Amnesia

Question 1

Patient HM (Henry Molaison)

Answer 1

Had Bilateral removal of the hippocampus to treat epilepsy

Question 2

What did HM suffer from?

Answer 2

Severe Amnesia
* unable to remember events since operation (anterograde amnesia)
* loss of personal memories up to 11 years prior to surgery (retrograde amnesia)

Question 3

What aspects of HM’s memory were preserved?

Answer 3

• short-term memory
• knowledge of previously-acquired facts (semantic memory)
• motor skill learning; perceptual learning; non-declarative (non-conscious) memory

Question 4

but what was wrong with HM’s brain?

Answer 4

visually all anterior hippocampus and surround cortex removed bilaterally, plus amygdala

Question 5

what happens when there’s damage to the hippocampus?

Answer 5

As the hippocampus is a key part of the network - damage to these associated structures cause amnesia
* there must be bilateral damage affecting these structures in both hemispheres
most patients have less specific damage than HM. This causes a broader range of deficits beyond episodic memory

Question 6

what is the hippocampus linked to?

Answer 6

episodic memory (as decovered from specific brain removal from HM) -> image to hippocampus leads to amnesia but more / less specific damage may lead to broader deficits

Question 7

what does anterior temporal damage lead to?

Answer 7

problems with semantic memory and language

Question 8

what does prefrontal damage lead to?

Answer 8

problems with retrieval and personality

Question 9

what is herpes simplex encephalitis?

Answer 9

Herpes simplex virus spreads from the face along cranial or olfactory nerves to the brain

Question 10

who was affected by HSE?

Answer 10

Clive Wearing and Patient EP (Insausti et al., 2013) are examples of relatively pure cases of amnesia following HSE

Question 11

what does HSE usually affect?

Answer 11

typically focussed in medial and anterior areas (including hippocampus), there is often also damage to anterior temporal and inferior medial frontal cortex.

Question 12

what are the first symptoms of HSE?

Answer 12

fever, confusion, epileptic seizures, anterograde and retrograde amnesia

Question 13

what are later symptoms of HSE?

Answer 13

• semantic deficits (category-specific - trouble with knowledge and name retrieval for animals and people)
• often wide spread damage and deficits

Question 14

What is Hypoxic Brain Injury?

Answer 14

Brain cells start to die after 4-6 minutes of oxygen deprivation. The brain is 2% of the body’s weight yet uses 20% of its oxygen

Question 15

What are the effects of Hypoxic Brain Injury?

Answer 15

individuals who survive an hypoxic episode often have amnesia -> contained to the hippocampus because the brain relies mostly on oxygen here -> quite similar to pure amnesia and only affects episodic memory

• effects of hypoxia are especially severe in the hippocampus as these cells use a lot of oxygen

Question 16

What did Zola Morgan et al., 1986 find as a result of patient RB?

Answer 16

causes of hypoxic brain injury include heart attack, respiratory failure, carbon monoxide posioning and disruption in brain flow to the brain i.e. following a haemorrhage

Question 17

what areas does a hypoxic episode effect?

Answer 17

bilateral hippocampus

Question 18

what do neurones in the hippocampus require oxygen

Answer 18

highly metabolically active so will be particularly affected by oxygen deprivation

Question 19

what are the effects of hypoxic episode?

Answer 19

• pronounced anterograde and some retrograde amnesia
  BUT other mental functions are spared (incl semantic memory and language)

Question 20

What is Korsakoff’s syndrome?

Answer 20

amnesia associated with long-term alcoholism

Question 21

what is Korsakoff’s syndrome caused by?

Answer 21

• thiamine (vitamine B1) deficiency
• Drinkers may neglect their diet
• Alcohol interferes with conversion of thiamine into active form
• Alcohol reduces absorption and storage of vitamins

Question 22

What damage does Korsakoff’s syndrome cause?

Answer 22

Wide-spread damage to the brain: Mammillary bodies are severely affected, plus prefrontal cortex

PFC damage produces problems beyond ‘pure’ amnesia:
* Behavioural changes i.e. apathy
* Problem with retrieval as well as memory formation

Question 23

how can we help retrieval in Korsakoff’s syndrome?

Answer 23

retrieval can be cued

Question 24

How may we be able to treat Korsakoff’s syndrome?

Answer 24

doses of intravenous thiamine (but has to be done quickly)

Question 25

Why don’t those with Korsakoff’s syndrome usually care about treatment?

Answer 25

damaged prefrontal cortex means they have emotional issues (apathy and flat emotional effect) -> don’t really care about treatment as a result of a behavioural change

Question 26

what is Korsakoff’s syndrome often preceded by?

Answer 26

Wernicke’s Encephalopathy

Question 27

What is Wernicke’s Encephalopathy

Answer 27

state of confusion with deficits in motor control
* Anterograde and Retrograde amnesia
* Retrival problems
* Confabulation: difficulty separating real memories from imagination
* Personality changes (apathy and flat emotional affect)

Question 28

what are early symptoms of Alzheimer’s disease?

