Article Figures & Data
Figures
- Figure 1.
a, The selective stopping paradigm. Trials are shown for MSR and null conditions. A cue was followed by a delay and then the go signal—a row of four circles. If the two outer circles were blue, two responses were simultaneously initiated with little fingers of each hand; if the inner circles were blue, then index fingers were used. On probe trials a red “X” occurred soon after the go signal, requiring stopping of one response and continuing the other. On null trials the subject rested. b, A single TMS stimulus was delivered over left primary motor cortex. MEPs were recorded from the right hand. c, Hypothetical MEP results for the suppression and facilitation models.
- Figure 2.
a, Preparing to stop the right hand (MSR) leads to suppression of right hand excitability beneath baseline (null) even before the response is initiated (Note: this analysis includes all trials regardless of whether they are subsequently go or stop.) b, The MEP results match the suppression model in Figure 1c. MEP data are shown for the 500 ms time point alone—see dotted rectangle in a. c, Relation between neural suppression and behavioral stopping. When preparing to stop the right hand, the MEP suppression of that hand (MSR minus null) correlates with the subsequent selectivity of stopping (the stopping interference effect). d, When preparing to stop the left hand, the MEP suppression of the right hand (MSL minus null) does not correlate with the stopping interference. The observations in c and d reflect successful stop trials only, and these are pooled across all subjects. The stopping interference effect is the probe alternative RT minus the mean of the go alternative RT for that subject. The neural measure is the size of the MEP on that trial minus the mean of the MEPs for null trials at the corresponding time point (800, 500, and 200) for that subject. Error bars show SD; *p < 0.01.
- Figure 3.
A schematic model of how proactive and selective suppression is set up and used for behaviorally selective stopping. In the proactive and selective control stage, the stopping goal “Maybe Stop Right” biases particular response channels (right hand) without affecting the execution level. In the response initiation stage, the go signal initiates two responses (left and right index fingers). In the reactive and selective stopping stage, the stop signal triggers the selective suppression mechanism that was set up previously, thus stopping the right index finger but not the left index finger.
Tables
MSL MSR Significance (p) Go cue RT (seconds) 0.576 (0.080) 0.577 (0.076) 0.915 Go alternative RT (seconds) 0.577 (0.079) 0.572 (0.080) 0.271 Go cue lead (seconds) 0.001 (0.007) −0.005 (0.009) 0.113 Go decouple rate (%) 7.4 (5.3) 8.0 (6.4) 0.523 Probe accuracy (%) 57.8 (7.0) 56.8 (7.1) 0.252 Probe fail rate (%) 36.1 (5.6) 36.8 (6.1) 0.523 Direction errors (%) 3.5 (3.3) 2.8 (4.4) 0.510 Probe alternative RT (seconds) 0.761 (0.159) 0.747 (0.156) 0.257 Stopping interference (seconds) 0.184 (0.119) 0.175 (0.123) 0.437 SSD (seconds) 0.282 (0.058) 0.278 (0.061) 0.513 SSRT (seconds) 0.294 (0.040) 0.299 (0.036) 0.539 Behavioral performance was highly similar regardless of whether the cue was MSL or MSR.
