2019-04-15 12:33:12

Today's topics

  • Biological basis of learning & memory
  • Quiz 4
  • Review Exam 3

Coming up

  • (Fun!) In-class lab next Tuesday
  • Review for Exam 4 next Thursday
  • Exam 4, Thursday 5/2, 4:40-6:30 pm in 112 Buckhout

Memory systems in the brain

Review from last time

  • Learning and memory involve changes in neural firing, circuitry
  • Hebbian learning a type of associative learning
  • NMDA receptor as coincidence detector
    • Molecular basis of one form of long-term potentiation (LTP)
  • Different types of information stored in different brain systems

Disorders of memory

Patient HM (Henry G. Molaison)

  • Intractable/untreatable epilepsy
  • Bilateral resection of medial temporal lobe (1953)
  • Epilepsy now treatable
  • But, memory impaired
  • Lived until 2008

Brenda Milner tells the story

HM's surgery

Amnesia

  • Acquired loss of memory
  • ≠ normal forgetting
  • Note: computers don't forget

HM's amnesia

  • Retrograde amnesia
    • Can’t remember 10 yrs before operation
    • Distant past better than more recent
  • Severe, global anterograde amnesia
    • Impaired learning of new facts, events, people
  • But, skills (mirror learning) intact

Types of amnesia

  • Retrograde ('backwards' in time)
    • Damage to information acquired pre-injury
    • Temporally graded
  • Anterograde ('forward' in time)
    • Damage to information acquired/experienced post-injury

What it's like

Every day is alone in itself, whatever enjoyment I’ve had, and whatever sorrow I’ve had…Right now, I’m wondering, have I done or said anything amiss? You see at this moment, everything looks clear to me, but what happened just before? That’s what worries me. It’s like waking from a dream. I just don’t remember.

What it's like

Other causes of amnesia

  • Disease
    • Alzheimer’s, herpes virus
  • Korsakoff’s syndrome
    • Result of severe alcoholism
    • Impairs medial thalamus & mammillary bodies

Patient NA

  • Fencing accident
  • Damage to medial thalamus
  • Anterograde + graded retrograde amnesia
  • Are thalamus & medial temporal region connected?

Patient NA

Spared skills in amnesia

  • Skill-learning
  • Mirror-reading, writing
  • Short-term memory
  • “Cognitive” skills
  • Priming

What does amnesia tell us?

  • Long-term memory for facts, events, people
  • ≠ Short-term memory
  • ≠ Long-term memory for “skills”
  • Separate memory systems in the brain?

Memory systems in the brain

References

Squire, Larry R. 2004. “Memory Systems of the Brain: A Brief History and Current Perspective.” Neurobiology of Learning and Memory, Multiple Memory Systems, 82 (3): 171–77. doi:10.1016/j.nlm.2004.06.005.