The hippocampus was more active during slow wave sleep in Pps who had learnt a spatial navigation task vs. those who hadn’t
2) Pps became better at the spatial navigation task after sleep compared to pre-sleep (Peigneux, 2004). Time
