In one SEEG patient, 2 mA pulses preserved most 1 mA N1 responses and added farther responders

We compared expert-checked early (N1) responses to single-pulse electrical stimulation at 1 mA and 2 mA in one patient with stereo-electroencephalography (SEEG). The analysis used 22 stimulation pairs common to runs 031031 and 031053 in sub-STREEF08, OpenNeuro ds005448, and excluded stimulated contacts. The 22 pairs had 112 N1 responses at 1 mA and 290 at 2 mA; 110 of the 112 responses at 1 mA were also present at 2 mA, while 180 responses were new and 2 were lost. Seventeen pairs had more responses at 2 mA, none had fewer, and five were equal (exact sign test p = 1.5e-5). Response rates rose at 10–20 mm (0.21 to 0.55) and 20–30 mm (0.01 to 0.12). New 2 mA responders were farther from the stimulated pair than shared responders (median 15.6 vs 12.1 mm, rank-sum p = 2e-11); the farthest response was 22 mm at 1 mA and 35 mm at 2 mA. Among 110 shared responders, amplitude increased (median 2 mA/1 mA ratio 2.26; Spearman 0.71), while latency changed little (median absolute difference 1.7 ms; Spearman 0.74). Map agreement was above a distance-matched null (median kappa 0.43 vs 0.17; p = 8e-5), with low kappa largely reflecting the larger 2 mA map. These findings suggest that, for this patient and these currents, the 1 mA map was nearly a subset of the 2 mA map. The study includes one patient at one center; current is confounded with run order and time, expert labels may depend on signal-to-noise ratio, experts may have seen both runs, and only five pulses per direction per pair were delivered. No raw signals were read.

stereo-electroencephalography · single-pulse electrical stimulation · N1 response · intracranial EEG · current intensity · brain connectivity