Abstract
Gamma activity in the subthalamic nucleus (STN) is widely viewed as a pro-kinetic rhythm. Here we test the hypothesis that rather than being specifically linked to movement execution, gamma activity reflects dynamic processing in this nucleus. We investigated the role of gamma during fast stopping and recorded scalp electroencephalogram and local field potentials from deep brain stimulation electrodes in 9 Parkinson's disease patients. Patients interrupted finger tapping (paced by a metronome) in response to a stop-signal sound, which was timed such that successful stopping would occur only in ~50% of all trials. STN gamma (60-90 Hz) increased most strongly when the tap was successfully stopped, whereas phase-based connectivity between the contralateral STN and motor cortex decreased. Beta or theta power seemed less directly related to stopping. In summary, STN gamma activity may support flexible motor control as it did not only increase during movement execution but also during rapid action-stopping.
Highlights
Previous studies have described a neuronal stopping network involving prefrontal and supplementary motor cortical regions, as well as the subthalamic nucleus (STN) (Aron et al, 2014; Jahanshahi et al, 2015; Rae et al, 2015)
Stopping performance was quantified as movement extent, which was the extent of downward movement after the stop signal relative to the amplitude of the preceding upward movement. 0% movement extent refers to a full stop. 50% describes a movement that was interrupted halfway and 100% would correspond to a full tap, i.e. failed stopping
We found that when finger tapping had to be stopped abruptly, the stop signal elicited a fast increase in 60–90 Hz gamma activity in the contralateral STN and a pronounced theta increase in cortex
Summary
Previous studies have described a neuronal stopping network involving prefrontal and supplementary motor cortical regions, as well as the subthalamic nucleus (STN) (Aron et al, 2014; Jahanshahi et al, 2015; Rae et al, 2015). The STN is well-positioned to cancel actions as it receives cortical input via the hyperdirect pathway and can inhibit the thalamus and brainstem via the basal ganglia output nuclei as well as the striatum via the globus pallidus externus (GPe) (Mink, 1996; Wei and Wang, 2016). In the GPe a subpopulation termed arkypallidal cells, which seem to receive input from the striatum and from the STN (Nevado-Holgado et al, 2014), has been linked to action cancellation (Mallet et al, 2016).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
