Long term memory systems

Question 1

Who was HM? (case study)

Answer 1

■A 19-yr old man suffering from severe epilepsy (abnormal electrical activity in the temporal lobes)
■Scoville’s approach was to cut portions of the right and left medial temporal lobes to stop the seizures
–His successful surgery was in 1953 and the seizures stopped

Question 2

What happened after HM’s surgery?

Answer 2

■HM developed severe memory problems affecting verbal and non verbal info (other cognitive abilities were normal)
■Main problem=retaining new info for more than seconds/minutes
■Past memories (up to 3 years prior to surgery) seemed intact. STM (digit span test) was also normal + could obtain some new skills (e.g. reading mirror inversed text)
■Bilateral medial lobe surgery no longer performed, but unilateral surgery can produce severe amnesia if contralateral MTL is
diseased(not possible if just one side)

Question 3

Why is the case of HM so important?

Answer 3

■First of its kind & well documented + HM took part in numerous scientific studies
■Specific lesions/impairments
described by Scoville in some detail and Lashley’s work suggested that memories were widely distributed across the cortex
■Milner’s later work on patients with unilateral MTL lobectomies revealed content specific
memory deficits:
Left MTL=more responsible for verbal memories
Right MTL=more responsible for non-verbal (pictorial and spatial) memories

Question 4

What type of amnesia did HM have?

Answer 4

A “pure” form of organic amnesia

Question 5

What areas of the brain are damaged in amnesia?

Answer 5

■Medial temporal lobes(including the hippocampus+adjacent cortical areas i.e., parahippocampal cortex, perirhinal cortex)
■Thalamus (Anterior and dorsomedial nuclei)
■Fornix (fibres in back of hippocampus) & Mammillary bodies
■Basal forebrain
■Interconnected structures

Question 6

Define Anterograde amnesia (Organic amnesia)

Answer 6

Impaired memory of events and facts experienced AFTER the onset of amnesia (varying from mild to severe)

Question 7

Define Retrograde amnesia (Organic amnesia)

Answer 7

Impaired memory of events and facts learned BEFORE the onset of amnesia (covering either an extensive or very short period of time)

Question 8

What is preserved in organic amnesia?

Answer 8

■Intelligence, perception, attention and language (but depending on the causation and extent of brain damage, some patients might have additional problems)
■Some forms of learning and memory e.g., new skills, classical conditioning and priming
■ST and WM (can retain and process a small amount of info for a brief period of time e.g., digit span task and can manipulate info)

Question 9

What tasks were used to test preserved memory in HM & other amnesics?

Answer 9

1.The tower of Hanoi task
2.Pursuit rotor task
3.Mirror tracing task

Question 10

How is LTM organised?

Answer 10

■Memory is related but distinct from information processing
–Type of info processing affects memory encoding (You can be intelligent and amnesic)
■LTM isn’t a unitary structure, there are multiple forms or expressions of LTM that are anatomically dissociable (i.e., different brain areas)
■New classification of LT memories based on whether they involve conscious retrieval (Declarative/Explicit vs. Nondeclarative/Implicit)

Question 11

Explain what declarative or explicit memories are

Answer 11

■What we intuitively regard/perceive as memory
■Retrieves info consciously
■Depends somewhat on structures damaged in amnesia (MTL, diencephalon, basal forebrain)

Question 12

Explain what nondeclarative or implicit memories are

Answer 12

■Assessed by changes in behaviour implicitly learning (i.e., past experience with certain items/actions makes us more accurate, faster/efficient in processing the items or performing the actions)
■Unconscious
■Can’t be directly accessed/ manipulated (i.e. can’t explain to people how to ride a bike)
■Involve structures not damaged in amnesia

Question 13

Give 2 examples of Declarative/Explicit memory

Answer 13

episodic and semantic memory

Question 14

Explain what episodic memories are

Answer 14

*Stores/retrieves specific events (usually personal e.g. 1st day of school)
*Linked to a specific place/time
*Involves conscious recollection
*Provides answers to What? When? and Where?

Question 15

What unique features does episodic memory contain?

