Response Competition in the Primary Motor Cortex: Corticospinal Excitability Reflects Response Replacement During Simple Decisions
Response Competition in the Primary Motor Cortex: Corticospinal Excitability Reflects Response Replacement During Simple Decisions
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DOI：
10.1152/jn.00819.2009
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发表时间：
2010-07-01
影响因子：
2.5
通讯作者：
Cisek, Paul
中科院分区：
文献类型：
--
作者：
Michelet, Thomas;Duncan, Gary H.;Cisek, Paul
Michelet T，邓肯G，Cisek P.初级运动皮层的反应竞争：皮质脊髓兴奋性反映了简单决策过程中的反应替代。J Neurophysiol 104：119-127，2010.首次发表于2010年5月5日; doi：10.1152/jn.00819.2009。有人认为，在对行动作出决定时，最初是同时规定多种选择，然后在公开执行的竞争中逐渐消除。为了进一步验证这一假设，我们研究了埃里克森侧翼任务反应时间期间人类皮质脊髓兴奋性的调节。在这项任务中，受试者用手指弯曲或伸展来回应中央箭头，而忽略一致或不一致的侧翼箭头。单脉冲经颅磁刺激（TMS）施加在初级运动皮层（M1）在五个不同的刺激后的潜伏期之一，运动诱发电位（MEP）在对侧食指测量。在控制（没有侧翼）和一致的条件下，MEP大小的激动剂逐渐增加的反应时间的过程中，表明皮质脊髓兴奋性的增加。相反，当同一块肌肉作为拮抗剂时，MEP大小减小，表明抑制。重要的是，在不一致的条件下，MEP在肌肉中短暂增加，对应于对侧翼箭头的初始默认反应，随后被对应于对中心箭头的正确反应的MEP所取代。最后，我们发现，逐渐增长的MEP的三个条件下达到一个恒定的最大水平之前，运动开始。我们建议，这种动态调制皮质脊髓兴奋性反映了竞争的过程中，导致选择的一个响应和拒绝的其他。我们的研究结果表明，反应竞争影响初级运动皮层的活动，其时间直接影响运动输出潜伏期。
Michelet T, Duncan G, Cisek P. Response competition in the primary motor cortex: Corticospinal excitability reflects response replacement during simple decisions. J Neurophysiol 104: 119-127, 2010. First published May 5, 2010; doi:10.1152/jn.00819.2009. It has been suggested that, during decisions about actions, multiple options are initially specified in parallel and then gradually eliminated in a competition for overt execution. To further test this hypothesis, we studied the modulation of human corticospinal excitability during the reaction time of the Eriksen flanker task. In the task, subjects responded with finger flexion or extension to a central arrow while ignoring congruent or incongruent flanker arrows. Single-pulse transcranial magnetic stimulation (TMS) was applied over primary motor cortex (M1) at one of five different latencies after stimulus onset, and motor-evoked potentials (MEPs) were measured in the contralateral index finger. During the control (no flankers) and congruent conditions, MEP size in the agonist increased gradually over the course of reaction time, indicating an increase in corticospinal excitability. Conversely, when the same muscle acted as an antagonist, MEP size decreased, suggesting inhibition. Critically, in the incongruent condition, MEPs briefly increased in the muscle corresponding to an initial default response to the flanker arrows and were later replaced by MEPs corresponding to the correct response to the central arrow. Finally, we found that the gradually growing MEPs for the three conditions reached a constant maximum level just before movement initiation. We propose that this dynamic modulation in corticospinal excitability reflects the competition process, leading to the selection of one response and the rejection of the other. Our results suggest that response competition influences activity in primary motor cortex and that its timing directly influences motor output latency.