Transcript memory failure

Memory Mechanisms Two
Retrospective and Prospective Coding
• As rats move around on a radial maze to get food they need to
remember the visited arms
– they use retrospective coding for the first few arms
– then use prospective for the remaining arms
• Retrospective memory – coding past event - places visited
• Prospective memory – coding future plan of action - places to be
visited.
• Using memory to think about past experiences and think about
future events is referred to as mental time travel
– We will cover more on this at the beginning of the next chapter
– So rats may be able to think about the past and/or the future
– Although this is a controversial proposal because nonhuman animals may not
have the same cognitive processes as humans
Retrospective and Prospective Coding
• Feeney, Roberts and Sherry, 2011
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experiments on black-capped chickadees foraging behavior
given access to sunflower seeds before given access to mealworms
chickadees like the mealworms a lot better than the sunflower seeds
when trained with a delay between sunflower seeds and mealworms
• chickadees learn to hold back on eating the sunflower seeds
• so that they would have more room for the mealworms
– see figure 11.9
– Prospective memory in the foraging behavior of birds
FIGURE 11.9
Mean number of sunflower seeds eaten by chickadees that did not get more preferred mealworms later
(control group) and chickadees that got mealworms 30 minutes later (experimental group).
The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.
Retrospective and Prospective Coding
• Beran (2012) matching to sample procedure with monkeys
– monkeys trained to use a joystick to move a cursor on a computer screen
– presented with a sample stimulus surrounded by four possible choices on the
computer screen
– see figure 11.10
– monkeys had to move the cursor to the sample first and then move the
cursor to the match
– the four choices disappeared as soon as the monkey started to move the
cursor
– so they had to remember their choice before making the movement
• Many of the monkeys became very skilled at this task
– Even when they had to do a filler activity after moving the cursor to the
sample
FIGURE 11.10
Matching-to-sample task used in a test of prospective coding with monkeys. The sample stimulus
appeared in the center of the display, and the choice alternatives appeared on the corners (left panel).
The monkeys had to move the cursor to the sample first and then to the location of the correct corner.
However, as soon as they moved the cursor, the choice alternatives were masked (right panel). (Based
on Baran et al. 2012a).
The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.
Retention and the Problem of Rehearsal
• Retention is the second phase of memory
– Rehearsal is repetition of information in order to keep it in working memory
• repeat recently-learned phone number (867-5309); repeat someone’s name, etc.
– In some studies with human subjects recall was better when expecting a
recall task indicating control over working memory content
• Working memory that will not be needed again is lost
– Forget a phone number after using it
– Could be a strategic process, benefitting memory by reducing interference
• Directed Forgetting
– Other studies with human subjects demonstrated that working memory can
be modified by instructions indicating that something should not be
remembered
• When given a list to memorize
– some of the items were marked with remember cues
– other items were marked with forget cues
– Example of directed forgetting procedure for humans
Retention and the Problem of Rehearsal
• Milmine 2008
• Directed forgetting procedure using (DMTS) with pigeons
– "Remember" sample stimulus (light), then Remember cue (R) tone then the
delayed matching test given
– "Forget" : sample stimulus (light), then Forgetting cue (F) tone then nothing
– "Free-reward" trials: sample followed by combination F-r cue
– Occasionally “Forget probe” trials with delayed matching test after the F-cue
– Occasionally "Free-reward probe" trials with delayed matching test after the
combination F-r cue
– See Figure 11.11
• Results
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Figure 11.12
better recall on R-cue trials then F-cue trials
Also good recall on free-reward trials
Evidence of ‘directed forgetting’ on F probe trials
Suggests that working memory is an active process, susceptible to
interference during the retention phase
The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.
FIGURE 11.12
Accuracy in delayed matching to sample in pigeons EZ2 and T19 on R-cue, F-cue, and free-reward
trials. (Based on “Neural Correlates of Directed Forgetting in the Avian Prefrontal Cortex,” by M. Milmine,
A. Watanabe, and M. Colombo, 2008, Behavioral Neuroscience, 122, 199–209.)
The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.
