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I. Episodic memory: Paired associates learning
Paired-associates task-design.
Observation of pairs to be memorized is followed by
12hours of wake or sleep, after which cued recall is tested.
Recall performance increases due to SWS between training and testing
II. Gist extraction: Learning meaning of Chinese characters:
A shared pattern in Chinese characters is recognized better after sleep
III. Rule extrapolation: Learning Implicit hierarchy between stimuli
Hierarchy rule is more easily recognized after sleep compared to wake
Evidence from the last decade shows that sleep has an important role in learning and memory. specifically, sleep – and especially Slow-Wave Sleep (SWS) and, sometimes, Rapid-Eye-Movement sleep (REM) – has been shown to improve
, and
In addition, it has been shown that following sleep (especially SWS) synaptic strength within cortical and hippocampal circuits is generally decreased, these two findings have often been taken to support different and even contradicting theories about the role of sleep in learning and memory. The current work in progress is a computational approach that seeks to combine a broad range of empirical findings within a uniform neuro-computational framework.
Slope and Amplitude of Excitatory Post-Synaptic Potentials
(EPSPs) in the prefrontal cortex of rats decrease following sleep compared to a Sleep-deprivation period. (W – Wake; S – Sleep;
Changes in cortical Local Field Potential (LFP) in rats in response to stimulation after a period of wake (Sleep
Deprived - SD) compared to sleep (Liu et al., 2010)
Learned patterns
Test sample
Learned patterns
Test sample
Complete the test sample with activation based on the correct learned pattern
Which of the two test samples fit better to the learned patterns?
Learned patterns
Test samples
Learned patterns
Test samples
Learned structures
Test sample
Learned structures
Test sample
To which of the two learned structures does the test sample fit?
1. Based on our previous NSF-supported modeling (Gluck and Myers, 1993; Moustafa et al., 2009) we assert that storing episodic memories, extracting gist information, or extrapolating a classification rule, all crucially depend on gradual learning of stimulusstimulus associations in the
hippocampus during wake. Only after learning these statistical regularities, can the system (Medial Temporal
Cortex and Striatum) process appropriate responses.
2. Sleep (especially SWS) provides an additional processing stage to the hippocampal representations that were acquired during wake, allowing them to become more parsimonious and consequently boost performance in the subsequent testing phase. This additional stage is based on two processes:
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: Representations with a small degree of correlations become largely uncorrelated
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: Representations that are very correlated to each other are unified to become a single representation.
3. Both of these changes are carried out by
: Differentiation is achieved by deletion of synapses that support activation of neurons common to several representations (thus causing these representations to become uncorrelated). Unification is achieved by deletion of synapses that support activation of neurons that are unique to each representation (thus allowing only neurons common to all these representations to survive, turning these separate representations into a single representation).
Gradual learning during wake
Input correlation
Supported by Grant #7367437 for “Long-term Mobile
Monitoring and Analysis of Sleep-Cognition
Relationship” from the National Science Foundation's
Smart Health and Wellbeing program to M.A.G.
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