Abstract
There is converging evidence demonstrating that the ability to voluntarily stop or prevent movement is controlled via a cortico-basal ganglia-thalamocortical loop. However, the physiological mechanism underlying this network control is unclear. There is growing evidence that concurrent neural activity in different frequency ranges interact and transiently couple, raising interest for its possible role in information processing and motor control. A particular form, phase-amplitude-coupling (PAC), the instantaneous amplitude of a higher-frequency band within a signal is modulated by the instantaneous phase of a lower-frequency band of the same (or a different) signal. The present study investigated whether PAC within the subthalamic nucleus (STN), and between the STN and motor cortex (M1) contribute to the ability to voluntarily stop or prevent movement. Patients with externalized deep brain stimulation electrodes performed a stop-signal task while electroencephalography and STN local field potentials were simultaneous recorded. Patients were instructed to press a button in response to a visual go-signal but try to inhibit this response if a stop-signal was subsequently presented. The time between the go-signal and stop-signal varied using a one-up/one-down staircase algorithm based on stop success/failure. Results revealed an increase in STN-STN PAC between beta phase (10-30Hz) and high frequency oscillation amplitude (150-400Hz) during successful- compared to failed-stop trials, and a decrease in STN-M1 PAC between beta phase (10-30Hz) and gamma amplitude (50-100Hz) during successful- compared to failed-stop trials. These findings provide novel human evidence for the role of PAC within the response inhibition network and a possible mechanism underlying the ability to stop responses.Acknowledgments: Canadian Institutes of Health Research