Transcript Long term memory & Memory errors

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 :
1. Synaptic consolidation
2. Systems consolidation
1
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
2
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
year’s 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
10
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
16
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
•
•
•
•
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
Recent memory :
hippocampus
& cortex
Conflict evidence
• Ryan et al.,2004
• Asaf Gilboa and
coworkers,2004
• Moscovitch et
al.,2005
• Nadel & Moscovitch,
1997
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
presented
year after they were initially
– 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 can’t get it out.
– Most of our failures of memory are failures of
retrieval
– Example : you’ve studied hard for an exam
but can’t come up with the answer when
you’re 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 couldn’t
remember what it was.
• As soon as I got home, I remembered
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Retrieval cues : location
Angela’s 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
1. During learning : created cues for “banana” 
own cues provided in test
2. During learning : saw “banana” and cues created
by someone else  other person’s cues
provided in test
3. Didn’t participate in learning  other person’s
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 Baddeley’s 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 Baddeley’s “diving
experiment” and Grant’s 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
person’s 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 person’s 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 wouldn’t 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 statedependent learning, a person’s 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
1.
2.
3.
4.
5.
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. It’s a good method to pretend that you’re
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) 71
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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Smith’s 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
1.
2.
3.
4.
5.
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
Pavlov’s experiment 1927
• He presented a ringing
stimulus ) to a dog
bell ( the neutral
• 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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90
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 rat’s 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 rat’s 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 rat’s
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 :
1. Immediate presentation of anisomycin 
prevents conditioning
2. Later presentation of anisomycin alone
 has no effect (consolidation occurred)
3. 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
97
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.
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