School of Psychology, University of Newcastle, Newcastle, New South Wales, 2308, Australia.
J Neurosci. 2011 Oct 12;31(41):14688-92. doi: 10.1523/JNEUROSCI.2390-11.2011.
Adjustment of response threshold for speed compared with accuracy instructions in two-choice decision-making tasks is associated with activation in the fronto-striatal network, including the pre-supplementary motor area (pre-SMA) and striatum (Forstmann et al., 2008). In contrast, increased response conservativeness is associated with activation of the subthalamic nucleus (STN) (Frank et al., 2007). We investigated the involvement of these regions in trial-by-trial adjustments of response threshold in humans, using a cued-trials task-switching paradigm. Fully and partially informative switch cues produced more conservative thresholds than repeat cues. Repeat cues were associated with higher activation in pre-SMA and striatum than switch cues. For all cue types, individual variability in response threshold was associated with activation level in pre-SMA, with higher activation linked to lower threshold setting. In the striatum, this relationship was found for repeat cues only. These findings support the notion that pre-SMA biases the striatum to lower response threshold under more liberal response regimens. In contrast, a high threshold for switch cues was associated with greater activation in right STN, consistent with increasing response caution under conservative response regimens. We conclude that neural models of response threshold adjustment can help explain executive control processes in task switching.
在二择一决策任务中，对速度与准确性指令的反应阈限进行调整与额-纹状体网络（包括预备运动区 [pre-SMA] 和纹状体）的激活有关，而反应保守性的增加则与丘脑底核（STN）的激活有关（Forstmann 等人，2008 年；Frank 等人，2007 年）。我们使用提示试验任务转换范式，研究了这些区域在人类反应阈限的逐次调整中的参与情况。完全和部分信息性的转换提示比重复提示产生了更保守的阈限。重复提示与 pre-SMA 和纹状体中的激活水平比转换提示更高有关。对于所有提示类型，反应阈限的个体可变性与 pre-SMA 的激活水平有关，较高的激活与较低的阈限设定有关。在纹状体中，这种关系仅在重复提示中发现。这些发现支持了 pre-SMA 根据更宽松的反应方案使纹状体偏向于降低反应阈限的观点。相比之下，转换提示的高阈限与右侧 STN 的更大激活有关，这与在保守反应方案下增加反应谨慎性一致。我们得出结论，反应阈限调整的神经模型可以帮助解释任务转换中的执行控制过程。
