Memory

Question 1

Explain the Atkinson-Shiffrin model.

Answer 1

Sensory store - modality specific info, help for a few ms.
Short-term store - info held for a few secs. Can be extended via rehearsal. Limited capacity.
Long-term store - nearly limitless in duration + capacity. Includes; semantic, episodic, procedural and prospective memory.

Question 2

Explain Baddeley’s working memory model (STM).

Answer 2

All info processed by the central executive.
Visuospatial sketchpad, episodic buffer, phonological loop - fluid systems.
Visual semantics, episodic LTM, language - crystallised systems.

Question 3

What is the average visual and digit span STM capacity?

Answer 3

Visual: 4 items. Limit to storage capacity. When adding more items - capacity doesn’t increase.
Digit span: 7 ±2 items.

Question 4

Where do neurons spike during retention of spatial locations (STM)? What about during a delay phase of a delayed match-to-sample task?

Answer 4

Retention - Parietal cortex.
Spike - increased number of APs.
Delay - Prefrontal.

Question 5

What are the neural bases of visual-spatial STM?

Answer 5

Intraparietal sulcus - transient storage of visuospatial information.
Inferior-occipital areas - visual processing. Not storage.
Medial frontal brain areas - monitoring of task. Not storage.

Question 6

What are the neural bases of verbal STM?

Answer 6

Large LH activity.
Broca’s area - rehearsal.
BA 40 - storage.

Question 7

Where does chunking take place?

Answer 7

Prefrontal cortex.

Question 8

What is the role of the prefrontal cortex?

Answer 8

Chunking.
Lie (2006) - Wisconsin car sorting test, fMRI study.
Medial + dorsolateral prefrontal cortex. Increasing activity with increasing task difficulty.
Central executive in PFC.
STM + CE = working memory.
PFC involved in working memory.

Question 9

Where is STM mostly stored?

Answer 9

Posterior areas.

Question 10

What is non-declarative memory (LTM)?

Answer 10

Procedural + classical conditioning.

Question 11

What does declarative memory split into (LTM)?

Answer 11

Semantic (facts) + episodic (events).

Question 12

Where are declarative memories stored?

Answer 12

Volume of brain tissue destroyed correlated with memory performance - independent of location.
Lashley - no specific memory area. Whole brain involve in learning + memory. Study invalid.
Conclusion: memory not unitary. Different types of memory = different brain structures. Heterogenous memory. Memories are likely to be stored in brain areas involved in original sensory processing. What pathway + where pathway.

Question 13

Which case study goes against Lashley’s principle?

Answer 13

Philipp - RH removed. Normal life - no memory deficits.
Lashley’s study - used worst possible laboratory task to study memory. Maze running involves many senses. Lashley only eliminated one sense.

Question 14

Where are memories stored?

Answer 14

Inferior temporal cortex. Hippocampus.
Neurons in ITC can become tuned to a certain face! Spiking neurons correlates with memory trace.
Single neurons develops a preference to a particular object.
People with expertise in a certain area = stronger ITC response. Is this correlate of memory traces or visual perception though?

Question 15

Explain the relationship between the hippocampus and episodic memory.

Answer 15

Stronger activity of hippo and parahippocampal gyrus when recollecting material.
If remembered correctly = higher activity.

Question 16

Explain the relationship between the hippocampus and spatial memory.

Answer 16

Mouse in radial arm maze study. Episodic memory task.
With hippo lesion - unsuccessful in task.
Experience-based spatial memory relies on hippo activity.

Question 17

What are hippocampal place cells?

Answer 17

Neurons that spike when a rat is in a particular location in an environment that has been previously explored. Place cell fires when approaching the neuron’s place field.

Question 18

Explain the London taxi driver study + results (Maguire).

Answer 18

London taxi drivers - larger posterior hippocampus.
Longer the drivers were on the job = larger posterior hippocampus (and smaller anterior part). Stops the cause and effect debate.

Question 19

Briefly explain the case of Henry Molaison (Milner).

Answer 19

Anterograde amnesia - could not store new episodic memories + new semantic long-term memories.
Intact procedural + STM.
Mirror drawing task. Performance improved over time even though he said he didn’t know the task beforehand. Normal performance in non-declarative memory task.

Question 20

What is retrograde amnesia?

Answer 20

Can’t remember recent past events.

Question 21

What is anterograde amnesia?

Answer 21

Can’t store new episodic memories.

Question 22

What is transient global amnesia?

Answer 22

Very severe retrograde + anterograde amnesia. Only lasts a day!
Aetiology not completely understood - temporary lack of blood to brain?

Question 23

What is man-made amnesia?

Answer 23

Overreliance on phones + internet to store all our information..
Store info in out-sources not in-sources.

Question 24

What is Korsakoff’s syndrome?

Answer 24

Lesion in thalamus.
Anterograde + retrograde amnesia. Thiamine deficit. Lower volume of medial thalami.
Preserved procedural memory.

Question 25

What can cause Korsakoff’s syndrome?

Answer 25

Alcohol abuse, anorexia, AIDS.

Question 26

What are grandmother cells?

Answer 26

Memory entries are stored by single neurons.

Question 27

Explain the theory of distributed representation.

Answer 27

Memories stored by many neurons which form distributed networks.
Neurons which fire together, wire together. Neurons which fire out of synch, lose their link (Hebb).
Distributed networks are set up by simultaneous activation during learning. One sub-population can re-activate the whole assembly.
Inferior temporal, parietal cortex, hippo, thalamus.
Declarative LTM.

Question 28

What is some evidence for the distributed representation theory?

Answer 28

Hebbian modification.
Neurons can exclusively respond to particular stimuli and not others.
Unlikely that complex memory traces are stored by only one single cell. E.g. if we lose that cell do we lose that concept? What if concepts overlap? Complexity of memory entries can’t be coded by one single cell.
Coding is relatively sparse but memories would still be implemented in distributed networks. Whole assembly codes for that concept.

Question 29

Which area is most important in non-declarative/procedural LTM?

Answer 29

Basal ganglia.

Question 30

Which two diseases show basal ganglia deficits?

Answer 30

Parkinson’s.

Huntington.

Question 31

Explain the role of the striatum in implicit memory.

Answer 31

Weather prediction task.
PD show issues with implicit memory formation (compared to amnesiacs + controls). PD perform normally in declarative memory tasks.
Activity in striatum increases, activity in medial temporal lobe decreases.

Question 32

Where is working memory stored?

Answer 32

Parietal + PFC.