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Amnesia What is it

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Loss of memory ability - usually due to lesion or surgical removal of various ... Patient H. M. - bilateral resection of medial temporal lobes (containing hippocampus) ... – PowerPoint PPT presentation

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Title: Amnesia What is it


1
Amnesia What is it?
2
Memory
3
Proposed Types of Memory
4
Amnesia
  • Loss of memory ability - usually due to lesion or
    surgical removal of various parts of the brain

5
Amnesia
  • Loss of memory ability - usually due to lesion or
    surgical removal of various parts of the brain
  • Two broad categories
  • Retrograde loss of memories for events prior to
    damage

6
Amnesia
  • Loss of memory ability - usually due to lesion or
    surgical removal of various parts of the brain
  • Two broad categories
  • Retrograde loss of memories for events prior to
    damage
  • Anterograde loss of ability to store new
    memories of events after damage

7
Amnesia
  • Short-term and sensory memory are typically
    functional

8
Amnesia
  • Amnesia patients exhibit recency effect but not
    primacy effect

9
Causes of Amnesia
  • Concussion
  • Migraines
  • Hypoglycemia
  • Epilepsy
  • Electroconvulsive shock therapy
  • Specific brain lesions (i.e. surgical removal)
  • Ischemic events
  • Drugs (esp. anesthetics)
  • Infection
  • Psychological
  • Nutritional deficiency

10
Amnesia - associated brain regions
  • Diencephalic amnesia - damage to the medial
    thalamus and mammillary nuclei

11
Amnesia - associated brain regions
  • Diencephalic amnesia - damage to the medial
    thalamus and mammillary nuclei
  • Medial temporal lobe amnesia - damage to the
    hippocampal formation, uncus, amygdala, and
    surrounding cortical areas

12
Amnesia - associated brain regions
  • Diencephalic amnesia - damage to the medial
    thalamus and mammillary nuclei
  • Medial temporal lobe amnesia - damage to the
    hippocampal formation, uncus, amygdala, and
    surrounding cortical areas
  • Other implicated regions include Anterior Lateral
    Temporal Lobe and Frontal Lobes

13
Amnesia
Thalamus
Hippocampus
14
Diencephalic Amnesia
  • Damage to the medial thalamus and/or mammillary
    bodies
  • stroke
  • Korsakoffs syndrome
  • Caused by thiamine deficiency as a result of
    chronic alcoholism

15
Korsakoffs Syndrome
  • The Lost Mariner - What happened to Jimmie? What
    was his life like?

16
Korsakoffs Syndrome (The Lost Mariner)
  • Lesions to Medial Thalamus
  • Results from chronic alcoholism and consequent
    thiamine deficiency

17
Korsakoffs Syndrome (The Lost Mariner)
  • Lesions to Medial Thalamus
  • Results from chronic alcoholism and consequent
    thiamine deficiency
  • Severe anterograde amnesia

18
Korsakoffs Syndrome (The Lost Mariner)
  • Lesions to Medial Thalamus
  • Results from chronic alcoholism and consequent
    thiamine deficiency
  • Severe anterograde amnesia
  • Severe retrograde amnesia extending years before
    damage

19
Korsakoffs Syndrome (The Lost Mariner)
  • Lesions to Medial Thalamus
  • Results from chronic alcoholism and consequent
    thiamine deficiency
  • Severe anterograde amnesia
  • Severe retrograde amnesia extending years before
    damage
  • Confabulation - make up stories to explain
    absence of memory

20
Korsakoffs Syndrome (The Lost Mariner)
  • Lesions to Medial Thalamus
  • Results from chronic alcoholism and consequent
    thiamine deficiency
  • Severe anterograde amnesia
  • Severe retrograde amnesia extending years before
    damage
  • Confabulation - make up stories to explain
    absence of memory
  • Often unaware of their deficit

