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Multiscale Investigations of Cortical Processing by Integrating Laminar Polytrodes and Optogenetics with Micro Electrocorticography in Rodents
Published on: May 23, 2025
Mapping the fine structure of cortical activity with different micro-ECoG electrode array geometries
Xi Wang1, C Alexis Gkogkidis, Olga Iljina
1Department of Neurosurgery, Epilepsy Center, Translational Neurotechnology Lab, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, AG Ball, Engelbergerstr. 21 3.0 EG, 79106 Freiburg, Germany. Department of Neurosurgery, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Breisacher Str. 64, 79106 Freiburg, Germany. Laboratory for Biomedical Microtechnology, Department of Microsystems Engineering (IMTEK), University of Freiburg, Georges-Koehler-Allee 102, 79110 Freiburg, Germany. BrainLinks-BrainTools Cluster of Excellence, University of Freiburg, Georges-Koehler-Allee 80, 79110 Freiburg, Germany.
New micro-electrocorticography (µECoG) arrays capture high-frequency neural signals with sub-millimeter precision. Electrode geometry significantly impacts recording performance, crucial for advanced brain mapping and diagnostics.
Area of Science:
- Neuroscience
- Biomedical Engineering
- Signal Processing
Background:
- Innovations in micro-electrocorticography (µECoG) enable electrode arrays with sub-millimeter contact diameters and pitch.
- Understanding the performance of these advanced µECoG arrays is critical for high-resolution neural recording.
Purpose of the Study:
- To investigate the reproducible observation of frequency ranges up to 400 Hz in µECoG recordings.
- To quantify topographical substructure differences across frequency bands and electrode array geometries.
- To assess the influence of cortical vasculature on µECoG signal properties and topographic mapping.
Main Methods:
- Utilized two µECoG electrode arrays with varying contact diameters and inter-contact distances.
- Recorded neural activity from the somatosensory cortex of minipigs up to 400 Hz during acute experiments.
- Analyzed neural data during peripheral electrical stimulation under anesthesia.
Main Results:
- µECoG recordings reliably detected multi-focal cortical somatosensory responses with sub-centimeter separation, unresolvable by conventional ECoG.
- Response patterns varied by stimulation site, intensity, and distinct frequency bands, independent of cortical vasculature.
- Differences in signal strength and signal-to-noise ratios were observed between electrode arrays due to spatial sensitivity.
Conclusions:
- Electrode array geometry significantly influences µECoG recording performance.
- Findings support informed decisions in clinical applications like high-resolution brain mapping, epilepsy diagnostics, and brain-machine interfacing.