Retrieval
• The third phase of memory is retrieval of information from longterm stores
• Once information has been coded and retained, must be able to
recover it to help guide behavior
• Most memory failure is because of retrieval failure not loss of
information
• Retrieval is triggered by retrieval cues so better cues makes for
better retrieval
Retrieval cues and Memory for Instrumental
Behavior in Human Infants
• Retrieval cues are parts of the information processed during
acquisition
– help form a connection with the entire memory
– they can be specific stimuli such as a sound or odor but can also be general
context information
• Retrieval of memories is facilitated when the context cues used for
recall are identical to those at encoding
• Borovsky & Rovee-Collier (1990)
• Retrieval of instrumental learning examined in 6-month-old infants
– Operant conditioning of a leg kick reinforced by movement of a mobile
– Contextual stimulus – crib liner varied between training and test
– 4 groups
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Same cloth liner (group Same)
New cloth liner (group Diff)
Familiar cloth liner not present at training (group Diff-Fam)
No liner (Group None-Fam)
– Best retention for Group Same see Figure 11.13
FIGURE 11.13
Retention scores of six-month-old infants in a test of instrumental conditioning. Group Same was tested
in a playpen with the same cloth liner that had been present during conditioning. Group Diff was tested
with a new cloth liner. Group Diff-Fam was tested with a familiar cloth liner that was different from the
one in the playpen during conditioning. Group None-Fam was tested without a cloth liner but in a familiar
playpen in a familiar room. (Based on “Contextual Constraints on Memory Retrieval at Six Months” by D.
Borovsky and C. Rovee-Collier, 1990, Child Development, 61, pp. 1569–1583.)
The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.
The Generality of Retrieval Cues
• Presentation of some aspect of the original learning situation during
retention interval
– Many instances of memory loss can be alleviated by reminder treatments at
the time of testing
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Exposure to contextual cues (Renewal)
Exposure to the US (Reinstatement)
Exposure to the CS+
Exposure to the CS-
• Retrieval cues and memory priming
– The retrieval cue is presented at the end of a retention interval
– Suss, Gaylord and Fagan 2012
• Three-month-old babies kicked their legs to move a mobile In the presence of an
odor “modulator” cue
• babies were given a priming treatment
– They were returned to the crib and saw the mobile being moved
– Either with same odor, different odor or no odor
• Priming with the same odor was the best reminder
• see figure 11. 14
FIGURE 11.14
Retention of an instrumental response in three-month-old babies tested seven days after original
training. One day before the retention test, independent groups received a priming treatment in the
presence of either the same or a different odor than what was present during original training. Control
groups (shown on the right) received either no odor during priming or did not get the priming procedure.
Only group “Same Odor” showed significant retention, as indicated by the asterisk. (Based on Suss,
Gaylord, and Fagen, 2012; Figure 1, page 582. Elsevier)
The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.
Forgetting and Sources of Memory Failure
• Forgetting is failure of memory
– Not just information loss with passage of time
– There are several explanations for memory failure
• information was not completely stored in memory because of poor acquisition
or coding
– information was not processed deep enough to be stored as long-term
memory
– interference is an example of this problem
• failure to retrieve information in memory usually because of inadequate retrieval
cues
• information in memory is reorganized when new information is combined with
old information
• damage to the neural circuits, from disease or trauma, that are processing or
storing the information
Proactive and Retroactive Interference
• Interference is most problematic for similar information such as
names of people
• Proactive
– earlier information interfering with a later target information (forward acting)
– for example meeting new people at a party, Bob, Alice, Larry, Mary, makes
Mary difficult to remember because of previous names.
– Difficult to rehearse "Mary" because working memory is full of other names
• Retroactive
– later information interfering with earlier target information (backward
acting)
– for example meeting new people at a party, Bob, Alice, Larry, Mary, makes
Bob difficult to remember because of later names.
