The Impact of Reactivation During Sleep on the Consolidation of Abstract Information in Humans

Study Overview
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Brief Summary
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In any given cognitive domain, representations of individual elements are not independent but are organized by means of structured relations. Representations of this underlying structure are powerful, allowing generalization and inference in novel environments. In the semantic domain, structure captures associations between different semantic features or concepts (e.g., green, wings, can fly) and is known to influence the development and deterioration of semantic knowledge. The investigators recently found that humans more easily learn novel categories that contain clusters of reliably co-occurring features, revealing an influence of structure on novel category formation. However, a critical unknown is whether learned representations of structure are closely tied to category-specific elements, or whether such representations become abstract to some extent, transformed away from the experienced features. Further, if abstract structural representations do emerge, prior work provides intriguing hints that these representations may require offline consolidation during awake rest or sleep. The investigators have developed a paradigm in which carefully designed graph structures govern the pattern of feature co-occurrences within individual categories. Here the investigators implement a structure transfer extension of this paradigm in order to determine whether learning one structured category facilitates learning of a second identically structured category defined by a new set of features. This facilitation would provide evidence that structure representations are abstract to some degree. Aim 1 will use these methods to evaluate whether abstract structural representations emerge immediately during learning. Aim 2 will determine whether these representations persist, or emerge, over a delay, and whether sleep-based consolidation in particular is needed. The role of replay of recent experience during sleep will be evaluated using electroencephalography (EEG) paired with closed-loop targeted memory reactivation (TMR), a technique that enables causal influence over the consolidation of recently learned information in humans. This work will inform and constrain theories of semantic learning as well as theories of structure learning and representation more broadly.

Official Title
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The Emergence of Abstract Structure Knowledge Across Learning and Sleep

Conditions
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Memory Consolidation

Intervention / Treatment
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* Behavioral: Congruent vs. Incongruent
* Behavioral: Immediate vs. Awake vs. Asleep
* Behavioral: Targeted memory reactivation (TMR)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Ages between 18 and 35 Exclusion Criteria: No medical or neurological illness that would impact experimental performance Not a member of a vulnerable population

