Fig 4. (related to S4–S6 Figs as well as S2 and S3 Tables).

Hastiness relied on a broad amplification and a surround suppression of motor excitability on the chosen side. (A) Effect of CONTEXT on motor excitability on the chosen side. The top graphs show excitability changes occurring over the decision period in the hasty and cautious contexts (blue and yellow traces, respectively). Given that the effect of context was reproducible across the 3 leg representations (see S5 Fig), the MEP data have been pooled together (right panel). The inset in the right panel denotes the main effect of context on the leg region. The bar graph at the bottom displays individual data points as obtained at Jump₇, for each context and each representation. Error bars represent 1 SEM.*: significant effect of context at p < 0.05. (B) Same as A. for the unchosen side. (C) Spatiotemporal motor maps. We computed spatiotemporal maps to provide an integrative view of motor excitability changes occurring during the course of deliberation in each context (see main text). To this aim, we considered altogether the MEPs obtained for the index, thumb, pinky, and leg representations of the chosen and unchosen sides, and we arranged them spatially according to M1 somatotopy. One spatiotemporal map was obtained for each context, and a between-context difference map was finally computed (i.e., hasty minus cautious context). The difference map (right panel) highlights the increase in excitability in the index and leg representations of the chosen side (right side of the map, green, positive values) as well as the surround suppression occurring in the thumb (more lateral) and pinky (more medial) representations (red, negative values). Besides, no noticeable between-context difference emerged on the unchosen side (left side of the map, yellow values). All individual and group-averaged numerical data exploited for Fig 4 are freely available at this link: https://osf.io/tbw7h. M1, primary motor cortex; MEP, motor-evoked potential; TMS, transcranial magnetic stimulation.