Intracranial recordings in human subjects provide a unique, fine-grained temporal and spatial resolution inaccessible to conventional non-invasive methods. A prominent signal in these recordings is broadband high-frequency activity (approx. 70–150 Hz), generally considered to reflect neuronal excitation. Here we explored the use of this broadband signal to track, on a single-trial basis, the temporal and spatial distribution of task-engaged areas involved in decision-making. We additionally focused on the alpha rhythm (8–14 Hz), thought to regulate the (dis)engagement of neuronal populations based on task demands. Using these signals, we characterized activity across cortex using intracranial recordings in patients with intractable epilepsy performing the Multi-Source Interference Task, a Stroop-like decision-making paradigm. We analyzed recordings both from grid electrodes placed over cortical areas including frontotemporal and parietal cortex, and depth electrodes in prefrontal regions, including cingulate cortex. We found a widespread negative relationship between alpha power and broadband activity, substantiating the gating role of alpha in regions beyond sensory/motor cortex. Combined, these signals reflect the spatio-temporal pattern of task-engagement, with alpha decrease signifying task-involved regions and broadband increase temporally locking to specific task aspects, distributed over cortical sites. We report sites that only respond to stimulus presentation or to the decision report and, interestingly, sites that reflect the time-on-task. The latter predict the subject’s reaction times on a trial-by-trial basis. A smaller subset of sites showed modulation with task condition. Taken together, alpha and broadband signals allow tracking of neuronal population dynamics across cortex on a fine temporal and spatial scale.

中文翻译：

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Alpha 和宽带高频活动跟踪任务动态并预测受控决策中的性能

人类受试者的颅内记录提供了传统非侵入性方法无法获得的独特、细粒度的时间和空间分辨率。这些记录中的一个突出信号是宽带高频活动（约 70–150 Hz），通常被认为反映了神经元兴奋。在这里，我们探索了使用这种宽带信号在单次试验的基础上跟踪参与决策的任务参与区域的时间和空间分布。我们还关注 alpha 节律 (8–14 Hz)，认为它可以根据任务需求调节神经元群的（脱离）参与。使用这些信号，我们使用顽固性癫痫患者执行多源干扰任务（一种类似 Stroop 的决策范式）的颅内记录来表征整个皮质的活动。我们分析了放置在皮质区域（包括额颞叶和顶叶皮质）上的网格电极和前额区域深度电极（包括扣带回皮质）的记录。我们发现 alpha 功率和宽带活动之间存在广泛的负相关关系，证实了 alpha 在感觉/运动皮层以外区域的门控作用。结合起来，这些信号反映了任务参与的时空模式，alpha 减少表示涉及任务的区域，宽带增加暂时锁定到特定任务方面，分布在皮层站点。我们报告仅响应刺激演示或决策报告的站点，有趣的是，还报告了反映任务完成时间的站点。后者在逐个试验的基础上预测受试者的反应时间。一小部分网站显示了任务条件下的调制。总之，alpha 和宽带信号允许在精细的时间和空间尺度上跟踪整个皮层的神经元种群动态。