Department of Psychology, University of Amsterdam, 1018 WB Amsterdam, The Netherlands.
J Neurosci. 2011 May 4;31(18):6891-9. doi: 10.1523/JNEUROSCI.5253-10.2011.
Fronto-basal ganglia pathways play a crucial role in voluntary action control, including the ability to inhibit motor responses. Response inhibition might be mediated via a fast hyperdirect pathway connecting the right inferior frontal gyrus (rIFG) and the presupplementary motor area (preSMA) with the subthalamic nucleus or, alternatively, via the indirect pathway between the cortex and caudate. To test the relative contribution of these two pathways to inhibitory action control, we applied an innovative quantification method for effective brain connectivity. Functional magnetic resonance imaging data were collected from 20 human participants performing a Simon interference task with an occasional stop signal. A single right-lateralized model involving both the hyperdirect and indirect pathways best explained the pattern of brain activation on stop trials. Notably, the overall connection strength of this combined model was highest on successfully inhibited trials. Inspection of the relationship between behavior and connection values revealed that fast inhibitors showed increased connectivity between rIFG and right caudate (rCaudate), whereas slow inhibitors were associated with increased connectivity between preSMA and rCaudate. In compliance, connection strengths from the rIFG and preSMA into the rCaudate were correlated negatively. If participants failed to stop, the magnitude of experienced interference (Simon effect), but not stopping latency, was predictive for the hyperdirect-indirect model connections. Together, the present results suggest that both the hyperdirect and indirect pathways act together to implement response inhibition, whereas the relationship between performance control and the fronto-basal ganglia connections points toward a top-down mechanism that underlies voluntary action control.
额-基底神经节通路在自主运动控制中起着至关重要的作用，包括抑制运动反应的能力。反应抑制可能通过快速的直接通路来介导，该通路连接右侧额下回（rIFG）和预备运动区（preSMA）与丘脑底核，或者通过皮层和尾状核之间的间接通路来介导。为了测试这两条通路对抑制性运动控制的相对贡献，我们应用了一种创新的有效脑连接定量方法。我们从 20 名执行西蒙干扰任务的人类参与者中收集了功能磁共振成像数据，其中偶尔会出现停止信号。一个涉及直接通路和间接通路的单一右侧模型最能解释停止试验中的大脑激活模式。值得注意的是，这个组合模型的整体连接强度在成功抑制的试验中最高。检查行为和连接值之间的关系表明，快速抑制剂表现出 rIFG 与右侧尾状核（rCaudate）之间的连接增强，而慢速抑制剂与 preSMA 和 rCaudate 之间的连接增强有关。相应地，rIFG 和 preSMA 进入 rCaudate 的连接强度呈负相关。如果参与者未能停止，所经历的干扰（西蒙效应）的大小，但不是停止潜伏期，对直接通路-间接通路模型的连接具有预测性。总的来说，这些结果表明，直接通路和间接通路都共同作用来实施反应抑制，而表现控制和额-基底神经节连接之间的关系指向了一种自上而下的机制，这种机制是自愿行动控制的基础。
