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Amnesia - What is it?. A selective disruption of the processes underlying long-term memory Short-term and sensory memory are typically functional Other cognitive functions are not impaired Intelligence, attention. Amnesia - What is it?.

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amnesia what is it
Amnesia - What is it?
  • A selective disruption of the processes underlying long-term memory
  • Short-term and sensory memory are typically functional
  • Other cognitive functions are not impaired
    • Intelligence, attention...
amnesia what is it2
Amnesia - What is it?
  • A selective disruption of the processes underlying long-term memory
  • Short-term and sensory memory are typically functional
  • Other cognitive functions are not impaired
    • Intelligence, attention...
recency vs primacy
Recency vs Primacy
  • Amnesia patients exhibit recency effect but not primacy effect

Long-term

memory

Short-term

memory

amnesia what is it4
Amnesia - What is it?
  • A selective disruption of the processes underlying long-term memory
  • Short-term and sensory memory are typically functional
  • Other cognitive functions are not impaired
    • Intelligence, attention...
retrograde anterograde
Retrograde & Anterograde
  • Retrograde amnesia - Loss of information that was learned before the onset of amnesia
  • Anterograde amnesia - inability to learn new information after the onset of amnesia
  • Both can occur in the same patient and commonly do
retrograde anterograde6
Retrograde & Anterograde
  • Retrograde amnesia - Loss of information that was learned before the onset of amnesia
  • Anterograde amnesia - inability to learn new information after the onset of amnesia
  • Both can occur in the same patient and commonly do
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

Causes of Amnesia
brain regions associated with human amnesia
Brain regions associated with human amnesia
  • Diencephalic amnesia - damage to the medial thalamus and mamillary nuclei
  • Medial temporal lobe amnesia - damage to the hippocampal formation, uncus, amygdala, and surrounding cortical areas
brain regions associated with human amnesia11
Brain regions associated with human amnesia
  • Diencephalic amnesia - damage to the medial thalamus and mamillary nuclei
  • Medial temporal lobe amnesia - damage to the hippocampal formation, uncus, amygdala, and surrounding cortical areas
diencephalic amnesia
Diencephalic Amnesia
  • Damage to the medial thalamus and/or mamillary bodies
    • stroke
  • Korsakoff’s syndrome
    • Caused by thiamine deficiency as a result of chronic alcoholism
korsakoff s symptoms
Korsakoff’s symptoms
  • Anterograde amnesia
  • Retrograde amnesia
    • Covers most of the adult life
  • Lack of insight
    • Typically unaware of memory problems
  • Confabulation
    • Patient makes up stories to fill in the past
medial temporal lobe amnesia
Medial Temporal lobe amnesia
  • Hippocampus is most important site of damage
case h m
Case H.M.
  • Epileptic patient
  • Had medial temporal lobes removed to stop seizures
  • Seizures were reduced but H.M. became severely amnesiac.
case h m16
Case H.M.
  • His intelligence is above normal
    • IQ = 112
  • Performs normally on all tests of short-term memory
  • Selective long-term memory impairment
case h m17
Case H.M.

Control brain H.M.

case h m18
Case H.M.
  • Memory impairment for recent events
    • spans the 3 years prior to his surgery
  • Capable of recalling childhood memories
  • Anterograde amnesia was initially thought to be global (all types of memory)
  • later discovered that certain types of learning are intact
case h m19
Case H.M.
  • Grave memory impairment for recent events
    • spans the 3 years prior to his surgery
  • Capable of recalling childhood memories
  • Anterograde amnesia was initially thought to be global (all types of memory)
  • later discovered that certain types of learning are intact
case h m20
Case H.M.
  • Priming still works
  • H.M. can still form procedural memories
case h m21
Case H.M.
  • The Gollin incomplete picture test
    • subjects asked to identify the object
    • pictures are shown in sequence from least to most clear
    • shown the same images at a later date
    • both amnesiacs and control subjects identify the object at an earlier stage
case h m22
Case H.M.
  • Mirror drawing task.
    • Trace figure while looking in a mirror
    • Control subjects get better at this with repetitive training.
case h m23
Case H.M.
  • Mirror drawing task
    • H.M. improved with repeated training.
    • Procedural memory is intact
    • He cannot recall ever having performed this task before

Day 1 Day 2 Day3

case h m24
Case H.M.
  • Doesn’t remember the death of his father
  • Can’t remember or describe his job
  • Doesn’t remember his examiners
case h m25
Case H.M.
  • According to our memory dichotomies, what type of memory is the medial temporal lobe (especially the hippocampus) responsible for?
case h m27
Case H.M.
  • H.M.s Retrograde amnesia is temporally graded
    • remote memory is spared but recent memory is lost
  • Not all amnesia patients show this pattern
    • V.C., N.A. have extensive retrograde amnesia (flat gradient)
lessons from amnesia
Lessons from amnesia
  • Existence of Multiple memory systems
  • Localization of cognitive functions
slide30
S.
  • “Photographic” extreme memory ability (a mnemonist)
  • Able to recall complex test stimuli
slide31
S.
  • “Photographic” extreme memory ability (a mnemonist)
  • Able to recall complex test stimuli
  • 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
slide32
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 don’t 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