Many studies have examined the rapid stopping of action as a proxy of human self-control. Several methods have shown that a critical focus for stopping is the right inferior frontal cortex (rIFC). Moreover, electrocorticography (ECoG) studies have shown beta band power increases in the rIFC and in the basal ganglia for successful vs. failed stop trials, before the time of stopping elapses, perhaps underpinning a prefrontal-basal-ganglia network for inhibitory control. Here we tested whether the same signature might be visible in scalp EEG – which would open important avenues for using this signature in studies of the recruitment and timing of prefrontal inhibitory control. We used Independent Component Analysis and time-frequency approaches to analyze EEG from three different cohorts of healthy young volunteers (48 participants total) performing versions of the standard stop signal task. We identified a spectral power increase in the band 13–20Hz that occurs after the stop signal, but before the time of stopping elapses, with a right frontal topography in the EEG. This right frontal beta band increase was significantly larger for successful compared to failed stops in two of the three studies. We also tested the hypothesis that unexpected events recruit the same frontal system for stopping. Indeed, we show that the stopping-related right lateralized frontal beta signature was also active after unexpected events (and we accordingly provide data and scripts for the method). These results validate a right frontal beta signature in the EEG as a temporally precise and functionally significant neural marker of the response inhibition process.
Background
Rapid action-stopping leads to global motor suppression. This is shown by studies using Transcranial Magnetic Stimulation to measure corticospinal excitability of task-unrelated effectors, e.g., from the hand during speech-stopping. We hypothesize this global suppression relates to the subthalamic nucleus of the basal ganglia. Several STN local field potential studies in Parkinson’s patients have shown increased ß-band power during successful stopping. Here, we aimed to test whether this STN ß-band activity indexes global motor suppression measured by transcranial magnetic stimulation.
Methods
We studied nine medicated PD patients (age: 47 – 67y, mean: 55.8; 3 female) who were implanted with STN-DBS electrodes. Participants performed a vocal stop-signal task (i.e., they had to occasionally stop a vocal response) while we simultaneously recorded local field potentials from right STN and delivered transcranial magnetic stimulation to primary motor cortex to measure corticospinal excitability from a task-unrelated hand muscle (first dorsal interosseous).
Results
Replicating prior results, STN ß-band power was increased (p < .005) and corticospinal excitability was reduced (p = .024) (global motor suppression) during successful stopping. As hypothesized, such global motor suppression was greater for successful stop-trials with higher STN ß-power (median-split: p = .043), which was further evident in a negative correlation between single-trial STN ß-power and corticospinal excitability (mean r = -.176, p = .011).
Conclusion
These findings link stopping-related global motor suppression to STN ß-band activity through simultaneous recordings of STN and corticospinal excitability. The results support models of basal ganglia that propose the STN has broad motor suppressive effects.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.