Answer 15

■A subjective sense of time + ability to time travel to the past and to the future. (i.e. reflect)
■Involve a sense of “self” attached to the person who remembers (Ownership of the memory)
■Autonoesis or autonoetic consciousness=the awareness that characterises the conscious recollection of personal episodes.
–Semantic memory is accompanied by noetic consciousness (i.e. you know something but without the personal, intimate feeling)

Question 16

Dissociating episodic from semantic memories: Developmental Amnesia (Elward & Vargha-Khadem, 2018)

Answer 16

-Some individuals who suffered perinatal brain injury (e.g. anoxia) show episodic memory deficits but can acquire semantic knowledge.
-Impairments in episodic tests free recall, paired-associate learning, and recognition but able to acquire language and general knowledge (Attend mainstream schools although they are unable to learn at the same rate as
controls.)
-tend to have lesions in the hippocampus but the rest of
the brain could be relatively intact.

Question 17

What evidence is there for episodic memory deficits to demonstrate the impacts?

Answer 17

Vargha-Khadem et al. 2007:
-3 young people who suffered hippocampal damage at a
young age showed impaired recall memory + memory for new
associations despite having IQ scores and semantic knowledge
within the normal range
-Impairments in visual recall in the Rey-Osterreith Complex Figure test + verbal recall of short stories

Question 18

Give evidence dissociating episodic from semantic memories

Answer 18

Organic amnesics tend to have bigger impairments in episodic than semantic memory
147 amnesics with damage to hippocampus/fornix (memory for learning AFTER amnesia onset):
100% had episodic memory impairments but often only modest semantic impairments (Spiers et al., 2001)
 BUT, acquisition of new semantic knowledge in adult onset amnesia (unlike developmental amnesia) is severely impaired

Question 19

Define semantic dementia

Answer 19

the widespread forgetting of meanings of words and concepts
–damage to anterior temporal lobes=severe impairments of semantic memory
–Relatively intact episodic memory at early stages of semantic dementia (Landin-Romero et al., 2016)

Question 20

What support is there for independent episodic and semantic memory?

Answer 20

–Double dissociation between amnesia (worse episodic memory than semantic memory) and semantic dementia (worse semantic memory than episodic memory
–BUT double dissociation only approximate

Question 21

What support is there for interdependent episodic and semantic memory?

Answer 21

–Episodic memory can aid the acquisition of semantic memories. (Controls learn faster than individuals with developmental amnesia)
–Semanticisation of episodic memory: Shift from detail-rich episodic memories to gist-like semantic memories over time (Robin & Moscovitch, 2017).

Question 22

Our ability to retrieve episodic memories is based on what two processes?

Answer 22

Recollection and Familiarity.

Question 23

Define Recollection

Answer 23

our ability to remember specific details (what/where/when) and/or mentally travel back in time to the experienced event. It is a slower, more attention and effort demanding process.

Question 24

Define Familiarity

Answer 24

the sense of knowing something, the feeling that something has
been previously experienced but without being able to remember any details. It is a faster and “automatic” (not effortful).
Recall=primarily recollection based
Recognition=recollection and familiarity based

Question 25

What is the Remember/Know paradigm?

Answer 25

Recognition followed by subjective judgements of Remember (recollection) or Know (familiarity)

Question 26

Explain the Binding-of-item-and-
context model (Diana et al., 2007)

Answer 26

Perirhinal cortex=receives info about specific items (“What” info is needed for familiarity judgements)
Parahippocampal cortex=receives info about context (“Where” info useful for recollection judgements)
Hippocampus=binds “what” and “where” info forming item-context associations

Question 27

Explain the two complimentary behavioural-anatomical systems involving both MTL and
diencephalic structures

Answer 27

Recollection/episodic: Hippocampus, fornix, anterior thalamus, mammillary
bodies
Familiarity/non episodic=Perirhinal, cortex, dorsomedial thalamus
■ The systems involve a network of structures
–one part of the network is affected=stops working
■The two systems are independent but interacting
–Damage of one system does not stop the other from operating

Question 28

What findings support the dual process models?

Answer 28

Neuroimaging identifies the predicted brain areas associated with familiarity and recollection
judgements (Diana et al., 2007)
Amnesics with damage to hippocampus and connected structures have greater impairment to recollection than to familiarity judgements (Tsivilis et al., 2008; Vann et al., 2009)
Patients with damage to perirhinal cortex have greater impairment to familiarity than recollection judgements (Bowles et al., 2011)

Question 29

What’s the link between mammillary bodies and memory? (Tsivilis et al 2008)

Answer 29

• Mammillary bodies show atrophy following fornix damage
• The size of the mammillary bodies predicts memory performance in colloid
  cyst surgery patients
  Large mammillary body (LMB) volumes=better at recall (recollection network) than patients with SMB volumes
  no difference for recognition (which could also be supported by the familiarity network)
  same patients showed a deficit in recollection but not familiarity when tested at the remember/know task (Vann et al. 2009)

Question 30

What did Patai et al (2015) find in comparing recall and recognition?

