Language areas revisited by principal component analysis of electrical cortical stimulation mapping

Abstract Electrical cortical stimulation (ECS) remains the gold standard for language mapping in neurosurgery; thus, systematic and less invasive language tasks focusing on each language function should be developed. This study aimed to clarify the correlation between anatomy and language function by extracting principal components (PCs) directly related to language function from six tasks. Twelve patients with intractable temporal lobe epilepsy underwent ECS mapping with subdural electrode placement in the language-dominant hemisphere: 313 electrodes (3–48/patient) were confirmed to be located over the language areas by ECS mapping using six language tasks. Three major PCs were delineated; PC1, PC2, and PC3 represented reading, auditory receptive semantic processing, and expressive semantic processing, respectively. Anatomically, PC1 was prominent at the inferior frontal gyrus (IFG, especially pars opercularis), posterior parts of the superior temporal sulcus (STS), middle temporal gyrus (MTG), and inferior temporal gyrus; PC2 at the posterior part of IFG (extended more anteriorly than PC1), posterior superior temporal gyrus (STG), posterior MTG, and anterior ventral temporal cortex (VTC); and PC3 at the broad area including regions of the PC1 and PC2, and supramarginal gyrus (SMG) and VTC. Statistically significant functional differentiation was observed in the posterior language area (between the SMG and posterior STG) and basal temporal language areas (among the anterior, middle, and posterior parts). In conclusion, PC analysis revealed three independent language functions and indicated functional differences within the posterior and basal temporal language areas. Clinically efficient language mapping is expected by task selection, considering PCs and regions. Competing Interest Statement The authors have declared no competing interest. Funding Statement This study was funded by the Grant-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology (MEXT) KAKENHI. RM reports grants from MEXT, KAKENHI 18K19514, 22H04777, 22H02945, 23KK0146, AS reports grants from 19K17033, 22K07537 and AI reports grants from 15H05874. Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics committee/IRB of Kyoto University Hospital gave ethical approval for this work(approval number, C533). I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Data availability statement All data used for the analyses reported in this manuscript are available upon request.