Lecture 13 - Amnesia

Question 1

Defined memory

Answer 1

Memory is retention of learnt information

Question 2

Karl Lashley (1920) conducted an experiment to see where memory was stored. Explain the principle of this experiment, what he did to test his hypothesis and what he found.

Answer 2

Principle: he trained rats to run in maze from start to finish line

He removed different areas of the cortex to see which area was affected

Result: removal of cortex area impaired memory; area of cortex removed correlated with severity of impairment

Question 3

Karl Lashley’s experiment was later improved by Hebb’s postulate: neurons that fire together wire together.
Describe Hebb’s theory of cell assembly and memory storage

Answer 3

1. External stimulus activates specific cell assembly
2. Reverberating activity continues after removal of the stimulus (the reverberating activity is responsible for working memory)
3. Hebbian modification: strengthen connections of the cell assembly containing the engram of the stimulus
4. Strengthened connections contained the engram of the stimulus

Question 4

The famous case of HM which had his temporal lobes removed bilaterally.
State what type of amnesia affected HM post surgery and explain what sort of tests you can conduct to test anterograde and retrograde memory.

Answer 4

1. Anterograde amnesia: HM could not form new LONG TERM memories

TEST: recall and recognition tests with words and pictures

2. Partial Retrograde amnesia: HM could not recall long term memories formed during a period before trauma

TEST: Famous faces test, autobiography memory interview, News events, TV programmes

Question 5

Autobiography memory interview allows you to tap both into semantic and episodic memory. Explain the differences between semantic and episodic memory

Answer 5

Semantic memory: facts of the world; 12 months in a year

Episodic: recollection for specific events

Question 6

What structure of the medial temporal lobe in HM was damaged?

Answer 6

• Hippocampus
• Amygdala
• Rhinal cortex (entorhinal, perirhinal and parahippocampal)

Question 7

In context of long term memory, what aspect of long term memory (recall and formation) is impaired in anterograde and retrograde amnesia patients?

Answer 7

anterograde: inability to FORM new long term memory
retrograde: inability to RECALL old long term memories

Question 8

State the differences between short term and working memory

Answer 8

Short term: storing a small information over a very brief interval

• Can be disrupted by distraction (susceptible to interference)
• Limited capacity

Working memory: a system for the temporary maintenance and manipulation of information
- Requires repetition to remember

Question 9

Although HM does suffer some aspect of his long-term memory what other aspect(s) that are NOT impaired in HM long term memory?

Answer 9

• Mirror drawing (motor skill)
• Mirror reading (cognitive skill)
• Priming

Question 10

Describe the two divisions in long-term memory and further subdivisions if any

Answer 10

• Declarative: semantic and episodic

- Non-declarative: procedural memory