Language Mapping Using Stereo Electroencephalography: A Review and Expert Opinion.

Area of Science:

• Neuroscience
• Neurosurgery
• Epileptology

Background:

• Stereo-electroencephalography (sEEG) with electrical cortical stimulation (ECS) is the gold standard for mapping eloquent cortex, particularly primary areas.
• Higher-order brain areas, like the basal temporal language area (BTLA) in the ventral temporal cortex (VTC), exhibit more complex responses to ECS.
• The ventral language stream, including BTLA, functions as a highly associative cortex, contrasting with the more primary-like dorsal language stream.

Purpose of the Study:

• To review the literature on sEEG-based language mapping, focusing on ECS.
• To establish the validity of sEEG-ECS for mapping indispensable language cortices.
• To highlight the need for research into the mechanisms of ECS in dispensable language cortices (VTC).

Main Methods:

• Review of existing literature on sEEG and ECS for language mapping.
• Analysis of methodological aspects of ECS using sEEG.
• Discussion of network architecture's role in ECS behavioral responses.

Main Results:

• sEEG-ECS is a valid technique for mapping indispensable language cortices in the dorsal language stream.
• There is a gap in understanding the fundamental mechanisms of ECS effects, especially in the VTC's dispensable language cortex.
• Network organization significantly influences the complexity of ECS behavioral responses.

Conclusions:

• sEEG is a valid, safe, and reliable method for defining eloquent language cortices.
• Further research is crucial to understand ECS in associative cortices and network organization.
• Improved understanding could enhance mapping of interindividual variability and predict post-operative deficits.