Memory Disorder

Question 1

What are the two types of amenia?

Answer 1

organic and Functional

organic subdivided into:
degenerative disease
acute damage to the brain
functional: purely psychological

types: retrograde and anterograde
Retrograde amnesia: can’t remember memories leading up to the onset of amnesia

Anterograde amnesia: can’t rememember memories post amnesia

Question 2

what are the main features of amnesic syndrome?

Answer 2

Isolated to memory loss
Refers to amnesia caused by organic causes of amnesia something that has acutely happened to the brain
Pronounced anterograde amnesia (inability to form memories for events encountered after the onset of amnesia)
2. Variable retrograde amnesia (inability to retrieve memories acquired before the onset of amnesia).
3. Intact short-term memory (STM), e.g., digit span task
4. Preserved general intelligence (IQ)
5. Skills such as driving and playing music unaffected
6. Some residual learning capacity `

Question 3

Outline the causes of organic amnesia

Answer 3

Biological (damage to the brain)

What parts of the brain are important for memory
Amygdala- emotional content of episodic memory
Basal ganglia – important for learning motor skills
Cerebellum- automatised skills
Frontal lobes- working memory, central executive, source monitoring; prospective memory
Occipital lobes (Visual Perceptual representation memory)
Humans and other mammals have 2 hippocampi
Curled structures, deep in the brain
Key for forming and retrieval of episodic memories

Question 4

give the case study of HM

Answer 4

Operated to remove the medial temporal lobes - 2/3rd of hippocampus
Fixed epilepsy
Caused amnesia
Personality unchanged
IQ went up
Unable to form new episodic memories – severe anterograde amnesia
Also developed selective retrograde amnesia- around 10-15 years leading up to surgery
Still normal: stm and learning of new procedural memories

Question 5

what is Korsakoof’s syndrome?

Answer 5

Caused by thiamine deficiency (usually due to alcoholism)
Damage to diencephalon in particular
Patients appear to be drunk, uncoordinated, confused

Amnesia in Korsakoff’s syndrome:
STM is normal
Formation of new LTM memories impaired (anterograde)
Retrograde amnesia streaching abck years

Temporal gradient of retrograde amnesia: Recall for events in the time immediately leading up to its onset very poor, but earlier memories relatively intact

Question 6

what is Viral Encephalitis

Answer 6

Caused by herpes crossing the blood brain barrier
Sudden onset of acture fever, headache, nausea
Usually extensive bilateral temporal lobe damage

Question 7

describe amensia caused by VE

Answer 7

Particularly severe amnesic disorder ( e..g clive wearing)
Similar to Korsakoff’s but better insight, and flatter temporal gradient- early memories may also be lost
Often deficits of spatial and semantic memory e.g. surface dyslexia, facial recognition issues -> connected with hippocampus

Anterograde amnesia

Question 8

outline amensia due to dementia

Answer 8

demnetia
common types:
• Alzheimer’s disease - 62%
• Vascular (multi-infarct) - 17%
• Mixed Alzheimer’s & Vascular - 10%
• Lewy Body dementia - 4%
• Fronto-temporal dementia (including Pick’s) - 2%
• Parkinson’s Disease Dementia – 2%
• Other (including alcohol-related) - 3%
• Each type associated with distinct brain changes, evident at post-mortem
Each type is associated with distinct brain changes, evident at post-mortem

Oldest groups most at risk (90+)

Women moreso at risk than men
Progressive neural disease

General degeneration of the brain; atrophy due to growths of neural plaques and tangles

Question 9

describe an early case of dementia

Answer 9

In 1907, Alois Alzheimer described the case of Auguste D. (died aged 55)
• Memory loss, disorientation, hallucinations
• ‘an unusual disease of the cerebral cortex’

Question 10

give an example of how dementia occur due to pharmacutical side effects

Answer 10

viagra causes transient global amnesia

Question 11

outline TGA

Answer 11

Isn’t just caused by drugs

Sudden onset of anterograde amnesia as well as retrograde amnesia for recent events preceding attack. • No loss of personal identity; recognise family members
• Anxious, agitated, repetitive questioning
• Resolves within 12 hrs; mean duration of 4 h
• Fairly rare 5-30/100,000
• Mostly over 50s, more often men- history of migraine patients
• Triggers include emotional upset, vigorous exercise or pharmaceuticals
• don’t know exact cause but could be caused by disruption of blood flow to thalamic/medial temporal cortex

Question 12

outline psychogenic amnesia

Answer 12

Amnesia that is not due to organic factors (much less common than organic amnesia

Amnesia that is not due to organic factors (much less common than organic amnesia
2 types: fugue states and dissociative states
Fugue states:
Amnesia including loss of identity
This type of amnesia is the one most commonly depicted in the TV/movies e.g. bourne films
Fugue states:
Sufferer typically found wandering, often a long way from home.
• Triggers include severe stress, depressed mood, history of transient organic amnesia (Kihlstrom & Schacter, 1995).
• Lasts a few hours or days (can be longer).
• After recovery, memories from the fugue state are lost.
• Very rare.
2 types: fugue states and dissociative states

Question 13

outline fugue states

Answer 13

Sufferer typically found wandering, often a long way from home.
• Triggers include severe stress, depressed mood, history of transient organic amnesia (Kihlstrom & Schacter, 1995).
• Lasts a few hours or days (can be longer).
• After recovery, memories from the fugue state are lost.
• Very rare.

