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Dr. Brenda Milner Patient H.M.

Dr. Brenda Milner Patient H.M. Amnesia. Retrograde Amnesia impairment of memory for events before the injury. Anterograde Amnesia impairment of memory for events after injury; that is, an impairment in learning. Memory Systems in the Brain. Memory Systems in the Brain. Patient H.M.

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Dr. Brenda Milner Patient H.M.

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  1. Dr. Brenda Milner Patient H.M.

  2. Amnesia • Retrograde Amnesia impairment of memory for events before the injury • Anterograde Amnesia impairment of memory for events after injury; that is, an impairment in learning

  3. Memory Systems in the Brain

  4. Memory Systems in the Brain

  5. Patient H.M. “Right now I'm wondering, Have I done or said anything amiss? You see, at this moment everything looks unclear to me, but what happened just before? That's what worries me. It's like waking from a dream; I just don't remember.” “Every day is alone in itself, whatever enjoyment I've had, and whatever sorrow I've had.” -- H.M.

  6. Memory Systems in the Brain Medial temporal lobe amnesia • Inability to form new explicit memories (anterograde amnesia) • Good IQ, good implicit learning • Loss of memories from before injury (retrograde amnesia)

  7. Medial temporal (contains hippocampus) lesions and DNMS performance (working memory)

  8. Medial Temporal Lobe Memory System Visual Cortex hippocampus Ventral Stream Entorhinal cortex Inferotemporal Cortex Perirhinal cortex Parahippocampal cortex

  9. Memory Teng & Squire, 1999

  10. Memory Teng & Squire, 1999

  11. Memory Teng & Squire, 1999

  12. Memory • Modal view (eg. Alvarez & Squire, 1994; Eichenbaum & Cohen, 2001; McClelland et al., 1995): • A representation of an event is stored very quickly as a readily induced pattern of LTP in limited-capacity hippocampal circuitry • A very long-lasting representation is built up in slowly changing, very high-capacity neocortical circuitry as result of a lengthy process of repetitive patterned output from hippocampus. • Hippocampal mnemonic specificity identical in retrograde and anterograde directions

  13. Memory • Other view: • There is a period of decreasing fragility of representations, but the process occurs within each network (not between) • Temporal gradients in retrograde amnesia arise because of a probabilistic degradation in a partially damaged network • If the hippocampus is intact, it is used (i.e. retrograde will have less specificity than anterograde)

  14. Memory Teng & Squire, 1999

  15. Memory Teng & Squire, 1999

  16. Memory Teng & Squire, 1999

  17. Memory Fanselow et al

  18. Memory Fanselow et al

  19. Memory Fanselow et al

  20. Memory

  21. Memory

  22. Memory

  23. Memory

  24. SRT Results

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