Amnesia

• Loss of memory ability - usually due to lesion or surgical removal of various parts of the brain

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• Lack of Sleep!

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

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

RetrogradeAmnesia

AnterogradeAmnesia

Amnesia

Amnesia

• Short-term and sensory memory are typically functional

Korsakoff’s Syndrome

The Lost Mariner - What happened to Jimmie? What was his life like?

Korsakoff’s Syndrome (The Lost Mariner)

• Lesions to Medial Thalamus– Results from chronic alcoholism and

consequent thiamine deficiency

Korsakoff’s Syndrome (The Lost Mariner)

• Lesions to Medial Thalamus– Results from chronic alcoholism and

consequent thiamine deficiency– Severe anterograde amnesia

Korsakoff’s 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

Korsakoff’s 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

Korsakoff’s 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

H. M.

• Patient H. M. - suffered from extreme epilepsy

H. M.

• Patient H. M. - bilateral resection of medial temporal lobes (containing hippocampus)– William Beecher Scoville and Brenda

Milner - late 1950’s

H. M.

• Patient H. M. - bilateral resection of medial temporal lobes (containing hippocampus)– William Beecher Scoville and Brenda

Milner - late 1950’s – Severe anterograde amnesia

H. M.

• Patient H. M. - bilateral resection of medial temporal lobes (containing hippocampus)– William Beecher Scoville and Brenda

Milner - late 1950’s – Severe anterograde amnesia– Retrograde amnesia for 1 - 3 years before

surgery

H. M.

H. M.

• Some aspects of memory were spared (at least to some extent)

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

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

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) !

Hypermnesia - S.

• “Photographic” extreme memory ability (a mnemonist)

Hypermnesia - S.

• “Photographic” extreme memory ability (a mnemonist)

• Able to recall complex test stimuli

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

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

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 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

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