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Secondary motor integration as a final arbiter in sensorimotor decision-making
Tarryn Balsdon1, Stijn Verdonck2, Tim Loossens2
1School of Psychology and Neuroscience, University of Glasgow, Glasgow, United Kingdom.
Plos Biology
|July 17, 2023
Summary
This study reveals motor processes actively shape sensorimotor decisions, not just follow them. A secondary leaky accumulator in motor systems better explains decision-making than single accumulation models.
Area of Science:
- Cognitive Neuroscience
- Computational Neuroscience
- Human Motor Control
Background:
- Sensorimotor decision-making models traditionally focus on a single sensory evidence accumulation stage before motor planning.
- Existing theories often overlook the potential contribution of motor system dynamics during the decision-making process itself.
Purpose of the Study:
- To propose and test a novel framework where motor processes actively participate in decision formation through a secondary leaky accumulator.
- To investigate the role of motor leak in adapting temporal smoothing and the lag between sensory and motor evidence integration.
Main Methods:
- Formal model comparison was employed to contrast the proposed dual-accumulator model against single-accumulator variants.
- Behavioral data, including choice and response times, were collected from human observers performing a categorical decision task under varying speed-accuracy trade-offs.
- Electroencephalography (EEG) data were recorded to identify neural correlates of the proposed integration processes.
Main Results:
- The proposed model with a secondary leaky motor accumulator provided a superior fit to behavioral data compared to single-accumulator models.
- Behavioral adjustments under speed-accuracy trade-offs were better explained by changes in the motor accumulator's leak rather than decision boundary adjustments.
- Neural activity patterns derived from EEG data aligned with the predictions of the dual-accumulator model, supporting its neurobiological plausibility.
Conclusions:
- Sensorimotor decision-making involves a dynamic interplay between sensory evidence accumulation and a secondary leaky motor accumulation process.
- The motor system's leak is crucial for adapting temporal integration and the timing of decisions, challenging traditional single-accumulator views.
- This framework offers a neurobiologically grounded explanation for the active role of motor processes in shaping choice behavior.
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