Striatum and pre-SMA facilitate decision-making under time pressure

TLDR

Human decision‑making occurs under time pressure, requiring a balance between speed and accuracy that is thought to be regulated by a response threshold whose neural substrate is still uncertain, with striatal activation known to release the motor system from global inhibition. In a speed‑decision experiment, participants were cued to vary response speed requirements while we modeled behavior and recorded brain activity. Cueing for speed lowered the response threshold and activated the striatum and pre‑SMA, with individual differences in activation predicting the magnitude of threshold adjustments, demonstrating that these regions increase activity during time‑pressured decisions.

Abstract

Human decision-making almost always takes place under time pressure. When people are engaged in activities such as shopping, driving, or playing chess, they have to continually balance the demands for fast decisions against the demands for accurate decisions. In the cognitive sciences, this balance is thought to be modulated by a response threshold, the neural substrate of which is currently subject to speculation. In a speed decision-making experiment, we presented participants with cues that indicated different requirements for response speed. Application of a mathematical model for the behavioral data confirmed that cueing for speed lowered the response threshold. Functional neuroimaging showed that cueing for speed activates the striatum and the pre-supplementary motor area (pre-SMA), brain structures that are part of a closed-loop motor circuit involved in the preparation of voluntary action plans. Moreover, activation in the striatum is known to release the motor system from global inhibition, thereby facilitating faster but possibly premature actions. Finally, the data show that individual variation in the activation of striatum and pre-SMA is selectively associated with individual variation in the amplitude of the adjustments in the response threshold estimated by the mathematical model. These results demonstrate that when people have to make decisions under time pressure their striatum and pre-SMA show increased levels of activation.