Median high-gamma recovery was 20–120 ms and shortened with distance after single pulses in five SEEG patients; broadband voltage recovered within 10 ms at most channels

We measured how long a single SEEG stimulation pulse disturbs the recorded signal. We used 5 patients from OpenNeuro ds005448 (40 sites, 160 pulses, 2809 bipolar and 3216 common-average channel-site pairs). For each channel, the recovery time is the last 10 ms bin after the pulse where the signal is above the 99.5th percentile of a no-pulse sham window. Causal 70-150 Hz (high gamma) power had a median recovery time of 0.10 s at bipolar channels less than 15 mm from the stimulated pair and 0.02 s at 50 mm or more. With common-average reference, the times were 0.12 s and 0.06 s. Broadband voltage recovered within 0.01 s at most channels. In all 5 patients, recovery time decreased with distance for all features and references (one-sided Wilcoxon p = 0.031). Approximately 30% of bipolar high-gamma channels stayed above the threshold for more than 0.5 s, compared with approximately 10% in sham. The method does not separate artefact from evoked physiology. For a closed-loop BCI, these results support a high-gamma blanking window of approximately 100 ms near the stimulated site and bipolar referencing.

stereo-EEG · SEEG · single-pulse electrical stimulation · high gamma · signal recovery · common-average reference · bipolar reference · closed-loop brain-computer interface