Forming memories in the brain : Process of consolidation

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Forming memories in the brain Process of
consolidation

• Consolidation transforms new memories from a
  fragile state to a more permanent state
• Levels of reorganization in nervous system
• Synaptic consolidation
• Systems consolidation

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Synaptic consolidation

• Occurs at synapses
• Happens rapidly
• Over a period of minutes
• Discovered molecular processes involved in
  synthesizing the proteins that result in
  structural change at the synapse

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Systems consolidation

• Many brain regions
• Gradual reorganization of cortical circuits
• Takes place on a longer time scale, lasting
  weeks, months, or even years
• Importance of hippocampus in consolidation
• H.M. lost his ability to form new memories after
  his hippocampus was removed

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Chapter summery 17

• Consolidation transforms new memories into a
  state in which they are more resistant to
  disruption.
• Synaptic consolidation occurs at synapses and is
  rapid.
• Systems consolidation involves the reorganization
  of cortical circuits and is slower

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H.M.

• Anterograde amnesia
• Removal of H.M.s hippocampus made it impossible
  for him to form new memories
• Retrograde amnesia (partially)
• Amnesia extended back for about 10-15 years prior
  to his operation
• He could remember events that occurred before then

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Graded amnesia

• H.M. could remember events from his childhood,
  but apparently not with as much clarity and
  detail as a person without brain damage
• Graded amnesia amnesia is most severe for
  events that occurred just prior to the injury and
  becomes less severe for earlier, more remote
  events

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Forming memories in the brain Fragility of new
memories

• Graded amnesia (retrograde amnesia)
• Memory for recent events is more fragile than
  memory for remote events

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Forming memories in the brain Fragility of new
memories

• Consolidation
• Transforms new memories from a fragile state, in
  which they can be disrupted, to a more permanent
  state, in which they are resistant to disruption
• A consolidation process must occur before
  memories become resistant to being disrupted

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Hippocampus consolidation

• Memory retrieval depends on the hippocampus
  during consolidation
• Once consolidation is complete
• Retrieval no longer depends on the hippocampus
• Example Graded amnesia after hippocampectomy

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• Your memory for last new years Eve could include
  sights, sounds, smells, emotions you were feeling
  and thoughts you were thinking at the stroke of
  midnight
• Experience results in activity of the different
  cortical areas
• No connection in the cortex

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Standard model of consolidation

• Incoming information activates a number of areas
  in the cortex.
• Activation is distributed across the cortex
  because memories typically involve many sensory
  and cognitive areas.
• Cortex communicates with hippocampus

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Reactivation

• Hippocampus replays the neural activity
  associated with a memory
• Results in the formation of connections between
  the cortical areas

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Standard model of consolidation

• Reactivation process occurs during sleep or
  during periods of relaxed wakefulness
• Reactivation process can be enhanced if a
  consciously rehearses a memory

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Standard model of consolidation

• Consolidation occurs during sleep
• Peigneux et al.,2004
• Walker Stickgold, 2004
• Finding that memory for learning is enhanced when
  the learning is immediately followed by a period
  of sleep

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Standard model of consolidation

• cortical connections become strong enough
• the different sites in the cortex become directly
  linked
• hippocampus is no longer necessary

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Standard model of consolidation
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Chapter summery 18.1

• The standard model of consolidation proposes that
  
• during consolidation
• Memory retrieval depends on the hippocampus
• after consolidation is complete
• Memory retrieval involves the cortex
• Hippocampus is no longer involved

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Standard model of consolidation

• Retrieval of recent memories depends on the
  hippocampus, and cortical connections have not
  yet formed
• (a) For retrieval of recent memories, hippocampal
  activation is high and cortical activation is low

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Standard model of consolidation

• Once consolidation has occurred, cortical
  connections have formed, and the hippocampus is
  no longer needed.
• (b) For retrieval of remote memories, cortical
  activation is high, and there is no hippocampal
  activation.

