Department of Neurological Surgery, Columbia University Medical Center, New York, NY, USA.
Translational Neuroscience Division, Center for Biomedical Imaging and Neuromodulation, Nathan Kline Institute, Orangeburg, NY, USA.
Psychophysiology. 2022 May;59(5):e13901. doi: 10.1111/psyp.13901. Epub 2021 Jul 20.
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.
颅内记录为人类提供了一种独特的、高时间和空间分辨率的方法，这是传统的非侵入性方法无法实现的。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的兴奋。在这里，我们探索了使用这种宽带信号来跟踪涉及决策的任务参与区域的时间和空间分布，基于单次试验的基础上。我们还特别关注 alpha 节律（8-14 Hz），它被认为根据任务需求来调节神经元群体的（不）参与。使用这些信号，我们使用颅内记录对难治性癫痫患者进行了多源干扰任务（一种类似斯特鲁普的决策范式），分析了放置在额颞叶和顶叶皮层以及前额叶区域的深部电极上的网格电极记录的皮层活动。我们发现 alpha 功率和宽带活动之间存在广泛的负相关，这证实了 alpha 在感觉/运动皮层之外的区域中的门控作用。这两种信号结合起来反映了任务参与的时空模式，alpha 减少表示涉及任务的区域，宽带增加在时间上与特定的任务方面锁定，分布在皮质部位。我们报告了仅对刺激呈现或决策报告有反应的部位，有趣的是，还有反映任务时间的部位。后者可以根据每个试验的基础预测受试者的反应时间。较小的一部分部位表现出与任务条件的调制。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群体动力学。
