In 43 Hz alternating-polarity SEEG trains, the polarity-invariant component did not decline more than the polarity-flipping component

We tested whether the polarity-invariant pulse-locked SEEG component (S), treated as a possible neural response, declined during 43 Hz alternating-polarity bipolar stimulation while the polarity-flipping component (D), treated as artifact, stayed constant. In 11 usable trains from 7 patients in OpenNeuro ds006519 v1.0.0, the primary contrast (median log last/first ratio for S minus that for D) was +0.034 (ratio 1.035; 5/7 patients negative; exact two-sided sign-flip p = 0.80). S declined by about 5–10% (mean log ratio -0.055; p = 0.094), and D also declined (mean -0.090; p = 0.28). The data do not show that S behaves differently from D, and do not establish that S is neural or artifact. The pooled time course showed a roughly 10% decline in S with D nearly stable, while D declined more than S in two patients. Limits include 7 patients at one centre, a 2–15 ms response window and grid-based pulse polarity procedure chosen for this analysis, S near the noise floor in many channels, and unmodelled amplifier saturation.

stereo-EEG · intracranial EEG · cortical stimulation · alternating polarity · pulse-locked response · artifact · neural adaptation · OpenNeuro ds006519