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Standard model of consolidation

• Recent memory hippocampus cortex
• Remote memory cortex only

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Medial temporal lobe semantic M
Recently learned memories cause activity in the
MTL
MTL do not activated for remote (semantic)
memories.
Haist 2001 , Wiltgen 2004
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Mental time travel (episodic M) MTL
episodic memory

• Ryan et al.,2001
• Participants engage in mental time travel
• fMRI study activity in hippocampus
• MTL is activated both when recent episodic
  memories and remote episodic memories are
  retrieved

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Hippocampus is activated during retrieval of both
recent and remote memories
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Asaf Gilboa and coworkers 2004

• Showing photographs of themselves engaging in
  various activities that were taken at times
  ranging from very recently, to when they were 5
  years old
• Results hippocampus was activated during
  retrieval of both recent and remote memories.

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Moscovitch Nadel 1997

• Experiments that demonstrate MTL and HC
  activation when retrieving remote episodic
  memories
• Support the idea that the hippocampus and MTL are
  always important when accessing the details of
  episodic memories

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Peter Bayley and coworkers 2005

• Describe patients with damage to the MTL who were
  still able to remember the details of remote
  episodic memories
• Results fits the standard model

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Standard model of consolidation

• Support evidence
• Haist et al.,2001
• Wiltgen et al.,2004
• Peter Bayley and coworkers 2005

• Conflict evidence
• Ryan et al.,2004
• Asaf Gilboa and coworkers,2004
• Moscovitch et al.,2005
• Nadel Moscovitch, 1997

Recent memory hippocampus cortex Remote
memory cortex only
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Chapter summery 18.2

• There is evidence supporting the standard model
  of consolidation,
• and also evidence supporting the idea that
  retrieval of episodic memories always involves
  the hippocampus.

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Emotional memory

• More emotionally events seem to be remembered
  more easily and vividly than less emotionally
  events
• Beginning or ending relationships
• Arousing words / Neutral words
• Events experienced by many people simultaneously
  tsunami , 9/11 terrorist attack

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Memory for emotional stimuli

• Kevin Lavin and Elizabeth Phelps 1998
• Emotionally charged events are easier to remember
• Tested participants ability to recall
• Arousing words profanity sexually explicit
  words
• Neutral words street , store
• They can recall immediately after they were
  presented
• Results better memory for arousing words

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Memory for emotional stimuli

• Florin Dolcos and coworkers 2005
• Tested participants ability to recognize
  emotional and neutral pictures
• Memory test 1 year after they were initially
  presented
• Results better memory for the emotional pictures

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Memory for emotional stimuli
(a) Immediately after reading a word (b) 1 years
after viewing the pictures
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Memory for emotional stimuli

• Emotional memory / Amydala
• Brain imaging fMRI measured by Dolcos
• Amygdala activity was higher for the emotional
  words

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Memory for emotional stimuli

• Emotional memory / Amygdala
• Neuropsychological study
• Viewed a slide show about a boy and his mother in
  which a boy is injured halfway through the show
• Participants without brain damage
• Enhanced memory for emotional part of story
• B.P. damaged to amygdala
• Not enhanced

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Memory for emotional stimuli

• Amygdala
• Emotion improves memory
• Emotion enhance the process of consolidation

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Chapter summery 19

• Memory for emotional stimuli is generally
  enhanced compared to memory for neutral stimuli.
• The results of brain scanning and
  neuropsychological experiments indicate that the
  amygdala is involved in emotional memory.

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How do we retrieve information from LTM ?

• Retrieval failure occur when the information is
  in there , but we cant get it out.
• Most of our failures of memory are failures of
  retrieval
• Example youve studied hard for an exam but
  cant come up with the answer when youre taking
  the exam, only to remember it later when the exam
  is over.

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Retrieval cues

• Cues that help us remember information stored in
  our memory
• Returning to a particular place stimulated
  memories associated with that place
• Location can serve as a retrieval cue

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Retrieval cues location

• While I was in my office at home ,I had made a
  mental note to be sure to take the DVD on amnesia
  to school for my cognitive psychology class
• A short while later, as I was leaving the house,
  I had a nagging feeling that I was forgetting
  something, but I couldnt remember what it was.
• As soon as I got home, I remembered

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Retrieval cues location

• Angelas experience
• When I was 8 years old, both of my grandparents
  passed away. Their house was sold, and that
  chapter of my life was closed. Since then I can
  remember general things about being there as a
  child, but not the details.
• One day I decided to go for a drive. I went to my
  grandparents old house and I pulled around to
  the alley and parked. As I sat there and stared
  at the house, the most amazing thing happened. I
  experienced a vivid recollection.
• All of a sudden, I was 8 years old again. I could
  see myself in the backyard, learning to ride a
  bike for the first time. I could see the inside
  of the house. I remembered exactly what every
  detail looked like. I could even remember the
  distinct smell. So many times I tried to remember
  these things, but never so vividly did I remember
  such detail.

