Reshaping the Motor Engram - An Online Crowdsourcing Study.

Study Overview
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Brief Summary
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A critical point in learning and memory research is whether memories, once consolidated, remain unchanged or whether they continue to undergo plastic changes and remodeling. While previous research has focused on experimental destabilization during early stages of the memory life cycle, i.e., during encoding or early consolidation, experimental data that provides information about the effect of destabilization interventions on well-consolidated memories is still missing. This is particularly true for the procedural memory domain, such as learning a sensorimotor skill. This project is designed to characterize the effect of a single behavioral interference intervention on a previously consolidated sensorimotor skill in a large sample of healthy volunteers recruited through an online crowdsourcing platform. In a longitudinal design, participants will perform an implicit sequence learning task over five consecutive sessions, followed by an interference intervention in session six and a follow-up evaluation of the stability of the learned skill in session seven. The experimental design includes two levels of sequential information (spatial and temporal), which allows the testing of the specificity of the interference intervention. Behavioral performance throughout the experimental sessions is acquired via the manual input on the participants' computer keyboards and used to extract the learning rate and the interference effect (primary outcome).

Official Title
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Reshaping the Motor Engram - An Online Crowdsourcing Study.

Conditions
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Healthy Volunteers

Intervention / Treatment
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* Behavioral: Interference through learning of a competing motor skill.
* Behavioral: No interference


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: registered Amazon Mechanical Turk users (called 'workers') with >95% approval rate on all previous Amazon Mechanical Turk assignments location in North America or Europe ≥18 years of age not having participated in this experiment before Exclusion Criteria: • prior participation in this experiment

Ages Eligible for Study
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Minimum Age: 18 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: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Interference on sequence 1<br>The interference intervention (session six) will be applied to one of the two previously learned sequences (temporal). | Behavioral: Interference through learning of a competing motor skill.<br>* Interference through the learning of a competing motor skill.<br>|
| Experimental: Interference on sequence 2<br>The interference intervention (session six) will be applied to one of the two previously learned sequences (spatial). | Behavioral: Interference through learning of a competing motor skill.<br>* Interference through the learning of a competing motor skill.<br>|
| Experimental: Interference on sequences 1 and 2<br>The interference intervention (session six) will be applied to both of the two previously learned sequences (temporal and spatial). | Behavioral: Interference through learning of a competing motor skill.<br>* Interference through the learning of a competing motor skill.<br>|
| Sham Comparator: No interference<br>The interference intervention (session six) will be applied. | Behavioral: No interference<br>* No interference through the continuation of learning same motor skill<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Immediate interference rate (change in performance precision) | Performance in the learning task is derived from the precision of timing of key presses relative to the occurrence and duration of visual cues presented on the computer screen. The interference rate is operationalized as the change in performance precision over time. The immediate interference effect is analyzed based on the change in performance from before (pre-interference) the interference intervention to directly after the interference intervention in session six (post-interference). This change is normalized to the performance at baseline (pre-interference session six) and computed as [(post-interference - pre-interference)/pre-interference*100]. | six days | 
| Delayed interference rate (change in performance precision) | The delayed interference rate is calculated in analogy to the immediate interference effects with a 24-hours latency of the post-interference measure. Delayed interference is analyzed based on the change in performance from before the interference intervention (pre-interference in session six) to 24 hours after the interference intervention in session seven (24hours post-interference). This change is normalized to the performance at baseline (pre-interference session six) and computed as [(24 hours post-interference - pre-interference)/pre-interference*100]. | seven days | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Learning rate (change in performance precision) | Skill learning is defined based on the precision of timing of key presses relative to the occurrence and duration of visual cues presented on the computer screen. Skill learning is indexed by increased precision over time, operationalized as declining deviation of key on- and offsets from the timing of cue on- and offsets. Learning rate is the absolute change of precision over the learning phase of five days, which is expected to follow an asymptotic exponential function. | five days |