Question 14

Outline the Dissociaitve types of psychogenic amnesia

Answer 14

• Refers to loss of memory for specific events due to trauma (no anterograde amnesia).
• 25-45% of homicide suspects claim amnesia for crime.
• No cases reported before 1800: “dissociative amnesia is not a natural neuropsychological phenomenon, but instead a culture-bound syndrome, dating from the 19th century” (Pope et al., 2007).
• Your chance to make $1000!**
• These types of psychogenic amnesia are extraordinarily rare (though much more common in fiction!).
• Very difficult to rule out malingering as a possible cause.
• ** $1000 was recently awarded to someone who nominated Nina, an opera performed in Paris in 1786

Question 15

how can amnesia point to different types of memory?

Answer 15

Amnesia provides evidence for disoocisation between STM and LTM
Amnesic have poor episodic memory, and often (though, not always) have poor semantic memory, but:
Show normal priming effects
Still have motor memory (skills) (procedural)
Can also learn new peocedural skills
Shows the dissociation between explicit memory and implicit memory
Explicit tests: free recall and recognition: amnesiacs perform worse
Implicit tests: word fragment identification and word stem completion: no significant difference

Question 16

give the theories of antergorade amnesia

Answer 16

• Why can’t amnesiacs form new episodic memories?
• Several theories have been considered, including:
1) Faulty encoding
2) Accelerated forgetting
3) Faulty retrieval
4) Faulty encoding/storage of contextual information

Question 17

give the theory of intial encoding cauign retrograde amensia

Answer 17

Problem with initial encoding?

• Cermak (1979): amnesic deficit due to lack of deep encoding, e.g., bad at learning word pairs like hungry-thin (cf. Levels of processing theory)
• However, Meudell, Mayes, and Neary (1980) found similar levelsof-processing effect in amnesics and normals.

Question 18

give the theroy of accelerated forgetting

Answer 18

• Some studies show that patients with hippocampal lesions forget faster than controls, even after material has been adequately learned (Huppert & Piercy, 1979; Squire, 1981).
• In other studies various different types of amnesics forget at the same rate as controls, provided initial learning is adequate (Huppert & Piercy, 1978; Squire,1981; Kopelman,1985).

Question 19

give the theory of retrieval deficit

Answer 19

Transient amnesia shows that retrieval deficits can cause amnesia – once amnesia resolves, memories that were unavailable can be retrieved normally (Kritchevsky, 1992).

• But what kind of retrieval deficit are we talking about?
• Clue is offered by difference between recognition and recall. Recognition is sometimes unimpaired in amnesics (Aggleton & Shaw, 1996), but recall is always impaired.
• Warrington and Weiskrantz (1970) suggested that retrieval deficit is due to response competition. Partial information (e.g., 1st letter of studied word) helps overcome competition.
• Meudell et al. (1978): amnesics made four times as many intrusion errors as controls (interference from previous list).

Question 20

outline faulty encoding/retrieval of contextual info as a cause of amnesia

Answer 20

Could retrieval difficulties be related to absence of contextual information?

• Contextual information allows us to distinguish between otherwise similar memories
• Encoding specificity principle: LTM is generally better when context at retrieval and encoding match.
• Huppert and Piercy (1976): Amnesia due to inability to encode and retrieve contextual information…

Question 21

Outline Hupert and Peicy’s test of contextual defict theory

Answer 21

METHOD Two groups: Amnesic (Korsakoff patients) and Normal controls. Presented a set of pictures on Day 1 and a set of pictures on Day 2. Some were presented on both days. Recognition test after Day 2 pictures.
Both groups asked to do 2 tasks:
1. ‘Ever seen recognition’: Say ‘yes’ if the pics had been seen at all (i.e., regardless of which day)
2. ‘Day 2 recognition’: Say ‘yes’ if the pics had been seen only on Day 2

Question 22

give the issues with CDT

Answer 22

1. Semantic memories can also be impaired, but these are not contextual.
2. Definition of context is vague
3. Why remember a stimulus but not its context?
4. Context-processing deficits vary substantially across patient groups (e.g., Parkin & Hunkin, 1997; Squire, 1982).

Contextual deficit unlikely to be the whole story …

Question 23

give the explanation for temporal gradient in retrograde amnesia

Answer 23

Ribot’s (1881) law of retrograde amnesia: recent memories are more likely to be lost (opposite of forgetting)
Temporal gradient may be due to slowscale consolidation processes => earlier memories have had longer to be consolidated

Question 24

explain the consolidation theory of retrgodrade amnesia

Answer 24

• Patients like HM have retrograde amnesia stretching back 10-15 years. Could this reflect the time of consolidation processes?
Standard Consolidation Theory
• Squire (1992); Dudai (2004)
• Episodic memories are initially encoded and stored in hippocampus, and retrieving these memories requires reactivating the hippocampus
• Over time, the hippocampal memory trace becomes less important, and the cortex can retrieve the memory without the hippocampus
• Consequently, older memories are spared in retrograde amnesia