Answer 30

-similar dissociations between
recall and recognition in patients with hippocampal damage (perinatal complications reducing volume)
* IQ, literacy, and numeracy scores within normal range but episodic memory (MQ) was impaired
*Recall but not recognition scores correlated with hippocampal volume (higher volume=better recall)

Question 31

What’s the role of the perirhinal cortex?

Answer 31

■Patient NB: resection of parts of the left perirhinal cortex (Bowles et al. 2008)
■Impaired familiarity memory but unaffected recollection memory
■Shows a double dissociation between the functional effects of hippocampal and perirhinal damage.

Question 32

What are some limitations of dual-process models?

Answer 32

Some patient studies show equivalent impairments in recollection and familiarity after
hippocampal damage (Bird, 2017)
 Single-process models of recognition memory suggest that the distinction between recollection and
familiarity is based on strength of underlying memory not of quality (Geurten & Willems, 2017)
Single models of recognition memory suggest that the MTL has a single function: familiarity.
-focuses too much on MTL and does not identify all brain mechanisms and areas involved in recognition memory (e.g., the role of the frontal and particularly parietal lobes in memory.)

Question 33

What did Manns and Squire (1999) find testing six anoxic hippocampal patients on the Doors and People test?

Answer 33

found impairments in both visual and verbal recall and recognition.

Question 34

What does Ribot’s Law state?

Answer 34

in cases of memory damage, the older the memory the less likely it is to be affected. (A temporally graded retrograde amnesia as in HM)

Question 35

Explain The Consolidation theory (Squire & Alvarez, 1995)

Answer 35

■Initially, memories depend on connections between the hippocampus and cortical
sites (where memories are stored)
■Consolidation=memories undergo a constant change from the point of acquisition (gradual strengthening of cortico-cortical connections)
■This is an unconscious automatic process maybe related to activity during sleep.
■Although required in recent memory retrieval, the hippocampus becomes non-essential in the retrieval of remote memories.

Question 36

The Consolidation theory (Squire & Alvarez, 1995): What are the impacts of hippocampal damage?

Answer 36

-Recent memories affected more than remote, with memories in between showing degrees of impairment proportionate to time since acquisition (Ribot’s gradient)
■More extensive hippocampal damage (affecting adjacent cortical areas or frontal cortex) should produce flat gradients.

Question 37

What are 2 unclear things within the consolidation theory?

Answer 37

1.Unspecified period for consolidation to complete (could be decades?)
2.Unclear mechanism by which long-term consolidation is achieved.

Question 38

Explain The Multiple Trace Theory (MTT) (Nadel & Moscovitsch, 1997)

Answer 38

■Hippocampus doesn’t have a time-limited role in memory.
■Hippocampus essential for episodic memory retrieval irrespective of a memory’s age.
■MTT predicts that complete hippocampal damage should affect all remote memories=flat gradient.
■It also suggests that evidence of temporal gradients (Ribot’s gradients) not a result of
consolidation but replication of hippocampal traces over time.
■Re-encoding of older memories=new hippocampal traces. Incomplete hippocampal lesions will affect recent memories (weaker traces/connections) more than remote memories (stronger+more traces/connections) in a probabilistic manner.

Question 39

Explain what Cipolotti et al. (2001) found on patient VC

Answer 39

-patient VC amnesic at 67 due to several epileptic seizures + episodes of tachyrythmia. Substantial hippocampal atrophy (a).
■ VC had severe AA accompanied by severe RA.
■Remote memory for facts (public events [b] e.g.) was impaired (recognition was better than recall).
■Remote autobiographical memories were also severely affected (c).
■No evidence of a temporal gradient; impairment affected all periods of life (although remote semantic memories seem to show some preservation).

Question 40

What’s the flaw with investigating autobiographical memory and why is it problematic?

Answer 40

–They ask P’s to provide them with incidents from their past which are then asked to fully recall in the scanner.
■This is problematic as:
–Memories are self-selected
–Activity may become contaminated by this procedure which makes people rethink their memories.
■Gilboa et al (2004) avoided this by asking friends and relatives of the P’s to provide pictures relating to autobiographical events.

Question 41

What have Retrospective Neuroimaging studies found?

Answer 41

■Both remote and recent memories triggered by personal photos activating the hippocampus.
■Remote memory activations have a widerspread distribution than recent memories.
■Recent memories produced greater hippocampal activity than remote ones (the difference disappeared when controlled for vividness.)
■Hippocampus was modulated by change in the vividness of memories>the passage of time.