21
Medial Temporal lobe amnesia
  • Hippocampus is most important site of damage

22
H. M.
  • Patient H. M. - suffered from extreme epilepsy

23
H. M.
  • Patient H. M. - bilateral resection of medial
    temporal lobes (containing hippocampus)
  • William Beecher Scoville and Brenda Milner - late
    1950s

24
H. M.
  • Patient H. M. - bilateral resection of medial
    temporal lobes (containing hippocampus)
  • William Beecher Scoville and Brenda Milner - late
    1950s
  • Severe anterograde amnesia

25
H. M.
  • Patient H. M. - bilateral resection of medial
    temporal lobes (containing hippocampus)
  • William Beecher Scoville and Brenda Milner - late
    1950s
  • Severe anterograde amnesia
  • Retrograde amnesia for 1 - 3 years before surgery

26
H. M.
27
H. M.
  • Patient H. M. - bilateral resection of medial
    temporal lobes (containing hippocampus)
  • William Beecher Scoville and Brenda Milner - late
    1950s
  • Severe anterograde amnesia
  • Retrograde amnesia for 1 - 3 years before surgery
  • Disconnection of autonomic responses such as
    hunger/satiety and Galvanic Skin Response (GSR)

28
H. M.
  • Some aspects of memory were spared (at least to
    some extent)

29
H. M.
  • Some aspects of memory were spared (at least to
    some extent)
  • Procedural memory was largely unaffected -
    amnesia was largely restricted to episodic memory

30
H. M.
  • Some aspects of memory were spared (at least to
    some extent)
  • Procedural memory was largely unaffected -
    amnesia was largely restricted to episodic memory
  • Some implicit awareness of recent events

31
H. M.
  • Some aspects of memory were spared (at least to
    some extent)
  • Procedural memory was largely unaffected -
    amnesia was largely restricted to episodic memory
  • Some implicit awareness of recent events
  • Normal digit span (short-term memory) !

32
E. P.
  • Suffered acute viral disease in brain
  • Damage sustained in temporal lobes, notably the
    hippocampus

33
E. P.
  • Suffered acute viral disease in brain
  • Damage sustained in temporal lobes, notably the
    hippocampus
  • Displays anterograde amnesia
  • Short term memory intact
  • Lives in a permanent present

34
E. P.
  • Suffered acute viral disease in brain
  • Damage sustained in temporal lobes, notably the
    hippocampus
  • Displays anterograde amnesia
  • Short term memory intact
  • Lives in a permanent present
  • What else can we infer from the interview seen?

35
Hypermnesia - S.
  • Photographic extreme memory ability (a
    mnemonist)

36
Hypermnesia - S.
  • Photographic extreme memory ability (a
    mnemonist)
  • Able to recall complex test stimuli

37
Hypermnesia - S.
  • S. used two strategies or abilities typical of
    mnemonists
  • Rich synesthesia-like quality to his perception
    of stimuli - leads to stronger associative links

38
Hypermnesia - S.
  • S. used two strategies or abilities typical of
    mnemonists
  • Rich synesthesia-like quality to his perception
    of stimuli - leads to stronger associative links
  • Vivid and elaborate mental imagery of things he
    should remember

39
Hypermnesia - S.
  • Even numbers remind me of images. Take the
    number 1. This is a proud, well-built man 2 is
    a high-spirited woman 3 a gloomy person (shy, I
    dont Know) 6 a man with a swollen foot...

Luria, A.R. The mind of a mnemonist.
1968 Luria, A.R. The man with a shattered world.
1972
40
Amnesia
  • What pattern of result can be seen across these
    patients cases? What does it suggest about
    memory systems?

41
Dissociation of Memory Systems
  • Memory systems are doubly-dissociated

42
Dissociation of Memory Systems
  • Memory systems are doubly-dissociated
  • Patient H.M.s lesion affected only episodic
    long-term memory - semantic and procedural memory
    were intact - short-term memory was intact

43
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