Amnesia What is it?

1. AmnesiaWhat 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 • Korsakoff’s syndrome • Caused by thiamine deficiency as a result of chronic alcoholism

15. Korsakoff’s Syndrome The Lost Mariner - What happened to Jimmie? What was his life like?

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

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

18. 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

19. 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

20. 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

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 1950’s

24. 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

25. 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

26. H. M.

27. 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 • 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 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

40. Amnesia What pattern of result can be seen across these patient’s 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. Have a good Week