Prefrontal control over motor cortex cycles at beta frequency during movement inhibition

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Motor Control

Background:

• Successful response inhibition involves complex brain networks, with the right inferior frontal gyrus (r-IFG) and right presupplementary motor area (r-preSMA) being key.
• The precise mechanism by which these prefrontal regions communicate inhibitory signals to the primary motor cortex (M1) remains unclear.
• Brain oscillations are theorized to facilitate neuronal communication, suggesting inhibitory signals might be transmitted via specific oscillatory frequencies.

Purpose of the Study:

• To investigate the temporal dynamics of prefrontal-to-motor cortex connectivity during response inhibition.
• To determine if inhibitory signals are transmitted via specific brain oscillation frequencies.
• To establish a link between effective cortical connectivity and oscillatory activity in motor control.

Main Methods:

• Utilized double-coil transcranial magnetic stimulation (TMS) combined with electroencephalography (EEG).
• Assessed instantaneous prefrontal-to-motor cortex connectivity during a Go/NoGo task.
• Analyzed connectivity as a function of delay from cue onset in NoGo trials.

Main Results:

• Found that conditioning TMS pulses to prefrontal areas modulated motor cortex excitability specifically at beta frequency during NoGo trials.
• Observed a coinciding frontocentral beta signature in EEG during these inhibitory periods.
• Demonstrated a direct link between effective cortical connectivity and beta oscillatory activity.

Conclusions:

• Endogenous inhibitory motor signals are transmitted via beta bursts within large-scale cortical networks.
• This beta-band communication is essential for effective top-down inhibitory motor control.
• The findings provide novel insights into the neural mechanisms underlying response inhibition.