Intracranial Electrode Localization and Brain Mapping Techniques

Intracranial electrode localisation and brain mapping represent pivotal methodologies in both clinical neurosurgery and fundamental neuroscience. By implanting electrodes either on the cortical surface (electrocorticography) or within deep brain structures (stereo-electroencephalography), researchers and clinicians obtain high-resolution temporal and spatial recordings of neural activity. Precise localisation of each contact relative to individual anatomy is essential: it underpins accurate interpretation of electrophysiological data, guides surgical resections in refractory epilepsy and informs models of cognitive function. Modern workflows typically integrate preoperative magnetic resonance imaging with postoperative computed tomography through co-registration algorithms, enabling three-dimensional reconstruction of electrode arrays within a patient-specific anatomical framework. Automated and semi-automated pipelines now streamline segmentation of electrodes, correction for brain shift and labelling against standard atlases. Complementary mapping techniques—such as electrical stimulation mapping, functional connectivity analyses and current source density estimation—further elucidate the relationship between recorded signals and underlying neural generators. Advances in software have reduced manual intervention, minimised localisation errors to submillimetre scales and accelerated processing from days to hours. Collectively, these developments have expanded the global impact of intracranial methodologies, facilitating multi-centre studies, enabling personalised therapeutic strategies and deepening our understanding of human brain function.

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Intracranial Electrode Localization and Brain Mapping Techniques publication trend

The graph below shows the total number of articles in intracranial electrode localization and brain mapping techniques across all publications each year (not limited to Nature Index journals).

Technical terms

Intracranial Electroencephalography (iEEG): Direct recording of electrical activity from implanted electrodes within or on the surface of the brain.

Electrocorticography (ECoG): Recording modality using grids or strips of electrodes placed subdurally on the cortical surface to capture local field potentials.

Stereo-Electroencephalography (sEEG): Technique involving the insertion of depth electrodes into targeted brain regions to record signals from deep cortical and subcortical structures.

Co-registration: Computational alignment of multimodal images (e.g. MRI and CT) into a common coordinate system to localise electrodes relative to anatomy.

Anatomical Labelling: Process of assigning each electrode contact to a specific brain region or atlas parcel based on its spatial coordinates.

Grey Matter Proximity Index: Quantitative measure of the distance between an electrode contact and the nearest cortical grey matter surface.

References

1. SEEG assistant: a 3DSlicer extension to support epilepsy surgery. BMC Bioinformatics (2017).
2. iElectrodes: A Comprehensive Open-Source Toolbox for Depth and Subdural Grid Electrode Localization. Frontiers in Neuroinformatics (2017).
3. LeGUI: A Fast and Accurate Graphical User Interface for Automated Detection and Anatomical Localization of Intracranial Electrodes. Frontiers in Neuroscience (2021).
4. Advances in human intracranial electroencephalography research, guidelines and good practices. NeuroImage (2022).