Phase-targeted peripheral stimulation modulates cortical sensorimotor responses.

Area of Science:

• Neuroscience
• Sensorimotor Integration
• Brain-Computer Interfaces

Background:

• Brain oscillations modulate sensory processing.
• Cortical responses to peripheral stimulation depend on timing relative to brain activity.
• The precise relationship between EEG phase and evoked potentials from targeted stimulation is not fully understood.

Purpose of the Study:

• To investigate the cortical signatures of EEG phase-targeted peripheral stimulation across various frequencies.
• To determine if the timing of neuromuscular electrical stimulation (NMES) relative to EEG phase influences evoked potentials.
• To characterize the frequency and phase dependence of stimulation-evoked potentials.

Main Methods:

• Delivered single-pulse NMES to the extensor digitorum communis muscle in 19 healthy adults.
• Triggered NMES timing in real-time to predefined EEG phase targets across 4-40 Hz.
• Analyzed stimulation-evoked potentials (P30, N60, N120, P190) using a two-stage approach, testing phase dependence via cosine-model fits.

Main Results:

• Identified canonical evoked potential components (P30, N60, N120, P190).
• Observed a candidate pattern for the late P190 component at 16 Hz.
• Maximal P190 responses occurred when NMES was triggered at 45° phase, corresponding to the early rising EEG phase.

Conclusions:

• Peripheral stimulation timing relative to ongoing EEG phase can influence late cortical sensorimotor responses.
• The strongest candidate effect was observed in late evoked activity (P190), suggesting an impact on higher-order sensorimotor processing.
• This highlights the potential for precise timing of peripheral input to modulate neural processing based on brain oscillatory states.