Memory Consolidation: Transformation Collaborators Rebecca Gomez Almut Hupbach Oliver Hardt
Jan 30, 2016
Memory Consolidation: Transformation
CollaboratorsRebecca GomezAlmut HupbachOliver Hardt
EVENT ENCODE CONSOLIDATE FIXED MEMORY
EVENT ENCODE CONSOLIDATE FIXED MEMORY
REACTIVATION
SLEEP
EVENT ENCODE CONSOLIDATE FIXED MEMORY
REACTIVATION
RECONSOLIDATION
PROTEIN SYNTHESIS INHIBITORS
UNFIXED MEMORY
EVENT ENCODE CONSOLIDATE FIXED MEMORY
REACTIVATION
RECONSOLIDATION
NEW/ALTERED EXPERIENCE
TRANSFORMED MEMORY
EVENT ENCODE CONSOLIDATE TRANSFORMED MEMORY
REACTIVATION
SLEEP
Reactivation Transformation
Set 1 Set 2
Reactivation Transformation
Basic Design
Group DAY 1(Monday)
DAY 2(Wednesday)
DAY 3(Friday)
Reminder Learn Set 1 Same context, same experimenter, reminder questionLearn Set 2
Recall Set 1
No-Reminder Learn Set 1 Different context, different experimenter, no questionLearn Set 2
Recall Set 1
Interference Control
Learn Set 1 - Recall Set 1
Reminder Updating Effect
Hupbach, Gomez, Hardt & Nadel, Learning & Memory, 2007
N = 12 in all groups
% R
ecal
l
REMINDER NO REMINDER CONTROL
Set 1 Items
Set 2 Items
Immediate Recall: Reconsolidation or Retroactive Inhibition
Hupbach, Gomez, Hardt & Nadel, Learning & Memory, 2007
N = 12 in all groups
Source Confusion?
Hupbach, Gomez, Hardt & Nadel, Learning & Memory, 2007
N = 12 in both groups
Absence of intrusions from Set 1 into Set 2 -- effect is asymmetrical and not simple source confusion
REMIND NO REMIND
Set 1 Items
Set 2 Items
Persistence of Updated Memory: Delayed RecallMonday: learn set 1Wednesday: remind or not, learn set 21 or 2 weeks later: recall either Set 1 or Set 2
unpublished
The effect persists for at least 2 weeks, suggesting it is a real change in memory
Persistence: Delayed Reactivation1st Monday: learn set 1 2nd Monday: remind, learn set 23rd Monday: recall Set 1
Hupbach, Gomez, Hardt & Nadel, unpubl.
The effect can be elicited at least a week after initial storage of a memory
What Triggers Updating?Group DAY 1
(Monday)DAY 2 (Wednesday)
DAY 3 (Friday)
Context (C) Learn Set 1 Same context, new experimenter, no questionLearn Set 2
Recall Set 1
Experimenter (E) Learn Set 1 Different context, same experimenter, no questionLearn Set 2
Recall Set 1
Question (Q) Learn Set 1 Different context, new experimenter, reminder questionLearn Set 2
Recall: Set 1
Reminder Effects - One Cue
Hupbach, Gomez, Hardt & Nadel, 2008.
N = 12 in all groups
Reminder Effects -- Two Cues
Hupbach, Gomez, Hardt & Nadel, 2008.
N = 12 N = 8 N = 12
Context & Experimenter Context & Question Question & Experimenter
Set 1 Items
Set 2 Items
Imagining Context
Hupbach, Gomez, Hardt & Nadel, unpubl.
Set 1 Items
Set 2 Items
N = 12
Conclusions re Context
• Context reminder critical to updating and reconsolidation– Recall acts as another training trial, does not initiate update
• In episodic memory context determines whether – new memory formed
OR – old memory updated
• Similar result seen in place cell “remapping” studies
• BUT, a caveat re the role of context
Testing in a familiar context: 5 year-olds at home
Context alone fails to elicit updating in a familiar context
Testing in a familiar context: 5 year-olds at home
Context alone fails to elicit updating in a familiar context
5 year-olds tested in day-care setting
N = 11 N = 7
But, context alone does elicit updating in an unfamiliar context
REMIND NO REMIND
Set 1 Items
Set 2 Items
Bigger Picture
• Memory is not fixed - perhaps ever– Misinformation effect– Hindsight bias
• Adaptive nature of memory malleability• What then is “consolidation”?
