nsf science of learning
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NSF Science of Learning. Lila Davachi Dept Psychology and Neural Science New York University. Introduction. We ’ ve known the hippocampus and MTL are critical for new memories to become consolidated Decades of work to understand how the hippocampus (in particular) supports memory - PowerPoint PPT PresentationTRANSCRIPT
NSF Science of Learning
NSF Science of Learning
Lila DavachiDept Psychology and Neural Science
New York University
IntroductionWe’ve known the hippocampus and MTL are critical for new memories to become consolidated
Decades of work to understand how the hippocampus (in particular) supports memory
Divergence in the field - Rodent physiologists mostly studying spatial learning- Psychologists studying word-list learning- They could not be more different
Recent convergence (worth exploring further!)- Reactivation mechanism for memory consolidation- Sequences critical!
Related accomplishments- Reactivation facilitates building complex knowledge
structures through ‘integrative learning’
Objectives
• 1. Reactivation
• Mechanism for consolidation during awake rest
• More general mechanism for integrative learning
2. Active Learning
Objectives
• 1. Reactivation
• Mechanism for consolidation during awake rest
• More general mechanism for integrative learning
2. Active Learning
Systems consolidation is a process of trace reorganization proposed to shift the memory representation from a hippocampal-dependent to a hippocampal-independent representation.
Hypothesized to be achieved through both online and offline hippocampal-cortical interactions that occur after the initial learning.
Specifically, ‘replay’ of the pattern of activity linked with the initial experience has been hypothesized to be at least one mechanism supporting memory consolidation
Systems consolidation of memory
Background
Hippocampal neural ‘replay’ has been shown in the rodent both during sleep (Pavlides & Winson, 1989; Wilson & McNaughton, 1994) and during awake rest (Foster & Wilson, 2006; Diba & Buzsaki, 2007).
Critically, recent work has shown that selective suppression of hippocampal replay during offline periods can impair spatial memory (Girardeau et al, 2009; Ego-Stengel & Wilson, 2010)
Hippocampal Replay
When does reactivation occur?
Con
scio
usn
ess
time
Retrieval
Off-line
Experience
When does reactivation occur?
Con
scio
usn
ess
time
Retrieval
Off-line
Experience
Off-line?Sleep
Awake rest?Brain region resting?
Awake rest and memory consolidation
r = .37
(Tambini, Ketz and Davachi ,2010, Neuron)
BaselineRest
Post-TaskRest
Object-FaceTask
8.4 mins 8.4 mins21 mins
r = .37 r = .60r = .37
Awake rest and memory consolidation
(Tambini, Ketz and Davachi ,2010, Neuron)
BaselineRest
Post-TaskRest
Object-FaceTask
8.4 mins 8.4 mins21 mins
Resting Hippocampal-LO correlations
Assoc hits > misses
(Tambini, Ketz and Davachi ,2010, Neuron)
Change in correlations predict later memory for the preceding
representations
(Tambini, Ketz and Davachi, 2010, Neuron)
• Reactivation of patterns of activity across cells is specific
Patterns of replay?
Sutherland and McNaughton, CONB 2000
Sleep before task Sleep after task
Encoding Task
task- Base-rest
similarity =
.26 task
-Pos
t-res
t
simila
rity
= .5
6
Baseline Rest Post-Task Rest
• Reactivation is seen during immediate post-encoding rest periods
• Initial evidence that this can be seen at the level of single voxels in their patterns of activation with other voxels
• The magnitude of reactivation is related to later memory
• How long a rest period needed?
• What counts as rest?
Summary
Objectives
• 1. Reactivation
• Mechanism for consolidation during awake rest
• More general mechanism for integrative learning
2. Active Learning
Integration during learning:mediated by reactivation
(Zeithamova et al, 2012, Neuron)
Integration during learning:mediated by reactivation
(Zeithamova et al, 2012, Neuron)
Summary• Reactivation during new encoding can enhance memory
updating/integration
• Using multivariate methods, can measure the reactivation of categorical representations. This methodological innovation opens many doors to understanding how and when reactivation occurs and when is it beneficial/detrimental?
• How could this be leveraged to enhance conceptual learning?
• How much can be reactivated at once?
• How effect reactivation? Single cue? Context?
Reactivation different functions?
• Reactivation during sleep/awake rest/online tasks?
• Possibilities:
• Reactivation during sleep: integrating into existing knowledge?
• Awake rest: good for strenghthening?
• On line tasks: good for updating?
Objectives
• 1. Reactivation
• Mechanism for consolidation during awake rest
• More general mechanism for integrative learning
2. Active Learning
Active Learning
• Hypothesis testing? Using what we know we don’t know to select information?
• Recent work suggests that just the act of selecting, itself, may enhance encoding
• Action systems in the brain rely on dopamine, for e.g. to reinforce appropriate behaviors
• Is it possible then when learning in an active manner, the brain brings on another system that may not be technically ‘needed’ but that has the consequence of enhancing learning?
Active Learning
Active Learner
‘Yolked’ LearnerVoss et al, 2011, Nature Neuroscience
Active Learning
Memory is enhanced!
Active Learning
• Different levels of ‘active’
• Possibility that simply pressing a button can leverage another system (dopamine) and enhance long-term retention of representations
• Think iPAD!