Reward positivity (RewP) is an event-related brain potential component that emerges ∼250–350 ms after receiving reward-related feedback stimuli and is believed to be important for reinforcement learning and reward processing. Although numerous localization studies have indicated that the anterior cingulate cortex (ACC) is the neural generator of this component, other studies have identified sources outside of the ACC, fuelling a debate about its origin. Because the results of EEG and magnetoencephalography source-localization studies are severely limited by the inverse problem, we addressed this question by leveraging the high spatial and temporal resolution of intracranial EEG. We predicted that we would identify a neural generator of rthe RewP in the caudal ACC. We recorded intracranial EEG in 19 patients with refractory epilepsy who underwent invasive video-EEG monitoring at Ghent University Hospital, Belgium. Participants engaged in the virtual T-maze task, a trial-and-error task known to elicit a canonical RewP, while scalp and intracranial EEG were recorded simultaneously. The RewP was identified using a difference wave approach for both scalp and intracranial EEG. The data were aggregated across participants to create a virtual ‘meta-participant’ that contained all the recorded intracranial event-related brain potentials with respect to their intracranial contact locations. We used both hypothesis-driven (focused on ACC) and exploratory (whole-brain analysis) approaches to segment the brain into regions of interest. For each region of interest, we evaluated the degree to which the time course of the absolute current density (ACD) activity mirrored the time course of the RewP, and we confirmed the statistical significance of the results using permutation analysis. The grand average waveform of the scalp data revealed a RewP at 309 ms after reward feedback with a frontocentral scalp distribution, consistent with the identification of this component as the RewP. The meta-participant contained intracranial event-related brain potentials recorded from 582 intracranial contacts in total. The ACD activity of the aggregated intracranial event-related brain potentials was most similar to the RewP in the left caudal ACC, left dorsolateral prefrontal cortex, left frontomedial cortex and left white matter, with the highest score attributed to caudal ACC, as predicted. To our knowledge, this is the first study to use intracranial EEG aggregated across multiple human epilepsy patients and current source density analysis to identify the neural generator(s) of the RewP. These results provide direct evidence that the ACC is a neural generator of the RewP.

中文翻译：

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揭开奖励阳性的起源：一项与人类颅内事件相关的脑电位研究


奖励积极性 （RewP） 是一种与事件相关的大脑潜力成分，在接受与奖励相关的反馈刺激后 ∼250-350 毫秒出现，被认为对强化学习和奖励处理很重要。尽管许多定位研究表明前扣带皮层 （ACC） 是该成分的神经生成器，但其他研究已经确定了 ACC 之外的来源，从而引发了关于其起源的争论。由于 EEG 和脑磁图来源定位研究的结果受到逆问题的严重限制，我们通过利用颅内 EEG 的高空间和时间分辨率来解决这个问题。我们预测我们将在尾部 ACC 中识别 rthe RewP 的神经生成器。我们记录了 19 例在比利时根特大学医院接受侵入性视频脑电图监测的难治性癫痫患者的颅内脑电图。参与者参与了虚拟 T 迷宫任务，这是一项已知的试错任务，可以引发经典的 RewP，同时同时记录头皮和颅内脑电图。使用头皮和颅内 EEG 的差分波方法确定 RewP。数据在参与者之间汇总，以创建一个虚拟的“元参与者”，其中包含所有记录的与颅内事件相关的脑电位，以及他们的颅内接触位置。我们使用假设驱动（专注于 ACC）和探索性（全脑分析）方法将大脑分割成感兴趣的区域。对于每个感兴趣的区域，我们评估了绝对电流密度 （ACD） 活动的时间进程与 RewP 时间进程的程度，并使用排列分析证实了结果的统计显着性。 头皮数据的大平均波形显示，奖励反馈后 309 ms 的 RewP 具有额中央头皮分布，与该组件作为 RewP 的识别一致。meta 参与者包含总共 582 次颅内接触记录的颅内事件相关脑电位。正如预测的那样，聚集的颅内事件相关脑电位的 ACD 活性与左尾部 ACC 、 左侧背外侧前额叶皮层 、 左侧额内侧皮层和左白质的 RewP 最相似，其中尾部 ACC 得分最高。据我们所知，这是第一项使用跨多个人类癫痫患者汇总的颅内脑电图和电流源密度分析来识别 RewP 的神经发生器的研究。这些结果提供了直接证据，证明 ACC 是 RewP 的神经生成器。