– Not strengthening but transforming, assimilating
Sleep Transformation
Study effects of sleep by exposing infants to material prior to a nap and testing afterwards
Design
• Toddlers exposed to material 4 hrs before lab visit (48 15-month-olds)
• Conditions (exposure to an artificial language)– Nap– No Nap– Nap control
• A Minimitter actiwatch with computer driven chip attached to infant’s ankle and used to record body movements
Language 1 Language 2
S{ aXbcXd }
S { aXdcXb }
X x1, x2, ….xn
Nonadjacent dependency learning
15-month-olds Familiarized with one of two artificial languages
vot-kicey-jic, pel-wadim-rud……
Gómez (2002)Gómez & Maye (2005)
Variability manipulation
|X| = 12
X1
X2
X3
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.X12
ac
bd
|X| = 24
X1
X2
X3
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.X24
ac
bd
|X| = 3
X1
X2
X3
ac
bd
Gómez (2002); Gómez & Maye (2005)• Nonadjacent dependencies heard equally often in each condition • Difference between conditions was size of pool from which middle element drawn.
• Learners only track non-adjacencies when adjacent dependencies are sufficiently low, when |X| = 24.
Variability manipulation|X| = 12
X1
X2
X3
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.X12
ac
bd
|X| = 24
X1
X2
X3
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.X24
ac
bd
|X| = 3
X1
X2
X3
ac
bd
Nap control
Nap and No-nap groups
Familiarization
15-minute incidental exposure
vot wadim jic | pel kicey rud | vot coomo jic | vot kicey jic | pel gople rud | vot fengle jic | pel benez rud | pel wadim rud | vot loga jic | pel vamey rud | pel taspu rud | pel fengle rud | vot hiftam jic……….
pel wadim rud vs. pel wadim jic
Test
Head-turn preference procedure
Infant controls the amount of exposure on any given trial
Veridical memory vs. abstraction
• Infants could remember specific information about strings themselves
• Or, could acquire a rule focusing on relationship between nonadjacent pairs. If so, they should detect nonadjacent dependencies in novel strings.
• Responses scored according to veridical memory and abstraction.
Predictions
• Sleep (or delay) could change memory quantitatively or qualitatively – If delay is triggering factor, nap and no-nap infants will
perform identically – If sleep is trigger then performance should differ
between nap and no-nap conditions
Naps promote abstraction!
Gómez, Bootzin, & Nadel (2006)
Mea
n lo
okin
g tim
es (s
ec)
*
*
Veridical Memory
Abstraction: Difference conditional on first post-sleep trial
What are infants learning?
• Abstraction may take form of a greater weighting given to relationship between first and third words in strings
• This weighting translates into detection of nonadjacent dependencies in similar (but not identical) strings.
Additional questions1. Is the abstraction effect a transient one, caused
by infants being more rested after a nap, or can we observed it 24 hours later before their nap?
• 15-month-olds tested 24 hrs later in Nap condition
2. Is the abstraction effect dependent on an immediate nap, or like adults, will any sleep within a 24-hour period do?
• 15-month-olds tested 24 hrs later in No-nap condition
Is the effect dependent on infants being well-rested? No, it occurs 24-hours later before a new nap
Hupbach, Gómez, Bootzin, & Nadel (in press)
Mea
n lo
okin
g tim
e di
ffere
nces
(sec
)
Veridical Memory
Abstraction: Difference conditional on first post-sleep trial*
Is the effect dependent on an immediate nap? Yes. 24-hours later there was no retention in the No-nap condition
Hupbach, Gómez, Bootzin, & Nadel (in press)
Mea
n lo
okin
g tim
e di
ffere
nces
(sec
)
Veridical Memory
Abstraction: Difference conditional on first post-sleep trial*
Summary
• Infants in Nap and No-nap conditions were exposed to an artificial language 4 or 24 hours prior to test.
• No immediate nap: Infants retained veridical memory over a 4-hour delay but showed no retention over 24 hours.
• Immediate nap: Sleep facilitated abstraction 4 and 24 hours after exposure.
How could sleep make memory abstract?
1. Sensitivity to both specific and abstract information initially, but weight these differently before and after sleep
2. Forget specific details of stimulus with sleep3. Sleep protracts learning-dependent processing
necessary for extraction of general patterns (O’Reilly & Rudy, 2000; Wilson & McNaughton, 1994)
Implications
• Transformation occurring with sleep introduces flexibility– Infants detected general pattern in artificial language whether it
was instantiated exactly as before or not. • Abstraction is a crucial form of memory change for
developing learners who must retain key aspects of experience while generalizing to new information.
• Sleep appears to be instrumental in this process