Direct evidence for a binding between cognitive and motor functions in humans: a TMS study

Area of Science:

• Neuroscience
• Motor Control
• Cognitive Neuroscience

Background:

• Cortico-spinal (CS) excitability is modulated by both cognitive intention and motor performance during voluntary actions.
• Understanding the interaction between these processes is crucial for motor control research.

Purpose of the Study:

• To investigate how cognitive and motor processes interact in modulating CS excitability during voluntary wrist movements.
• To dissociate intention-related and performance-related processes influencing CS excitability.

Main Methods:

• Utilized transcranial magnetic stimulation (TMS) to quantify CS excitability via motor-evoked potentials (MEPs).
• Subjects prepared to either "let go" or "resist" a TMS-induced movement, allowing dissociation of intention and performance.
• Analyzed MEPs and motor performance in successful and unsuccessful trials.

Main Results:

• Subjects could cognitively prepare to resist TMS-induced perturbations, reporting significant cognitive effort.
• Short-latency MEP amplitude correlated continuously with actual movement, irrespective of prior intention.
• Anticipatory modulation of CS excitability was selective and efficient, supporting intended motor behavior.

Conclusions:

• Prior intention enables anticipatory modulation of CS excitability, crucial for successful motor execution.
• CS excitability plays a direct role in integrating cognitive intentions with motor outputs in humans.
• This study provides direct evidence for the role of CS excitability in binding cognitive and motor processes.