Human memory

Question 1

What are the two most basic types of memory? what are these based on?

Answer 1

Short-term and long-term

- based on the length of the period of time the information is retained for

Question 2

Describe short-term memory

Answer 2

• information decays very rapidly (unless rehersed) - scale is seconds
• has limited capacity

Question 3

What can short-term memory be shown by?

Answer 3

Tests such as:

• Digit span test → measure verbal short-term memory (normally about 7 items can be retained)
• Cori block test → measures visuospatial short-term memory. by requiring the subject to remember locations tapped in correct sequence (normally about 7 items retained as well)

Question 4

What is memory?

Answer 4

the creation of an internal representation of a percept/idea based on past experience which then later affects experience and behaviour

Question 5

Shiffrin and Atkinson model

Answer 5

1968

environmental input → sensory memory → short-term memory → long-term memory (through rehearsal)

Question 6

What are double dissociations?

Answer 6

When two related mental processes are shown to function independently of each other → brain structures that control a function work independently

Question 7

Discuss double-dissociations within memory

Answer 7

Patients studies reveal double dissociation between verbal and visuospatial memory (different anatomical locations):
• Patient KF (Shallice and Warrington, 1970) with a left parietal lesion had a digit span of 2 (impaired STM), but normal visuospatial and long-term memory;
• By contrast, patient ELD (Hanley et al, 1991) with a right hemisphere lesion had an impaired visuospatial span, but normal digit span and long-term memory.
• This evidence from patients with lesions is supported by PET studies in healthy humans.
Therefore, it is though that verbal short-term memory is localized to the left parietal lobe, while visuospatial short-term memory is localized to the right parietal lobe. It is now thought that early sensory areas in the cortex may also play a role in short-term memory storage.

Question 8

Discuss how these different types of memory change with age

Answer 8

Short-term memory improves with development (Gathercole et al, 2004) and declines with age (Reuter-Lorenz and Park, 2009). But with age, semantic (type of LTM) knowledge remains intact.

Question 9

Peterson & Peterson

Answer 9

1960
Asked individuals to remember a series of number and repeat it back
They observed a curve in decay
Illustrates STM decay

Question 10

What is working memory?

Answer 10

Working memory refers not just to storage, but to manipulation of short-term memory contents.

Question 11

What is working memory thought to consist of?

Answer 11

• Executive control (PFC) = mechanisms that manipulate contents of short-term memory, for example to allow performance of a reverse digit span test where people are asked to recall a sequence of numbers in reverse;
• Storage systems (parietal lobes + early sensory areas?), which can be further subdivided into the
• Visuospatial sketchpad;
• Episodic buffer;
• Phonological loop.

Question 12

Draw a diagram of working memory. Who came up with this?

Answer 12

See Eva’s notes

Fig 2. The Working Memory Model Components (Baddeley and Hitch, 1974)

Question 13

What is the visuospatial sketchpad?

Answer 13

A component of the working memory model which stores and processes information in the visual or spatial form

Question 14

What is the phonological loop?

Answer 14

Component of the working memory model that deals with spoken or written material

Question 15

What is the episodic buffer?

Answer 15

A ‘backup’ store which communicates with both LTM and the components of the working memory

Question 16

In the Baddeley model, what does ‘working memory’ replace?

Answer 16

STM

Question 17

What does the phonological loop consist of?

Answer 17

Two parts:

• short term phonological store containing autotory memory traces subject to rapid decay
• articulatory rehearsal component that can revive the memory traces

Question 18

What is an area of the brain that is crucial for working memory?

Answer 18

Frontoparietal netwroks (note similarity to attention networks)

Question 19

Discuss views about how fronto-parietal networks contribute to working memory?

Answer 19

Parietal cortex - maintenance/ storage
Prefrontal cortex - manipulation and monitoring info in STM
BUT now clear that even early sensory areas play some roles in STM storage

Question 20

Gathercole et al

Answer 20

2004
demonstrated that short term memory capacity improves with age up to a point (20) after which we know there is a decline in short term memory (along with long term memory and other cognitive functions such as processing speed)

Essentially tested individuals in a variety of recall tasks, ranging from simple verbal storage to complex working memory functions and visuo-spatial memory functions, and found that in each test the score trend was correlated with increased age
Whilst STM and LTM decline after this point (20-80), sementic knowledge remains the same
With maturation of frontoparietal networks???

Question 21

Jaeggi et al

CLINICAL IMPLICATIONS OF THIS STUDY?

Answer 21

2008
Short-term memory capacity and working memory are highly related to intelligence. However, whether training short-term memory can improve intelligence is highly controversial. A 2008 paper by Jaeggi et al showed that training on a working memory task may improve fluid intelligence - the ability to reason and to solve new problems independently of previously acquired knowledge. They trained the working memory of participants with a very demanding tasks where they saw to series of synchronously presented stimuli - single letters and spatial locations marked on a screen. The task was to decide for each string whether the current stimulus matched the one that was presented n items back in the series, with n changing to adaptively to maintain the task’s demands. During the study, all participants improved greatly on the task, with the improvement correlating positively with the length of training of participants in sub-groups. All participants also improved on the fluid intelligence tests, but the improvement in trained subjects was significantly greater than in controls who didn’t receive training, and also showed dose-dependency: more training was associated with greater improvement
Clinical implications → we can train working memory to ward off degenerative dementia

Question 22

What can LTM be divided into?

