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A Trial-by-Trial Window into Sensorimotor Transformations in the Human Motor Periphery
Chao Gu1, Daniel K Wood2, Paul L Gribble3
1Department of Psychology and Brain and Mind Institute and.
Summary
The stimulus-locked response (SLR) in human limbs reflects visual location even during opposing movements. Cognitive control modulates SLR magnitude, offering insights into visual processing and motor commands.
Area of Science:
- Neuroscience
- Motor Control
- Human Physiology
Background:
- A rapid stimulus-locked response (SLR) occurs in the motor periphery within 100 ms of visual stimulus onset.
- The tectoreticulospinal pathway is a proposed relay for the SLR, integrating visual and motor signals.
Purpose of the Study:
- To investigate how cognitive control modulates the SLR during goal-directed upper limb movements.
- To determine if the SLR encodes stimulus location or movement goal during pro-reaches and anti-reaches.
- To explore the relationship between SLR magnitude, reaction time, and cognitive demands.
Main Methods:
- Recorded SLRs from an upper limb muscle during voluntary reaches toward (pro-reach) and away from (anti-reach) a visual stimulus.
- Analyzed SLR magnitude and its correlation with movement direction and reaction time.
- Compared SLR characteristics between correct and error trials during anti-reaches.
Main Results:
- SLRs on anti-reaches encoded stimulus location, not the movement goal.
- SLR magnitude was attenuated when reaching away from the stimulus compared to reaching toward it.
- SLR magnitude correlated inversely with reaction time for pro-reaches and directly for anti-reaches.
- SLR attenuation correlated with cognitive control demands in anti-reaches, with greater attenuation preceding shorter reaction times.
Conclusions:
- Task-related cognitive control signals modulate visual information processed through the tectoreticulospinal pathway.
- The SLR provides a dynamic, trial-by-trial measure of how cognitive control influences early visual processing in humans.
- Findings suggest a conserved mechanism for sensorimotor integration across different motor tasks and species.
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