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Immediate Congruent<br>Participants will learn and be tested on two different semantic categories with the same structure that dictates the co-occurrence of different features. | Behavioral: Congruent vs. Incongruent<br>* The Congruent vs. Incongruent intervention relates to the feature-based structure of the novel categories (Modular or non-Modular) and whether there is (Congruent) or is not (Incongruent) a match between what was previously learned and the final target category.<br>Behavioral: Immediate vs. Awake vs. Asleep<br>* Immediate, Awake, and Sleep refer to either no break, 2.5 hours awake, or 2 hours asleep plus a 30-minute post-nap break to account for sleep inertia between learning and target category.<br>|
| Experimental: Immediate Incongruent<br>Participants will learn and be tested on two different semantic categories with different structures that dictate the co-occurrence of different features. | Behavioral: Congruent vs. Incongruent<br>* The Congruent vs. Incongruent intervention relates to the feature-based structure of the novel categories (Modular or non-Modular) and whether there is (Congruent) or is not (Incongruent) a match between what was previously learned and the final target category.<br>Behavioral: Immediate vs. Awake vs. Asleep<br>* Immediate, Awake, and Sleep refer to either no break, 2.5 hours awake, or 2 hours asleep plus a 30-minute post-nap break to account for sleep inertia between learning and target category.<br>|
| Experimental: Awake Incongruent<br>Participants will learn two different semantic categories, neither of which has a Modular structure. After a 2.5-hour break, they will learn and be tested on a novel semantic category with a Modular structure. | Behavioral: Congruent vs. Incongruent<br>* The Congruent vs. Incongruent intervention relates to the feature-based structure of the novel categories (Modular or non-Modular) and whether there is (Congruent) or is not (Incongruent) a match between what was previously learned and the final target category.<br>Behavioral: Immediate vs. Awake vs. Asleep<br>* Immediate, Awake, and Sleep refer to either no break, 2.5 hours awake, or 2 hours asleep plus a 30-minute post-nap break to account for sleep inertia between learning and target category.<br>|
| Experimental: Awake Congruent<br>Participants will learn two different semantic categories, one of which has a Modular structure. After a 2.5-hour break, they will learn and be tested on a novel semantic category with a Modular structure. | Behavioral: Congruent vs. Incongruent<br>* The Congruent vs. Incongruent intervention relates to the feature-based structure of the novel categories (Modular or non-Modular) and whether there is (Congruent) or is not (Incongruent) a match between what was previously learned and the final target category.<br>Behavioral: Immediate vs. Awake vs. Asleep<br>* Immediate, Awake, and Sleep refer to either no break, 2.5 hours awake, or 2 hours asleep plus a 30-minute post-nap break to account for sleep inertia between learning and target category.<br>|
| Experimental: Sleep Incongruent<br>Participants will learn two different semantic categories, one of which has a Modular structure. After a 2-hour nap opportunity, during which TMR will be used to reactivate the non-Modular category, participants will take a 30-minute break. After the break, they will learn and be tested on a novel semantic category with a Modular structure. | Behavioral: Congruent vs. Incongruent<br>* The Congruent vs. Incongruent intervention relates to the feature-based structure of the novel categories (Modular or non-Modular) and whether there is (Congruent) or is not (Incongruent) a match between what was previously learned and the final target category.<br>Behavioral: Immediate vs. Awake vs. Asleep<br>* Immediate, Awake, and Sleep refer to either no break, 2.5 hours awake, or 2 hours asleep plus a 30-minute post-nap break to account for sleep inertia between learning and target category.<br>Behavioral: Targeted memory reactivation (TMR)<br>* Targeted memory reactivation (TMR) is the systematic presentation of sounds during sleep that were associated with certain stimuli during learning and will be administered either during slow wave sleep (SWS) or rapid eye movement (REM) sleep.<br>|
| Experimental: Sleep Congruent (SWS)<br>Participants will learn two different semantic categories, one of which has a Modular structure. After a 2-hour nap opportunity, during which TMR will be used to reactivate the Modular category during slow wave sleep (SWS), participants will take a 30-minute break. After the break, they will learn and be tested on a novel semantic category with a Modular structure. | Behavioral: Congruent vs. Incongruent<br>* The Congruent vs. Incongruent intervention relates to the feature-based structure of the novel categories (Modular or non-Modular) and whether there is (Congruent) or is not (Incongruent) a match between what was previously learned and the final target category.<br>Behavioral: Immediate vs. Awake vs. Asleep<br>* Immediate, Awake, and Sleep refer to either no break, 2.5 hours awake, or 2 hours asleep plus a 30-minute post-nap break to account for sleep inertia between learning and target category.<br>Behavioral: Targeted memory reactivation (TMR)<br>* Targeted memory reactivation (TMR) is the systematic presentation of sounds during sleep that were associated with certain stimuli during learning and will be administered either during slow wave sleep (SWS) or rapid eye movement (REM) sleep.<br>|
| Experimental: Sleep Congruent (REM)<br>Participants will learn two different semantic categories, one of which has a Modular structure. After a 2-hour nap opportunity, during which TMR will be used to reactivate the Modular category during rapid eye movement (REM) sleep, participants will take a 30-minute break. After the break, they will learn and be tested on a novel semantic category with a Modular structure. | Behavioral: Congruent vs. Incongruent<br>* The Congruent vs. Incongruent intervention relates to the feature-based structure of the novel categories (Modular or non-Modular) and whether there is (Congruent) or is not (Incongruent) a match between what was previously learned and the final target category.<br>Behavioral: Immediate vs. Awake vs. Asleep<br>* Immediate, Awake, and Sleep refer to either no break, 2.5 hours awake, or 2 hours asleep plus a 30-minute post-nap break to account for sleep inertia between learning and target category.<br>Behavioral: Targeted memory reactivation (TMR)<br>* Targeted memory reactivation (TMR) is the systematic presentation of sounds during sleep that were associated with certain stimuli during learning and will be administered either during slow wave sleep (SWS) or rapid eye movement (REM) sleep.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Structure knowledge for a new Modular category in Stage 2 | Accuracy (0-100%) on the missing feature task in Stage 2 | In Aim 1, accuracy is collected in a missing feature task 25 min. into the experiment, taking 25 min. In Aim 2, accuracy is collected in a missing feature task over 25 min in Stage 2 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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memory, sleep, learning