Types of Memory

Types of Memory

STM and LTM
1. Hebb (1949)
  1. No one mech could acc for all phenomena of learning
  2. STM
    1. events that have just occurred
  3. LTM
    1. events from further back
2. STM stores 7 items without rehearsal
  1. LTM vast capacity
3. STM depends on rehearsal
  1. If reheard, chances of remembering it increases but if interrupted chances decrease
  2. LTM things you haven't thought about in years
4. STM once forgotten it is lost
  1. LTM with hints you can reconstruct something you thought you had forgotten
5. all info enters STM where it consolidates into LTM
  1. if interrupted rehearsal before consolidating, info is lost
Changing Views of Consolidation
1. not all STM memos are temp stored before entering LTM
2. Original idea
  1. brain held onto info in STM until synthesising new proteins to enter LTM
3. Stressful or emotionally exciting experiences increase the secretion of epinephrine and cortisol
  1. small amounts of cortisol activate amygdala and hippocampus
    1. They enhance the storage and consolidation of recent experiences
      1. Amygdala in turn stimulates hippocampus and cerebral cortex
  2. prolonged stress releases more cortisol which impairs memory
4. a memory re awakened by a reminder becomes labile - changeable or vulnerable
  1. if reminder is followed by similar experience it's reconsolidated by process requiring protein synthesis
    1. giving a reminder and then taking drug that blocks protein synthesis substantially weakens the memory
    2. new experiences during the reconsolidating process can modify the memory
Working Memory
1. Baddeley & Hitch
2. delayed response task
  1. requires responding to something that you saw or heard a short while ago
  2. using delay, learner stores representation of stimulus
    1. research points to prefrontal cortex as important location for this storage
  3. during delay, certain cells in prefrontal cortex and parietal cortex increase activity
    1. different cells become active depending on direction the eye movement will need to take
      1. Chafee & Goldman-Rakic (1998)
  4. increase in activity doesn't take form of repeated at ion potentials
    1. cells store extra calcium, increasing their readiness to respond to new signals when the time comes
3. damage to prefrontal cortex impairs performance
  1. deficit can be precise depending on exact location of damage
    1. After damage to spot, monkey might be unable to remember that light had been directly to the left although they can see to the left find
4. older people have impairments of WM due to changes in prefrontal cortex
  1. Studies on ages monkeys find decreases in number neurones and amount input in certain part soy prefrontal cortex
  2. those with intact memory show greater activity than young adults
    1. prefrontal cortex is working harder in older adults to compensate for impairments elsewhere in brain

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	Created by n.c.wetmore about 11 years ago