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Hippocampus and Memory I. Case of H.M. - Multiple forms of memory - Memory consolidation

Hippocampus and Memory I. Case of H.M. - Multiple forms of memory - Memory consolidation II. Neural Basis of Memory - Hebbian synapse - Long-term potentiation - NMDA receptor. Hippocampus. Hippocampus: Two key findings 1. Human: anterograde and retrograde

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Hippocampus and Memory I. Case of H.M. - Multiple forms of memory - Memory consolidation

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  1. Hippocampus and Memory I. Case of H.M. - Multiple forms of memory - Memory consolidation II. Neural Basis of Memory - Hebbian synapse - Long-term potentiation - NMDA receptor

  2. Hippocampus

  3. Hippocampus: Two key findings 1. Human: anterograde and retrograde amnesia in H.M. -> Declarative memory theory 2. Rodent: place cells -> Cognitive map theory

  4. Other proposed functions of the hippocampus Emotion (Papez, 1937; Isaacson, 1974) Predictive comparator (Gray, 1982) Configural association (Sutherland & Rudy, 1989) Working memory (Olton, 1976) Context (Hirsh, 1974) Spanning temporal discontiguity (Rawlins, 1985) Recognition of novelty (Gaffan, 1972) Sequence memory (Levy, 1989)

  5. I. Case of H.M.

  6. Anterograde vs. retrograde amnesia Retrograde amnesia Anterograde amnesia Temporal lobectomy H.M. : Almost complete anterograde amnesia following bilateral temporal lobectomy

  7. Multiple forms of memory Mirror drawing and Tower of Hanoi tasks

  8. Taxonomy of long-term memory Long-term memory Declarative memory Procedural memory (Explicit, Knowing what) (Implicit, Knowing how) Episodic memory Semantic memory Skills & habits Simple Nonassociative Priming (remembering events) (knowing facts) classical learning conditioning Neocortex Reflex pathways Hippocampus Striatum Cerebellum Parahippocampal region (musculature) Diencephalon Amygdala (emotional response)

  9. Nonassociative learning: Habituation

  10. Classical (Pavlovian) conditioning Operant (Instrumental) conditioning

  11. Demonstration: Word Priming

  12. D E F E N D

  13. H E L I U M

  14. M O D I F Y

  15. C O N V E Y

  16. S I N K E R

  17. D E F

  18. H E L

  19. M O D

  20. C O N

  21. S I N

  22. DEFEND DEFACE DEFEAT DEFINE DEFECT DEFROST ETC.

  23. Taxonomy of long-term memory Long-term memory Declarative memory Procedural memory (Explicit, Knowing what) (Implicit, Knowing how) Episodic memory Semantic memory Skills & habits Simple Nonassociative Priming (remembering events) (knowing facts) classical learning conditioning Neocortex Reflex pathways Hippocampus Striatum Cerebellum Parahippocampal region (musculature) Diencephalon Amygdala (emotional response)

  24. Memory Consolidation Anterograde vs. retrograde amnesia Retrograde amnesia Anterograde amnesia Temporal lobectomy H.M. : Graded retrograde amnesia following bilateral temporal lobectomy

  25. Head trauma and amnesia

  26. Retrograde amnesia in animal studies

  27. Models of Memory System Sensory input Intermediate memory Long-term memory Sensory input Sensory input Intermediate memory Intermediate memory over time Long-term memory Long-term memory

  28. Why memory consolidation? -Not known. -가설: 모든 정보를 그대로 기억하면 용량문제, 또한 필요없는 기억을 저장하는 효율성 문제가 있음. 이를 피하기 위해 intermediate -> long-term memory system이 발달되었음. -가설: 신경망 연구에 따르면 새로운 정보를 기존 지식체계에 급속히 학습시키면 기존 지식체계가 와해됨. 이를 피하려면 새로운 정보를 서서히 기존 지식체계에 편입해야함. Intermediate memory system은 이를 위해 발달. (꿈은 새로운 정보가 기존지식체계로 전달되는 과정?)

  29. Alzheimer’s disease -Hippocampal formation(특히 entorhinal cortex)이 초기에 손상 -초기에는 새로운 기억의 encoding에 문제. 오래된 기억은 정상. Alzheimer’s Disease Normal

  30. Where is long-term memory stored? -Association cortex에 손상이 있을때, 손상부위에 따라 이미 알고있던 얼굴, 물건, 또는 장소 등에 대한 기억이 손상되는 경우가 보고됨. -Temporal lobe를 전기적으로 자극하면 어떤 사건의 경험과 같은 복잡한 sensation 유발 -> activation of memories? -원숭이 inferotemporal lobe의 뉴런들은 학습에 따라 특정물체에 반응하는 양상이 달라짐 -> indication of memory? -Visual imagery때 visual association cortex가 활성화 됨. -Neocortex도 시냅스 가소성이 보고됨. -이러한 결과를 종합할 때 long-term memory는 association cortex에 저장되는 것으로 보임.

  31. II. Neural basis of memory History: 물질 vs. 회로

  32. Declarative memory (associative memory) (content addressable memory) Hebbian synapse Long-term potentiation NMDA receptor

  33. History: two traditional views in memory research 1) Chain of reactions 2) Flashbulb memory (Insight learning)

  34. Hebbian synapse Reverberation Hebbian synapse

  35. Pattern completion based on Hebbian synapse

  36. Pattern completion (content addressable memory) (associative memory)

  37. Neural network -신경망 연구에 의해 Hebbian synapse가 associative memory를 저장할수 있다고 이론적으로 밝혀짐 (Hopfield, 1984). -이때 신경세포들간의 상호연결이 중요함. -신경계에서는 recurrent collateral에 의해 상호연결됨.

  38. Recurrent collaterals in the cortex

  39. Experimental evidence for functional assembly formation

  40. 동시에 발화한 뉴런들 사이의 연결이 강해짐

  41. Declarative memory (associative memory) (content addressable memory) Hebbian synapse Long-term potentiation NMDA receptor

  42. Long-term potentiation (LTP)

  43. LTP represents Hebbian synapse

  44. Declarative memory (associative memory) (content addressable memory) Hebbian synapse Long-term potentiation NMDA receptor

  45. LTP requires calcium entry through NMDA receptor

  46. Active dendrite (back-propagating action potential)

  47. What change is responsible for synaptic weight enhancement? LTP expression hypotheses 4 1 2 3

  48. LTP & AMPA receptor trafficking Gary Lynch and Michell Baudry THE BIOCHEMISTRY OF MEMORY: A NEW AND SPECIFIC HYPOTHESIS.Science. 1984, 224(4653):1057-63. Robert Malinow and Robert C. Malenka AMPA RECEPTOR TRAFFICKING AND SYNAPTIC PLASTICITY Annu. Rev. Neurosci. 2002, 25:103–26

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