Medical Research Council, Cognition and Brain Sciences Unit, University of Cambridge, 15 Chaucer Road, Cambridge, CB2 7EF, UK.
Neurophys Limited, Cambridge, UK.
Acta Neurochir (Wien). 2021 May;163(5):1299-1309. doi: 10.1007/s00701-020-04646-6. Epub 2020 Nov 22.
Intraoperative functional mapping with direct electrical stimulation during awake surgery for patients with diffuse low-grade glioma has been used in recent years to optimize the balance between surgical resection and quality of life following surgery. Mapping of executive functions is particularly challenging because of their complex nature, with only a handful of reports published so far. Here, we propose the recording of neural activity directly from the surface of the brain using electrocorticography to map executive functions and demonstrate its feasibility and potential utility.
To track a neural signature of executive function, we recorded neural activity using electrocorticography during awake surgery from the frontal cortex of three patients judged to have an appearance of diffuse low-grade glioma. Based on existing functional magnetic resonance imaging (fMRI) evidence from healthy participants for the recruitment of areas associated with executive function with increased task demands, we employed a task difficulty manipulation in two counting tasks performed intraoperatively. Following surgery, the data were extracted and analyzed offline to identify increases in broadband high-gamma power with increased task difficulty, equivalent to fMRI findings, as a signature of activity related to executive function.
All three patients performed the tasks well. Data were recorded from five electrode strips, resulting in data from 15 channels overall. Eleven out of the 15 channels (73.3%) showed significant increases in high-gamma power with increased task difficulty, 26.6% of the channels (4/15) showed no change in power, and none of the channels showed power decrease. High-gamma power increases with increased task difficulty were more likely in areas that are within the canonical frontoparietal network template.
These results are the first step toward developing electrocorticography as a tool for mapping of executive function complementarily to direct electrical stimulation to guide resection. Further studies are required to establish this approach for clinical use.
近年来，在清醒开颅手术中，通过直接电刺激对弥漫性低级别胶质瘤患者进行术中功能定位，以优化手术切除与术后生活质量之间的平衡。由于执行功能的复杂性，目前仅有少数报道对其进行了映射。在此，我们提出使用皮质脑电图直接记录大脑表面的神经活动来映射执行功能，并证明其可行性和潜在的应用价值。
为了追踪执行功能的神经特征，我们在 3 名被判断为患有弥漫性低级别胶质瘤的患者的额皮质区，在清醒开颅手术期间使用皮质脑电图记录神经活动。基于健康参与者的现有功能磁共振成像（fMRI）证据，我们采用了两种术中计数任务的任务难度操作来募集与执行功能相关的区域。术后，我们对数据进行离线提取和分析，以识别出随着任务难度的增加而增加的宽带高伽马功率，这与 fMRI 发现一致，是与执行功能相关的活动的特征。
所有 3 名患者都很好地完成了任务。从 5 个电极条中记录数据，总共得到 15 个通道的数据。15 个通道中有 11 个（73.3%）随着任务难度的增加显示出高伽马功率的显著增加，26.6%的通道（4/15）的功率没有变化，没有一个通道的功率下降。随着任务难度的增加，高伽马功率的增加更有可能发生在符合经典额顶叶网络模板的区域。
这些结果是朝着开发皮质脑电图作为补充直接电刺激以指导切除的执行功能映射工具迈出的第一步。需要进一步的研究来建立这种方法的临床应用。
