Intraoperative mapping of executive function using electrocorticography for patients with low-grade gliomas

Yaara Erez, Moataz Assem, Pedro Coelho, Rafael Romero-Garcia, Mallory Owen, Alexa McDonald, Emma Woodberry, Robert C. Morris, Stephen J. Price, John Suckling, John Duncan, Michael G. Hart, Thomas Santarius

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


Background: 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. Methods: 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. Results: 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. Conclusions: 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.

Original languageEnglish
Pages (from-to)1299-1309
Number of pages11
JournalActa Neurochirurgica
Issue number5
StatePublished - May 2021
Externally publishedYes

Bibliographical note

Funding Information:
The Royal Society provided financial support in the form of a Royal Society Dorothy Hodgkin Research Fellowship to YE (DH130100). Cambridge Commonwealth European and International Trust provided financial support in the form of a Yousef Jameel scholarship to MA. Guarantors of Brain provided financial support in the form of a Post-Doctoral Fellowship award to RRG. The National Institute for Health Research (NIHR, UK) provided financial support in the form of a Clinician Scientist Award 35 to SJP (ref: NIHR/CS/009/011). The Brain Tumour Charity provided financial support in the form of a grant award to MGH (ref: RG86218). All the sponsors had no role in the design or conduct of this research.

Publisher Copyright:
© 2020, The Author(s).


  • Awake neurosurgery
  • Brain tumor
  • Electrocorticography (ECOG)
  • Executive function
  • Functional mapping
  • Intraoperative
  • Low-grade glioma
  • Patients


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