Intro to memory

Question 1

What is the engram? Who famously first failed to locate the engram? What did he find? Why did he fail?

Answer 1

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

Question 2

Inspect brain area diagrams

Answer 2

Inspect graphs

Question 3

Summarise the STM/LTM, retrograde/anterograde amnesia, episodic/semantic & declarative/non-declarative memory impairments suffered by HM

Answer 3

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

Question 4

HM shows intact LTM encoding of motor memories. Explain this in the context of mirror drawing

Answer 4

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

Question 5

HM passed the Gollin priming test. What is this?

Answer 5

A test of the ability to recognise early pictures of a progressively more clear-cut image

Question 6

HM shows spared ___ memory in terms of a normal digit span but this does not improve with ___, unlike with controls

Answer 6

Working, practice

Question 7

What causes Korsakoff’s syndrome behaviourally and biologically? What are the memory symptoms? Do patients lack insight into their condition and so confabulate?

Answer 7

Excessive alcohol intake. Thiamine (vitamin B1) deficiency, diencephalic (mamillary bodies and thalamus) and frontal lobe damage. Anterograde amnesia and sometimes also retrograde amnesia

Question 8

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?

Answer 8

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

Question 9

Which 4 categories is non-declarative memory broken down into in the conceptual taxonomy of memory?

Answer 9

Procedural memory, perceptual representation memory, classical conditioning, non-associative learning

Question 10

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?

Answer 10

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

Question 11

Explain the challenge to consolidation theory in terms of temporal gradients

Answer 11

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

Question 12

Name 2 other challenges to consolidation theory

Answer 12

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

Question 13

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

Answer 13

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?

Question 14

Name 2 other context-dependent effects of memory

Answer 14

Quiet vs. noise. Sad vs. happy mood

Question 15

Goodwin tested the state-dependent effects of alcohol on recall of words. What did he find?

Answer 15

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

Question 16

Did Goodwin replicate the effect of recalling words with recognising pictures? Why?

Answer 16

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

Question 17

How do the effects of electroconvulsive shocks on memory in rats support the consolidation model?

Answer 17

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)

Question 18

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

Answer 18

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

Question 19

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

Answer 19

Failure: ECS applied before training or before test
Success: ECS applied before training AND before test!

Question 20

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?

Answer 20

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

Question 21

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?

Answer 21

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

Question 22

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?

Answer 22

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

Question 23

How does ECS work during encoding to prevent or return retrieval?

Answer 23

By causing the re-encoding of the info into memory with an ECS association

Question 24

Squire provides evidence that ECT administered to human participants induces a…

Answer 24

Temporal gradient of retrograde amnesia

Question 25

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?

Answer 25

Because he uses recognition rather than free recall at test!

Question 26

According to MTT, why are older autobiographical memories represented by more traces?

Answer 26

Because they have been retrieved more often and each time a memory is retrieved a new trace is laid

Question 27

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?

Answer 27

MTT proponents. When the hippocampus is now COMPLETELY absent and so cannot support any traces for autobiographical memories

Question 28

What is consolidation and what are the 2 levels at which it operates?

Answer 28

The progressive stabilisation of LTMs. 1) Synaptic consolidation occurs within mins to hours, 2) System consolidation dependent on the MTL takes up to decades!

Question 29

Why is reconsolidation a risky time for memories? What are the clinical applications of reconsolidation?

Answer 29

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”

Question 30

What neural and behavioural evidence is there that consolidation occurs during sleep? It is important for behavioural studies to control for the effects of…

Answer 30

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