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Retrieval cues

• That are provided by returning to the location
  where memories were initially formed.
• Hearing the particular song can bring back
  memories for events you might not thought about
  for years
• A musty smell like the stairwell of my
  grandparents house that used to climb

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Cued recall

• Endel Tulving and Zena Pearlstone 1966
• Presented participants with a list of words to
  remember
• Free-recall group
• Pigeon, sparrow, chair, dresser, engineer, lawyer
• Cued-recall group
• Birds Pigeon, sparrow
• Furniture chair, dresser
• Professions engineer, lawyer

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Cued recall

• Endel Tulving and Zena Pearlstone 1966
• For the memory test,
• Participants in the free-recall group were asked
  to write down as many as possible.
• Participants in the cued-recall group were also
  asked to recall the words, but were provided with
  the names of the categories birds , furniture,
  professions

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Endel Tulving and Zena Pearlstone 1966
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Cued recall

• Endel Tulving and Zena Pearlstone 1966
• Conclusion the retrieval cues aid memory
• Free-recall gr. Recall 40
• Cued-recall gr. Recall 75

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Power of retrieval cues

• Timo Mantyla 1986
• He presented his participants with a list of 600
  nouns,
• such as banana , freedom , tree
• During learning, the participants were told to
  write down three words they associated with each
  noun
• Banana yellow , bunches , edible

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Power of retrieval cues

• Timo Mantyla 1986
• When the participants took a surprise memory
  test,
• They were presented with the three words they had
  created and were asked to produce the original
  word,
• They were able to remember 90 of the 600 words

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Power of retrieval cues

• Timo Mantyla 1986
• Compared to another groups
• During learning created cues for banana ? own
  cues provided in test
• During learning saw banana and cues created
  by someone else ? other persons cues provided in
  test
• Didnt participate in learning ? other persons
  cues provided in test

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Power of retrieval cues

• Timo Mantyla 1986

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Power of retrieval cues

• Timo Mantyla 1986
• Conclusions
• Retrieval cues ( the 3 words ) provide extremely
  effective information for retrieving memories,
• but that the retrieval cues were more effective
  when they were created by the person whose memory
  was being tested

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Chapter summery 20

• Retrieving LTM is aided by retrieval cues.
• This has been determined by cues- recall
  experiments and experiments and experiments in
  which participants created retrieval cues that
  later helped them retrieve memories.

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Encoding specificity

• Memory is better when a cue that was associated
  with an event is reinstated when the event is
  to be remembered
• Encoding
• Retrieval

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Encoding specificity

• D.R. Godden and Alan Baddeleys 1975
• diving experiment
• On land studying a list of words group
• Underwater studying a list of words group
• Each ½ of both groups were tested for recall on
  land
• Each ½ of both groups were tested for recall
  underwater

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diving experiment
The best recall occurred when encoding and
retrieval occurred in the same environment
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Encoding specificity

• Harry Grant and coworkers 1998
• Studying experiment
• Participants read an article on psycho immunology
  while wearing headphones.
• Silent condition group
• Noisy condition group
• Half of each short-answer test on the article
  under silent condition
• Half of each short-answer test on the article
  under noisy condition

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Studying experiment
Participants did better when the testing
condition matched the study condition
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Chapter summery 21

• The principle of encoding specificity states that
  we learn information along with its context.
• Godden and Baddeleys diving experiment and
  Grants studying experiment illustrate the
  effectiveness of encoding and retrieving
  information under the same conditions

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State-Dependent learning

• Internal state mood or state of awareness
• Learning is associated with a particular internal
  state
• Principle memory will be better when a persons
  state during retrieval matches his or her
  internal state during encoding