Question 42

What did Bayley et al (2005) find in relation to temporal gradients?

Answer 42

-previous findings of temporal gradient in patients with selective
hippocampal damage not due to task insensitivity.
■ Remote memories in selective hippocampal patients were as vivid, full of recollective details and personal as in the controls (not supporting MTT)
■Therefore more studies are needed to explain the discrepancies across studies

Question 43

Define Priming (Non-declarative memory)

Answer 43

the facilitated processing of repeated stimuli (becoming more fluent, accurate, faster or generally better at processing the same or items similar to those we have experienced previously)
■doesn’t require conscious recollection of the learning experience (becomes
evident in our performance)

Question 44

Define Perceptual priming

Answer 44

repeated stimulus presentations enhances perceptual processing

Question 45

Define Conceptual priming

Answer 45

repeated stimulus presentations enhances processing of stimulus
meaning
■Priming often occurs rapidly + learning tied to specific stimuli
■Amnesic patients typically have reasonably intact priming (e.g. Oudman et al., 2015)

Question 46

Give an example of a semantic priming task

Answer 46

Study:table, guitar, apple, sofa, train
Test:Write down the first type of fruit that comes to mind
Priming:People are more likely to say apple when they have just seen apple than if they had not

Question 47

Give an example of a repetition priming task: speed of processing

Answer 47

Study:cherry guitar goat sofa train
Task: living or non-living
Test:cherry goat guitar parrot sugar (some the same/some new)

Reaction times to Repeated<New

Question 48

Give general facts about priming & the brain

Answer 48

■Priming activity: Primed – Novel (unprimed)
■Priming activity involves a subset of processing areas
–There is no single locus of priming.
–Several different processing stages can be facilitated by repetition (orthographic,
phonological, semantic etc.)
■Priming activity is often reduced compared to activity generated by non-primed items
– Primed<Novel

Question 49

What does neuroimaging studies of object priming show?

Answer 49

Novel (unprimed) more brain activity > fixation
Repeated (primed) more brain activity > fixation
Unprimed more brain activity>primed
C=Right extrastriate cortex-object representation
D=Left dorsal frontal cortex (IFG)-covert naming

Question 50

What do neuroimaging studies of priming show?

Answer 50

■Perceptual and conceptual priming depend on partially distinct neural networks.
■CP activates an area in the inferior frontal gyrus (dorsal & inferior prefrontal cortex) implicated in semantic processing (A and B on the maps)
■PP activates areas in the extrastriate cortex also responsible for higher-level perceptual analyses (C and D on the maps).

Question 51

Explain theoretical accounts of repetition suppression: (Wiggs & Martin, 1998).

Answer 51

-repetition suppression is due to a
“sharpening” of the underlying representation.
-Task-irrelevant info (represented as white circles) is no longer activated over trials
-At neurophysiological level that takes the form of reduced neuronal firing whereas behaviourally is represented by reduction in response times

Question 52

Explain theoretical accounts of repetition suppression: (Henson & Rugg, 2003)

Answer 52

-repetition suppression is due
to lowered thresholds for activating, pre-existing
representations.
-only familiar stimuli with pre-
existing representations can be primed

Question 53

Explain Procedural memory (nondeclarative memory)

Answer 53

Knowing how to perform various actions (especially skilled)
Procedural learning occurs slowly generalising to stimuli not presented during learning.
Amnesic patients typically have reasonably intact skill learning and procedural memory (Oudman et al., 2015).
Procedural learning is nondeclarative (e.g. learning to ride a bike/swim).
Some forms of procedural learning involve initial declarative learning before they become nondeclarative through practice (e.g. learning to drive)

Question 54

State the numerous types of skill learning as identified by Foerde and Poldrack (2009)

Answer 54

 motor skill learning
 sequence learning
 mirror tracing
 perceptual skill learning
 mirror reading
 probabilistic classification learning (involves the striatum)
 artificial grammar learning
Different brain parts will be involved in procedural memory depending on the processes
required to learn new skills.

Question 55

Explain Skill learning

Answer 55

■Probabilistic learning
■Learning to associate specific card combos with a specific outcome
■People with basal ganglia damage like Parkinson’s disease patients are impaired in this task
■The same areas are more active when the task is implicit (i.e. no need to memorise the combination-outcome association) and with an inactive MTL
■When the task is made explicit (people encouraged to remember the combination-outcome association), the pattern of activity reverses.