We are what we remember

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We are what we remember

• Memory systems, Learning, Amnesia, and the Brain

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1 Some History

• Pavlov mainly interested in the nature of
  saliva discovers classical conditioning, and
  suggests that CS ? UCS is created by a link
  across different cortex areas
• Karl Lashley sets out to find engram by trying
  to cut the cortex in different areas to find
  engram
• Finds performance degraded by not destroyed
• Suggests two principles of equipotentiality (all
  parts of cortex contribute) and mass action
  (cortex works as a whole, the more the better)
• Donald Hebb proposes neural circuits analogous to
  circuits in computers

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2 Intelligence is not unitary

• It is now known that Lashley was wrong
• From hero to zero?
• Different kinds of ability rely on different
  brain structures
• There are many different kinds of learning and
  memory
• They can be separately impaired as revealed by
  the study of brain damage and amnesiacs

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3 Working Memory

• Working memory (Alan Baddeley)
• Once called Short Term Memory
• George Millers Magic number seven
• Expanded by chunking
• Donald Hebb modeled as a neural loop
• Baddeley thinks made up of Made up of sensory
  registers and
• Phonological loop (auditory info., especially
  words)
• Visuospatial sketchpad (visual information)
• Central executive, directing attention,
  determining what gets stored (e.g., cocktail
  party phenomenon)

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4 Hebbs reverberating circuits
A group of neurons Excite one another Thus
retaining a Temporary memory.
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5 Long-term Memory 1

• Implicit versus explicit memory
• Implicit effects of experience on behaviour
  even if one doesnt consciously realise that they
  exist
• Explicit material that can be deliberately
  recalled, conscious awareness of memory
• Procedural versus Declarative
• Procedural knowing how closer to Implicit?
• Declarative Knowing that factual knowledge
  that can be verbally expressed
• Recognition memory
• Conscious, but just aware of having seen
  something before
• Scottish tartle large size (Standing)

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6 Long-term Memory 2

• Declarative can be broken into
• Semantic memory factual knowledge about the
  world, usually thought of as an interconnected
  web
• Probably includes number and mathematics
• Episodic memory knowledge about events and
  doings sequences of events milestones in ones
  life
• Other long-term memory
• Spatial memory and visual memory
• Sound and music, and probably the other senses
  too
• Pain not stored accurately in long-term memory
  (relative reduction so giving more pain can
  leave a better memory Kahneman)

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7 Implicit memory (long-term)

• Many varieties
• Priming choice of something (e.g. word) related
  to earlier exposure (affects ease of recall,
  readiness to perceive)
• Mere exposure effect (influence on preference)
• Classical conditioning (seems to occur in the
  cerebellum)
• Operant conditioning (effect of reinforcement can
  be unconscious)
• Some varieties of observational learning
• Slow but powerful pattern finding, difficult to
  make conscious
• Guy Caxtons Hare Brain Tortoise Mind has many
  examples

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8 Some common memory tasks

• Digit-length test (working memory) (grows with
  age)
• Word-list learning (primacy and recency effects)
• Various kinds of conditioning (classical,
  operant)
• Delayed matching/non-matching tasks
  (declarative?)
• Radial maze learning (spatial memory)
• Morris search task (support in murky water)
  (spatial memory)
• Configuration learning tasks
• Procedural learning tasks such as Tower of Hanoi
• Recognition tasks which have you seen before?

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9 Task Pictures
Hidden support in murky water
Star Maze
Morris Search task
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10 Memory consolidation

• Transition from working to long-term memory
  requires consolidation
• Role of rehearsal
• Role of arousal (interest, emotion, importance
  attention) direct injection of cortisol or
  adrenalin enhances memory
• Role of dreaming (seems to be involved in
  consolidation and subsequent improvement of
  memory)
• Depth of processing and meaningful framework
  (having knowledge makes it easier to acquire
  more)
• Prefrontal cortex needed to hold memory during
  periods of delay

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11 Amnesia

• Most commonly affects episodic, much less
  commonly semantic memory very rarely procedural
  memory
• Anterograde loss of memory for events that
  happened after brain damage
• Retrograde loss of memory for events prior to
  brain damage
• Infant Amnesia
• Disease processes Korsakoff and Alzheimers
  disease
• Brain injury, cancer and strokes

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12 The case of H.M.

• Epileptic with seizures in hippocampus which
  was removed surgically
• Anterograde and minor retrograde memory loss
  (episodic memory)
• Working memory unaffected
• Most implicit memory and procedural memory intact
  new skills could be learned (but the process of
  learning forgotten)
• Suggests importance of hippocampus in episodic
  memory

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13 The Mysterious Hippocampus

• Structure buried in temporal lobe, loops round
  Thalamus
• Highly connected to rest of brain, but inputs are
  already highly processed something to do with
  conscious memories? Helps memory consolidation
• Not myelinated in until about three
• Infant amnesia?
• Jacob Nadels theory of the origins of
  neuroses?
• Episodic and declarative memory? But what about
  animals?
• Poor performance on delayed matching task

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14 Hippocampus ctd

• Spatial memory (larger in animals with better
  spatial memory)
• Radial maze task (dont enter wrong entrances,
  but forget which correct entrances they have
  already entered)
• Morris search task forget location of support
• Similar performance in young children, suggesting
  hippocampal immaturity
• Function of hippocampus not fully understood
  some counterintuitive research findings

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15 Korsakoffs syndrome

• Brain damage caused by prolonged thiamine
  (vitamin B1) deficiency
• Thiamine needed to metabolize glucose, the brains
  fuel
• Mostly chronic alcoholics who forget to eat
• Thiamine deficiency causes death or shrinkage of
  neurons throughout brain, but especially in
  hypothalamus and thalamus
• Symptoms similar to those of damage to prefrontal
  cortex
• Apathy, confusion, anterograde and retrograde
  amnesia
• Thiamine treatment helps, but outlook often bleak

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16 Korsakoff ctd

• Implicit memory (priming) unaffected, but
  episodic memory strongly affected
• Difficulty in reasoning about order of events
• Tendency to confabulate guesses at answer then
  accepts guess as if memory
• Confabulation means that rehearsal works better
  than self-testing as learning strategy

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17 Alzheimers Disease

• Degenerative disease of the brain (autopsy for
  certain)
• Starts with minor loss of episodic memory
  (procedural memory is less affected), then
  serious memory loss, confusion
• Progresses to loss of identity, personality
  changes, depression, loss of appetite,
  restlessness, sleeplessness (destruction of
  neural structures controlling sleep and rhythms),
  hallucinations, and delusions
• Sometimes younger than 40 5 of 65-74 year-olds
  50 of people over 85
• Accumulation of amaloid and metal (aluminium)
  deposits in the brain shrinkage and destruction
  of cortex starting with hippocampus
• Plaques tar like structures formed by
  degenerated axons and dendrites are found in the
  brain tangles neuronal bodies

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18 Alzheimers Disease ctd

• The cause is not known, but many theories
• Kalat opts for genetic causes
• Genes on chromosomes 21, 14 and 1 may be
  responsible for producing amaloid proteins which
  accumulate in the brain and cause cortex to
  atrophy
• Downs syndrome always get Alzheimers if they
  survive to middle age
• Thus amaloid proteins a cause, not an effect
• Other possible causes
• Virus, pollutants, autoimmune disease

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19 Alzheimers Disease - treatment

• There are now drugs that can slow down progress
  of Alzheimers
• Insulin seems to help not known why
• Stimulate acetylcholine receptors
• Block amaloid protein production
• Early diagnosis now possible
• Vaccine against amaloid protein a possibility
• Keep brain active less likely in active people