Excitability prediction of the motor cortex leg representation using EEG-TMS

Area of Science:

• Neuroscience
• Motor Control
• Brain-Computer Interfaces

Background:

• Corticospinal excitability of the motor cortex (M1) hand representation is influenced by sensorimotor mu-rhythm.
• Prediction of M1 leg representation excitability using EEG-TMS is not well understood.

Purpose of the Study:

• To investigate the predictive relationship between sensorimotor EEG signals and corticospinal excitability of the M1 leg representation.
• To explore the role of mu-rhythm phase and power, as well as other frequency bands, in predicting M1 leg excitability.

Main Methods:

• 16 healthy subjects underwent navigated focal transcranial magnetic stimulation (TMS) targeting the tibialis anterior muscle hot spot.
• Motor evoked potentials (MEPs) and electroencephalography (EEG) were recorded simultaneously.
• Hjorth montages centered over the sensorimotor cortex were used.

Main Results:

• High gamma band power positively correlated with MEP amplitude, while beta band power showed an inverse correlation.
• Mu-rhythm phase alone did not predict MEP amplitude.
• A significant interaction between mu-power and mu-phase was observed, influencing MEP amplitude.

Conclusions:

• EEG signals from the sensorimotor cortex, including mu-power/phase interaction and other frequency bands, predict corticospinal excitability of the M1 leg representation.
• These findings may guide brain-state dependent stimulation for gait and balance disorders.