Abstract
To effectively interact with their environment, humans must often select actions from multiple incompatible options. Existing theories propose that during motoric response-conflict, inappropriate motor activity is actively (and perhaps non-selectively) suppressed by an inhibitory fronto-basal ganglia mechanism. We here tested this theory across three experiments. First, using scalp-EEG, we found that both outright action-stopping and response-conflict during action-selection invoke low-frequency activity of a common fronto-central source, whose activity relates to trial-by-trial behavioral indices of inhibition in both tasks. Second, using simultaneous intracranial recordings from the basal ganglia and motor cortex, we found that response-conflict increases the influence of the subthalamic nucleus on M1-representations of incorrect response-tendencies. Finally, using transcranial magnetic stimulation, we found that during the same time period when conflict-related STN-to-M1 communication is increased, cortico-spinal excitability is broadly suppressed. Together, these findings demonstrate that fronto-basal ganglia networks buttress action-selection under response-conflict by rapidly and non-selectively net-inhibiting inappropriate motor tendencies.
Highlights
Rapid action-selection is paramount to effective goal-directed behavior
In the Simon task, correct incongruent trial reaction times were slower compared to congruent trial reaction times (361 ms [SEM: 8] vs. 326 ms [SEM: 7]; t(20) = 9.63, p=5.92*10À09, d = 1.06), and error rates on incongruent trials were significantly increased compared to congruent trials (22.67% vs. 10.38%; t(20) = 4.6, p=0.0002, d = 1.4), indicating response-conflict
The SST was used to elicit a wellknown neural scalp-signature of motor inhibition. This signature was isolated from the EEG signal mixture using independent component analysis (ICA)
Summary
Rapid action-selection is paramount to effective goal-directed behavior. Many real-life situations simultaneously activate multiple, often incompatible motor tendencies, resulting in responseconflict (Botvinick et al, 2001; Simon and Rudell, 1967; Stroop, 1935; Yeung et al, 2004). Subsequent research has extended this picture to include the basal ganglia (BG, Brittain et al, 2012; Frank et al, 2007; Zavala et al, 2013; Zavala et al, 2014). Current models of action-selection hold that controlled, non-automatic motor activity is regulated via dynamic fronto-BG interactions (Hikosaka and Isoda, 2010; Wessel and Aron, 2017; Wiecki and Frank, 2013). It is unclear how exactly these fronto-BG networks mechanistically exert influence on the motor system during response-conflict
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