Answer 28

problems with memory, language, decision-making and planning/reasoning
* some overlap with ‘pure’ amnesia but there is also a deficit in intellectual function

Question 29

What are skills we look at when looking at amnesia?

Answer 29

• Anterograde Amnesia
• Retrograde Amnesia
• Semantic Memory
• Working Memory

Question 30

Anterograde Amnesia

Answer 30

inability to acquire new memories

Question 31

Retrograde Amnesia

Answer 31

loss of memories from before injury

Question 32

Semantic Memory

Answer 32

Factual Knowledge

Question 33

Working Memory

Answer 33

keeping information active by repeatedly think about it

Question 34

Face Recognition [From Wechsler Memory Scale]:
* Patient is shown a sequence of 60 faces, one at a time.
* They are then shown a second sequence of faces and have to decide whether they have seen each one before.
* This is a test of recognition (as opposed to recall). Both recognition and recall are normally impaired in amnesia.
Chance rate is 50%.

What skill does this tap into?

Answer 34

recognition and anterograde memory

Question 35

Picture Naming:
* Patient is shown pictures one at a time and asked to say what they are called. This is a very simple task that gives us a lot of information.
* Some patients can show different degrees of impairment for animals and man-made objects (i.e., category-specific impairment). This might reflect the fact that our knowledge of animals draws heavily on visual features (e.g., the difference between a zebra and a horse is the stripes) while man-made objects have more manipulable features that we feel and move.
* Healthy participants are typically able to name the vast majority of these sorts of pictures – their accuracy is near ceiling.

Errors can be informative:
* Semantic errors – e.g., cat à “dog”
* Phonological errors – e.g., cat à “cad”

What skill does this tap into?

Answer 35

Semantic memory

Question 36

Rey Figure Copy:
The patient first copies the complex figure at the top when it is in front of them. This is the ‘immediate’ condition. 15 minutes later, they are asked to reproduce this figure from memory. To do this, they have to remember seeing the test, so patients with severe amnesia often can’t attempt the delayed copy.

what skill does this tap into?

Answer 36

anterograde

Question 37

Corsi Blocks Test:
* The examiner sits looking at the numbers; the patient is on the other side of the desk and can’t see the numbers. The examiner taps out a sequence on the top of the blocks, such as 2-8-3. The patient then tries to tap the same blocks, in the same order. The sequences start very short (i.e., just two blocks) and get longer. Testing stops once the patient reliably makes errors, and the sequence length that they can reproduce accurately is called their “span”. Healthy participants can tap a sequence of 5-7 blocks.
* This test is often used in conjunction with digit span (repeating a sequence of numbers aloud in the same order you heard them).

What skill does this often tap into?

Answer 37

anterograde

Question 38

Paired-associate learning:
* This is a very simple test that measures verbal learning and forms a core part of the Wechsler Memory Scale (WMS). Participants hear a series of 12 word pairs and then, in the test phase, they hear one of the words and are asked to say the word that was paired with it.
* This test can also be used to distinguish between memory disorders that result from (i) encoding/storage deficits and (ii) retrieval difficulties. If encoding/storage are profoundly impaired, as in HM, the information cannot be recovered even if cues are provided (e.g., what went with Chair – it started with “card….”). However, these cues are very helpful if patients are having difficulty selectively retrieving the right word. We are using this method in our research.

What skills does this tap into?

Answer 38

Anterograde, a bit of working memory and verbal memory

Question 39

Pyramids and Palm Trees (PPT):
The patient is asked to decide which of the two items at the bottom of the page goes with the top item. The trials are presented as either pictures or words. Typically, a patient completes both versions of this test on different days.

What skill does this map into?

Answer 39

anterograde

Question 40

Autobiographical Memory Interview
* The patient is asked to describe a memory that is jogged by each word. For example, if I heard the word RIVER, I might think about the picnic I went on with my friends in Oxford a few years ago when the children were small and how we made a pretend pie with grass seeds.
* An attempt is made to work out when the memories date from – with the help of the patient’s family. The memories from different decades of the patient’s life can then be counted up.
* **The graph shows the normal pattern in red and representative data for a patient with amnesia, who is 46 years old, in blue. Healthy people also tend to report a lot of recent memories, while people with amnesia do not. Both healthy people and those with amnesia show a “reminiscence bump” – lots of memories from the teenage and early adult years; perhaps because memorable things happen in those decades, such as falling in love and leaving home.
* Researchers can also study the quality of memories. My memory about the picnic is detailed and specific, while someone with amnesia might just say “I had some nice food by the river”, which is vague and doesn’t suggest any real recollection.

What skill does this tap into?

Answer 40

Retrograde

Question 41

Which two disorders have broader intellectual problems?

Answer 41

Alzheimer’s and Kor

Question 42

What might be the best test(s) to detect anterograde amnesia and why?

Answer 42

Rey Figure Copy -> isn’t reliant on the individual having sufficient semantic knowledge

Question 43

Who has a severe semantic deficit?

Answer 43

Herpes