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State-Dependent learning

• Eric Eich and Janet Metcalfe 1989
• Memory is better when a persons mood during
  retrieval matches his or her mood during
  encoding.
• Asking participants to think positive thoughts
  while listening to merry music or depressing
  thoughts while listening to melancholic music
• Participants rated their mood while listening

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State-Dependent learning

• Eric Eich and Janet Metcalfe 1989
• When mood rating reach very pleasant or very
  unpleasant
• Encoding part of the experiment began
• Participants studied lists of words while in
  their positive or negative mood

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State-Dependent learning

• Eric Eich and Janet Metcalfe 1989
• After the study session ended
• Participants were told to return in 2 days
• The sad group stayed in the lab a little longer
• Snacking on cookies and chatting with the
  experimenter while happy music played in the
  background
• So they wouldnt leave the laboratory in a bad
  mood

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State-Dependent learning

• Eric Eich and Janet Metcalfe 1989
• 2 days later
• Participants returned
• The same procedure was used to put them in a
  positive or negative mood.
• When they reach the mood
• They were given a memory test for the words they
  had studied 2 days earlier

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State-Dependent learning
The best recall occurred when encoding and
retrieval matched in same mood
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Chapter summery 22

• According to the principle of state-dependent
  learning, a persons memory will be better when
  his or her internal state during retrieval
  matches the state during encoding.
• Eich s mood experiment supports this idea.

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What memory research tells us about studying ?

• Ways of improving learning and memory
• Elaborate and generate
• Organize
• Associate
• Take breaks
• Match learning and testing conditions

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Elaborate and Generate

• Elaboration
• The step that transfer the material you are
  reading into LTM
• Maintenance rehearsal read and reread
• Elaborative rehearsal better transfer to LTM

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Elaborate and Generate

• Research has shown that
• students who read a text with the idea of making
  up questions did as well on an exam as students
  who read a text with the idea of answering
  questions later ,
• and both groups did better than a group who did
  not create or answer questions

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Elaborate and Generate

• Study technique method of talking out loud
• Mahya Tavakkoli s method
• My study technique is to talk out loud and
  explain everything that I know. Sometimes when
  you read the material, you think Yeah! I know
  this! and move on.
• But when you get to the exam, you get struck!
  This is because the material is not in front of
  you.
• So by explaining everything out loud, it makes
  much more sense. Its a good method to pretend
  that youre the professor trying to teach a class
  of 500 students.

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Elaborate and Generate

• S.W. Peterson 1992
• 82 of students highlight
• Most of them do so while they are reading the
  material for the first time
• Compared comprehension of both groups ? no
  difference between the performance of both groups
  when they were tested on the material

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Elaborate and Generate

• Elaborative processing generation effect
• Making up question
• Answering question
• Recheck correction of the answer to get feedback
• Mahya s method of pretending you are the
  professor
• Beware of highlighting (automatic behaviour)

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Organize

• Memory is better when the material is organized.
• Organization
• creates a framework that helps relate some
  information to other information
• Making trees
• Image
• Chunking
• makes the material more meaningful
• Reduce the load on your memory

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Associate

• Elaborative processing is associating what you
  are learning to what you already know
• Prior learning creates a structure on which to
  hang new information
• Creating imaging that link two things

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Take breaks

• Study in a number of shorter sessions rather than
  trying to learn everything at once
• Memory is better
• when studying the material is broken into a
  number of short sessions with breaks in between
• than when studying occurs in one long session

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Take breaks

• The advantage for short study sessions is called
  Distributed versus massed practice effect
• It is difficult to maintain close attention to
  material throughout a long study session
• Studying after a break gives better feedback
  about what you actually know.
• Consolidation is enhanced during sleep

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Sleep effect

• Helps consolidation
• Restorative effect
• Improves ability to concentrate and pay attention

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Match learning and testing conditions

• Memory should be better when study (encoding) and
  testing (retrieval) conditions match as closely
  as possible.
• Encoding specificity
• State-dependence learning

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Smiths result

• Research has shown that people remember material
  better
• when they have learned it in a number of
  different locations,
• compared to spending the same amount of time
  studying in one location

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Match learning and testing conditions
Making up questions about the material helps
encoding Answering the questions, which involves
retrieval, not only provides feedback about how
well you know the material but helps achieve
better encoding as well
This strengthened encoding then increases the
likelihood that retrieval will be successful
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Chapter summery 23

• Five memory principles that can be applied to
  studying are
• Elaborate and generate
• Organize
• Associate
• Take breaks
• Match learning and test conditions

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Are memories ever Permanent ?