Answer 22

subdivided into explicit or declarative, which involves conscious recall, and implicit or non-declarative, which doesn’t require it.

Question 23

What is LTM?

Answer 23

any memory that persists for longer than a few tens of seconds

Question 24

Discuss anatomicial segregation of STM and LTM

Answer 24

Long-term memory and short-term memory are clearly anatomically segregated. We’ve already seen examples of lesions that affect short-term, but not long-term memory. Likewise, there are lesions that affect long-term, but not short-term memory, a prime example being bilateral hippocampal resection performed in patient H.M. in 1953, which very severely affected his long-term memory.

Question 25

Discuss Ribot’s law and how it has been illustrated by individual cases

Answer 25

Ribot’s law states that old memories are more resistant to disruption or loss than new ones, and this was illustrated in H.M. who had complete anterograde amnesia, but graded retrograde amnesia with intact memory of distant events. This was also illustrated by P.Z. (fictious initials), who was an eminent professor and wrote his autobiography shortly before the onset of Korsakoff’s syndrome, an amnestic syndrome associated with chronic thiamine deficiency resulting in thalamic and mammillary body damage, often in long-term abusers of alcohol (Butters and Cermak, 1986)

Question 26

Anatomical representation of memory consolidation.. How does patient HM represent this?

Answer 26

It is initially hippocampal-cortical - but eventually transfers to the cortex

So lesions of hippocampus won’t erase old memories which are consolidated and robustly represented in the cortex. Hence graded retrograde amnesia in HM •	But hippocampal lesions would prevent consolidation of new memories. Hence severe anterograde amnesia in HM

Question 27

What is explicit memory further subdivided into?

Answer 27

Semantic (facts and general knowledge) and episodic (personally experienced events)

Question 28

In patients with hippocampal damage, is episodic or semantic particularly effected?

Answer 28

Episodic

Question 29

Describe the memory consolidation theory

Answer 29

The graded nature of retrograde amnesia is thought to be explained by memory consolidation theory. It suggests that episodic memories are ultimately stored in the cortex (in the corresponding sensory areas), but their recall initially depends on cortico-hippocampal connections bringing different modalities of one episode together. Gradually, connections between cortical areas storing the modalities corresponding to one episode appear, and hippocampal involvement is no longer a necessity.

Question 30

What is seen in AD with regard to episodic memory?

Answer 30

In AD, episodic memory impairment and medial temporal lobe atrophy are seen.

Question 31

What is the one memory domain that does not decline with age?

Answer 31

Semantic

Question 32

What has been linked to semantic dementia? By who?

Answer 32

. It has been linked to atrophy of left temporal pole (Mesulam et al, 2009).

Question 33

Describe Hodges

Answer 33

2008 - demonstrated progressive loss of semantic knowledge in semantic dementia

semantic dementia patients can repeat the word “ostrich” but have difficulty pointing to it when shown pictures of birds. They lack the conceptual knowledge of what an ostrich is.

Question 34

What do the primary and recency effects describe?

Answer 34

describe the fact that we remember best the beginning and the end of the list.

Question 35

How can we interfere with the recency effect? What does this mean about the primacy effect?

Answer 35

30 seconds of counting backwards by 3s leads to loss of the recency effect. This is called a ‘filled delay’ because the delay period is filled with an activity. Counting backwards prevents rehearsal and retention of words in STM. Thus recency effect is thought to be mediated by STM. In line with this, it is conserved in people with amnesia. However, the primacy effect is lost in them, and it is therefore thought that that is mediated by long-term memory.

Question 36

Discuss implicit memory in patient HM. What did he show us about it?

Answer 36

Again, implicit (and hence procedural memory) has its own anatomical substrate since it wasn’t affected in H.M: he showed learning on a mirror tracing task.

Question 37

What is implicit memory made up from?

Answer 37

Procedural and priming

Question 38

Edouard Claparede

What is a more controlled version of what he did?

Answer 38

1911 - showed priming to be present in a patient with anterograde amnesia

studied an amnesic woman who never could recall seeing him before but was reluctant to shake his hand after he pricked her finger with a pin

A more controlled test of this is by asking the patient to recognize incomplete pictures and words, and see whether training leads them to recognize progressively more fragmented images.

Question 39

Weiskrantz and Warrington

Answer 39

1970
. A more controlled test of this is by asking the patient to recognize incomplete pictures and words, and see whether training leads them to recognize progressively more fragmented images. Amnestic patients were shown to be able to improve on these tasks by Weiskrantz and Warrington in 1970 – they get better with repetition even after 3 days delay.

Question 40

Discuss priming in patient HM

Answer 40

Priming was also intact in HM – he could learn and improve on incomplete figure tasks.

Question 41

Describe what reconstructive memory is

Answer 41

we reconstruct the past, sometimes based on previous knowledge. (The Loftus and Palmer 1974 paper – “smashed” vs “hit” etc.).

Question 42

What does reconstructive memory have implications on?

Answer 42

This has implications for eyewitness testimony interpretations

Question 43

Wells and Bradfield

Answer 43

1998
In one study people watched an 8 second security video and asked to pick the gunman from photographs. Every observer picked someone despite the fact that none of the people in the photos was the gunman

Question 44

What are confabulations?

Answer 44

false memories without conscious knowledge of their falsehood

Question 45

When can confabulations appear?

Answer 45

after orbitofrontal cortex damage and in Korsakoff’s syndrome