Visual Ambiguity Constrains Motor Prediction And Corticospinal Excitability In Humans

Area of Science:

• Neuroscience
• Motor Control
• Cognitive Science

Background:

• Action observation (AO) engages predictive motor coding.
• The influence of visual uncertainty on this process, particularly on behavior and corticospinal excitability (CSE), is not fully understood.

Purpose of the Study:

• To investigate how visual uncertainty affects behavioral timing precision during action observation.
• To examine the impact of visual uncertainty on corticospinal excitability (CSE) during action observation.

Main Methods:

• Two experiments combined a behavioral timing task with action observation-transcranial magnetic stimulation (AO-TMS).
• Visual uncertainty was manipulated using naturalness, occlusion, and shape congruence in action videos.
• Corticospinal excitability (CSE) was measured via FDI motor-evoked potentials (MEPs) during AO.

Main Results:

• Behaviorally, reduced naturalness, occlusion, and incongruent shapes degraded temporal precision.
• AO generally facilitated CSE, but condition-specific modulations related to uncertainty were minimal and not statistically significant.
• Perceptual uncertainty strongly influenced behavioral predictions but had subtle effects on motor resonance.

Conclusions:

• Visual uncertainty significantly impacts behavioral timing during action observation.
• The effects of visual uncertainty on corticospinal excitability (CSE) during action observation are subtle under the tested conditions.
• The study establishes a reproducible AO-TMS protocol for future research on uncertainty and predictive motor processes.