Real-time cortical dynamics during motor inhibition.

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Human Motor Control

Background:

• Action inhibition is a critical executive function involving intricate neural networks.
• Understanding the real-time brain dynamics during action inhibition remains a challenge.
• Existing methods have limitations in capturing dynamic neural processes.

Purpose of the Study:

• To investigate real-time effective brain dynamics during action inhibition using a novel TMS-EEG approach.
• To explore cortico-cortical connectivity changes in supplementary motor cortex (SMA) and primary motor cortex (M1) during response inhibition.
• To elucidate the neural mechanisms underlying motor control and response inhibition.

Main Methods:

• Combined transcranial magnetic stimulation (TMS) with simultaneous electroencephalographic (EEG) recordings in 22 healthy volunteers.
• Participants performed a Go/NoGo task while TMS was applied to the M1 hand-hotspot.
• Source-based real-time spatiotemporal dynamics and cortico-cortical connectivity were reconstructed.

Main Results:

• Observed task-dependent, bi-directional changes in theta/gamma SMA-M1 connectivity.
• Inhibition of response increased a specific TMS-evoked EEG potential (N100), suggesting GABA-mediated inhibition.
• TMS perturbation revealed long-lasting modulation of SMA-M1 natural frequencies (alpha/beta activity).
• Connectivity changes were linearly related to reaction times during motor responses.

Conclusions:

• The study provides novel insights into the real-time neural dynamics of action inhibition.
• Findings highlight the role of SMA-M1 connectivity and GABAergic mechanisms in motor control.
• The results offer a deeper understanding of the physiological basis of response inhibition in humans, with potential parallels in animal models.