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Memory & the Medial Temporal Lobe. Lesson 22. Memory. Storage of information perceptions learning personality Information processing approach RAM vs. hard drive Multiple memory stores different characteristics Clive Wearing ~. Multiple Memories. Sensory memory

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memory
Memory
  • Storage of information
    • perceptions
    • learning
    • personality
  • Information processing approach
    • RAM vs. hard drive
  • Multiple memory stores
    • different characteristics
  • Clive Wearing ~
multiple memories
Multiple Memories
  • Sensory memory
    • capacity: large; sensory receptors
    • duration: < 1 sec.
  • Short-term memory (STM)
    • capacity: 7 ± 2 chunks
    • duration: < 1 min.
    • maintenance: rehearsal ~
multiple memories1
Multiple Memories
  • Long-term memory (LTM)
    • capacity: functionally unlimited
    • duration: minutes - years
  • Working memory
    • intermediate to STM & LTM
    • information needed longer than 1 min, but not permanent ~
a model of memory

stimuli

transfer

rehearsal

attention

Sensory

Memory

STM

LTM

retrieval

forgetting

forgetting

forgetting

A Model of Memory
subdivisions of ltm
Subdivisions of LTM

1. Declarative - Explicit

  • Episodic:
    • autobiographical
    • time-tagged, automatic
  • Semantic:
    • generic
    • not time-tagged, effortful ~
subdivisions of ltm1
Subdivisions of LTM

2. Procedural – Implicit

    • non-declarative, unconscious
  • Motor learning
  • Nonassociative Learning
    • modulation of reflexes
  • Associative Learning
    • Classical & Operant Conditioning ~
neural mechanism of stm
Neural Mechanism of STM
  • Donald Hebb
  • Change in neural activity
    • not structural
    • temporary
  • Reverberatory Circuits
    • cortical loops of activity
    • activity persists for short period of time ~
slide9

Reverberating loops

  • Maintains neural activity for a period
neural mechanism of ltm
Neural Mechanism of LTM
  • LTM relatively permanent
    • structural change required
  • Hebbian Synapse
    • use strengthens synaptic efficiency
    • requires simultaneous activity
    • pre- and postsynaptic neurons
    • Long-term potentiation (LTP) ~
where are memories stored
Where are memories stored?
  • Engram
    • physical change representing learning and memory
  • Lashley
    • Mass Action & Equipotentiality
  • Classical Conditioning: Eye-blink
    • lateral interpositus nucleus of cerebellum
  • Memories stored locally
    • in different parts of brain ~
slide12
H.M.
  • Greatest contribution to study of memory
    • can’t remember any of it
    • similar to Clive Wearing
  • Bilateral medial temporal lobectomy
    • to control seizures
    • hippocampus (HC) ~
slide13

Hippocampus

Mid-sagittal View

spared some memory
Spared some memory
  • Personality
  • Intelligence
  • LTM
  • Verbal STM memory OK
  • Motor skills
memory deficits

Trauma

time

Memory Deficits
  • Some retrograde amnesia
    • but many old memories intact
  • Severe anterograde amnesia
    • unable to form new memories ~

Retrograde

Anterograde

evidence of deficits
Evidence of deficits
  • Digit Span + 1
  • Block tapping memory span
  • Delayed-matching-to-sample
    • verbal OK - rehearsal
    • nonverbal impaired – ellipses ~
evidence of spared abilities
Evidence of Spared Abilities
  • Performance improved with practice
    • Procedural memory
    • but no conscious memory of it
  • Mirror Drawing
  • Tower of Hanoi ~
conclusions role of hippocampus
Conclusions: Role of Hippocampus
  • Removal of HC  deficits
  • Memory Storage?
    • STM not in HC
    • LTM not in HC
  • HC transfers info STM  LTM?
    • Declarative memories: YES
    • Procedural: NO
  • H. M. anterograde amnesia for declarative memories ~
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