Reward Prediction Error Modulates Saccade Vigor
Reward Prediction Error Modulates Saccade Vigor
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DOI：
10.1523/jneurosci.0432-19.2019
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发表时间：
2019-06-19
影响因子：
5.3
通讯作者：
Shadmehr, Reza
中科院分区：
文献类型：
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作者：
Sedaghat-Nejad, Ehsan;Herzfeld, David J.;Shadmehr, Reza
运动活力被定义为从获得奖励到获得奖励的潜伏期的倒数，随着奖励的大小而变化：运动表现出更短的反应时间和更高的速度，当它们被导向更多的奖励刺激时。这种活力可能是由于运动开始之前多巴胺的释放，这已被证明是由发出奖励预测错误（RPE）信号的事件调节的。在这里，我们在运动开始前的几毫秒内产生了一个RPE事件，并测试了RPE和活力之间是否存在关系。人类受试者（两性）对图像进行扫视。在执行主要扫视期间，我们概率性地改变该图像的位置和内容，鼓励二次扫视。在一些试验中，次级图像的内容比第一图像更有价值，导致在次级扫视之前的正RPE（+RPE）事件。在其他试验中，该内容的价值较低（-RPE事件）。我们发现，反应时间的二次扫视的影响，在一个有序的方式由先前的RPE事件的大小和方向：最有力的扫视其次是最大的+ RPE，而最不积极的扫视其次是最大的RPE。次级扫视的存在表明初级扫视经历了运动错误，诱导试验到试验的适应。然而，这种从运动错误中的学习并不受RPE事件的调节。这些数据表明，RPE事件，被认为是短暂改变多巴胺的释放，调节随后的运动的活力。
Movement vigor, defined as the reciprocal of the latency from availability of reward to its acquisition, changes with reward magnitude: movements exhibit shorter reaction time and increased velocity when they are directed toward more rewarding stimuli. This invigoration may be due to release of dopamine before movement onset, which has been shown to be modulated by events that signal reward prediction error (RPE). Here, we generated an RPE event in the milliseconds before movement onset and tested whether there was a relationship between RPE and vigor. Human subjects (both sexes) made saccades toward an image. During execution of the primary saccade, we probabilistically changed the position and content of that image, encouraging a secondary saccade. On some trials, the content of the secondary image was more valuable than the first image, resulting in a positive RPE (+RPE) event that preceded the secondary saccade. On other trials, this content was less valuable (-RPE event). We found that reaction time of the secondary saccade was affected in an orderly fashion by the magnitude and direction of the preceding RPE event: the most vigorous saccades followed the largest + RPE, whereas the least vigorous saccades followed the largest-RPE. Presence of the secondary saccade indicated that the primary saccade had experienced a movement error, inducing trial-to-trial adaptation. However, this learning from movement error was not modulated by the RPE event. The data suggest that RPE events, which are thought to transiently alter the release of dopamine, modulate the vigor of the ensuing movement.