• Memory is initially fragile, so a disrupting
  event that occurs shortly after a memory is
  formed can disrupt formation of memory
• Once consolidation has occurred, then the same
  disrupting event cannot affect the memory

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Conditioning

• Conditioning
• procedure in which pairing a neutral stimulus
  with a stimulus that elicits a response
• causes the neutral stimulus to elicit that
  response

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Conditioning

• Pavlovs experiment 1927
• He presented a ringing bell ( the neutral
  stimulus ) to a dog
• Followed by presentation of food ( which causes
  the dog to salivate )
• This pairing eventually caused the dog to
  salivate when it heard the bell

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Conditioning

• Stimulus (food) ? response (saliva)
• Stimulus neutral stimulus (ringing bell) ?
  response
• Neutral stimulus ? response

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Fear conditioning

• Stimulus (unpleasant) ? response (avoid)
• Shock ? freeze
• Stimulus (shock) neutral stimuli (tone) ?
  response (freeze)
• Neutral stimulus (tone) ? response (freeze)

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Fear conditioning

• The rat hears a tone
• The rat receives a shock to its foot
• The shock causes the rat to freeze in place
• Pairing tone shock
• The rat tested later
• Neutral tone causes the fear response of freezing

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Fear conditioning
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Fear conditioning

• Karim Nader s experiments
• How injection of the chemical anisomycin would
  affect fear conditioning
• Anisomycin
• ATB that inhibits protein synthesis,
• which causes the structural changes at the
  synapse that are responsible for the formation of
  new memories

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Effect on fear conditioning of injecting
anisomycin

• Condition 1 inject before consolidation
• Condition 2 inject after consolidation
• Condition 3 inject during reactivation

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1 Immediate presentation of anisomycin

• Day1 inject anisomycin Initial condition
  (tone shock) ? fear response in rat (freeze)
• Anisomycin disrupts protein synthesis before
  consolidation occur
• Day3 tone condition ? no rats memory for
  shock-tone pairing ? rat does not freeze

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2 Later presentation of anisomycin alone

• Day1 shock-tone pairing condition ? fear
  response (freeze) ? consolidation rat learn to
  fear tone
• Day2 inject anisomycin 24 hours after that
• No disruption of rats memory
• Consolidation has occurred
• Day3 tone ? rat freeze

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3 Later presentation of anisomycin with the tone

• Day1 shock-tone pairing condition ? fear
  response (freeze) ? consolidation rat learn to
  fear tone
• Day2 tone ? rat freeze ? reactivation inject
  anisomycin ? eliminates the rats memory
• Day3 tone ? rat has no memory ? rat does not
  freeze

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Karim Nader s experiments

• Karim Nader injected the anisomycin under 3
  different conditions
• Immediate presentation of anisomycin ? prevents
  conditioning
• Later presentation of anisomycin alone ? has no
  effect (consolidation occurred)
• Later presentation of anisomycin with the tone ?
  eliminates conditioning

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Reconsolidation

• Learning ? consolidation ? learning ?
  reactivation reconsolidation ? memory
• 1 learning // no consolidation
• 2 learning ? consolidation ? memory
• 3 learning ? consolidation ? learning ?
  reactivation // no reconsolidation ? eliminates
  memory

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Updating memory

• Animal returns to the location of a food source
• Reactivates the original memory
• Animal finds that the food has been moved to a
  new nearby location
• New information updates the memory
• Updated memory is then reconsolidation

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Updating memory

• Reconsolidation reactivation occur when
  retrieved , provide an opportunity for
  reinforcing or updating memories
• Memory becomes to being changed or disrupted
  every time it is retrieved
• Memory becomes a more dynamic and adaptable
  process

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Chapter summery 24

• Recent research on memory, based largely on fear
  conditioning in rats, indicates that memories can
  become susceptible to disruption when they are
  reactivated by retrieval.
• After reactivation these memories must be
  reconsolidated.
• This process may be a mechanism for refining and
  updating memories.