– Usually memory loss due to disruption of rehearsal, can not rehearse "Bob"
will getting new names
Retrograde Amnesia
• Head injury “concussion” can produce memory failure
– For example Trevor Rees-Jones after the crash that killed Princess Diana
• not being able to recall information from just before the accident
• but can remember things from earlier in the day
– Temporal gradient of memory loss going back in time “retrograde” from the
point of injury with more severe loss the closer to the time of injury
• Retrograde amnesia can occur from a number of causes
– Such as anesthesia, seizure, hypothermia, Electroconvulsive shock (ECS),
drugs that inhibit protein synthesis
– Hypothermia and Electroconvulsive shock (ECS) have been used to induce
amnesia in non-human animal models of retrograde amnesia
– closer the time between the end of the conditioning trial and the delivery of
hypothermia or ECS the greater the loss of memory for the conditioning
experience
Explanations of Retrograde Amnesia
• Memory consolidation hypothesis
– Working memory is susceptible to interference and can be lost
– once enough time has passed, memory is sufficiently consolidated and
now not vulnerable to interference
– Suggests memories can be permanently lost
• However, there is a delayed onset of RA and reminder cues
can partially reverse the amnesia
– Memory failure may take minutes to hours to set in
• Anecdotal evidence from head injury
• Miller 1971 experiments with rats
– Miller 1972, reinstatement, shock only, recovery from amnesia
• Retrieval-failure hypothesis
– Amnesia due to inability to retrieve memory
– Memory is simply difficult to access, NOT lost
– With proper reminder treatments, memory should return
Retrograde Amnesia for Extinction
• Because extinction is learning new information it can be effected by
retrograde amnesia
• Briggs and Riccio (2007) Experiment One used hypothermia to
produce amnesia in a fear conditioning study
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Fear condition to a black chamber
Extinction: they are placed in the black chamber for 12 minutes
After extinction some of the rats where made hypothermic
Hypothermia at zero or 30 minutes after extinction “apparently” produces
substantial retrograde amnesia for the extinction experience
• Changes memory consolidation of extinction
– Hypothermia at 60 minutes after extinction did not change extinction
• Identifies the consolidation window
– See Figure 11.15
FIGURE 11.15
Time for rats to enter the black compartment of a shuttle box after having been shocked there. The first
group received only fear conditioning. The second group received extinction after the conditioning trial.
Groups Hypo-0, Hypy-30, and Hypo-60 received hypothermia to induce amnesia 0, 30, or 60 minutes
after the extinction procedure. (Based on Briggs & Riccio, 2007, Figure 1, p. 134.)
The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.
Explanations of Retrograde Amnesia
• Briggs and Riccio (2007) Experiment Two
• Use of reminder cues to reverse amnesia
• Same as experiment one with additional groups to look at the
effects of hypothermia during the testing
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Fear conditioned to black side
Extinquished to black side
Hypothermia after extinction to change consolidation of extinction
Hypothermia during testing see figure 11.16
• Body temperature of 30 degrees reinstated extinction
• Body temperature of 33 degrees partially reinstated extinction
• Body temperature of 37 degrees did not reinstated extinction
FIGURE 11.16
Time for rats to enter the black compartment of a shuttle box after having been shocked there. The first
group received only conditioning. The second group received extinction after the conditioning trial. The
remaining groups received a hypothermia treatment right after extinction and were tested the next day.
Group Exp/Hypo was tested without being recooled. Groups Recool 30, Recool 33, and Recool 37 were
recooled before the memory test and were allowed to warm up to body temperatures of 30, 33, and
37°C for the test session (based on Briggs & Riccio, 2007, Figure 2, p. 136).
The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.
Consolidation Failure versus Retrieval Failure
• Misanin (1968) as cited in Retrograde Amnesia: Forgetting Back
– Tone foot shock training followed by a reminder tone 24 hours later to
reactivate the memory.
– ECS given after the reminder tone produced substantial retrograde amnesia.
– Reminder tone reactivates the memory of the tone – foot shock training
which makes the memory vulnerable to ECS amnesia effects.
• state dependent memory the internal state of the organism at the
time of retrieval differs substantially from the internal state of the
organism at the time of encoding
• Understanding of amnesic effects is important for understanding
various memory disorders and developmental phenomena
– Alzheimer’s amnesia
– Infantile amnesia
• Establishing whether each represents consolidation OR retrieval
failures (or both) is critical
Consolidation, Reconsolidation, and Memory Updating
• Consolidation is a serious of processes
– Fast synaptic in minutes to hours
– Slower system in days
– can easily be reactivated by just by recalling the memory
• Reconsolidate: to consolidate again and again and again
– when you recall something from long-term memory
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thinking about information retrieved from long-term
processed again in working memory where new information can be added
this information is stored away as reconsolidated long-term memory
Can be disrupted by concussion or hypothermia
• So long-term memory is not "permanent" in the sense that they are
unalterable
• Reconsolidation can result in retrieval failure because retrieval cues
may no longer match up with the reconstructed memory
• Problem for eyewitness testimony
FIGURE 11.17
Contrasting views of memory storage and recall. In the traditional view, information first entered shortterm memory (STM) and was then consolidated for transfer to long-term memory (LTM). Memory
activation served to return the information to short-term memory but did not change the memory. In the
contemporary view, memory is either in an active or inactive state. Active memories can always be
consolidated for transfer to the inactive state, whether the information is in the active state because of
original learning or because of the activation of an old memory.
The Principles of Learning and Behavior, 7e by Michael Domjan
Copyright © 2015 Wadsworth Publishing, a division of Cengage Learning. All rights reserved.