During removal of a right parafalcine meningioma, surgeons placed four Layer 7 μECoG arrays, 4,096 electrodes in total, on either side of the central sulcus and recorded somatosensory evoked potentials under 5 contralateral stimulation conditions. Using a 2 MΩ impedance cutoff, 3,739 channels were usable, a 91.3% yield; phase-reversal latencies were 19, 21, 25, 26 and 25 ms, consistent with the standard intraoperative mapping performed in the same operation. The researchers caution that the setup provides dense spatial sampling rather than submillimeter physiological resolution: measured responses were correlated across roughly 3–4 mm of cortex.
Why it matters
Surgeons usually locate the central sulcus with sparse subdural strip electrodes that yield only a handful of points. By covering both sides of the sulcus with 4,096 electrodes, this study renders the polarity reversal as a continuous two-dimensional boundary instead of a jump between two neighboring contacts. Notably, the authors draw their own line: electrode pitch is 400 μm, but measured signals correlated across 3–4 mm, so the gain is in sampling density, not resolution. In the same operation, the automated classification agreed with standard mapping.
