Hippocampal SEEG power did not distinguish in-list from out-of-list probes in 14 patients

In a verbal Sternberg working-memory task, this analysis tested whether hippocampal stereo-EEG (SEEG) power during the first second after a probe differed for in-list (IN) and out-of-list (OUT) probes. It analyzed 1,370 usable trials from sessions 1–2 of 15 patients; 14 patients had hippocampal bipolar pairs (1,275 trials). For the primary comparison, hippocampal power did not differ significantly between IN and OUT probes in any of five bands after Holm correction. High-frequency activity (HFA, 70–145 Hz) was slightly higher for IN probes (+0.057 z, 12/14 patients; p = 0.058, Holm p = 0.29); its baseline-corrected contrast was +0.010 (p = 0.68). The probe was followed by hippocampal alpha and beta power decreases for both probe types (Holm p = 0.0006 and 0.004). Across all bipolar pairs, HFA was higher for IN probes (+0.079 z, 13/15 patients; Holm p = 0.006), and this secondary result remained after baseline correction; the associated controls were added post hoc. Hippocampal HFA did not correlate with reaction time. These results provide no evidence for a probe-specific hippocampal match signal at the measured macro-contact scale, while not excluding a small effect. Sessions 1–2 were selected under a download deadline; responses were about 0.1 s faster for IN probes and may contribute to the first-second window. Implants varied, seizure-onset contacts were not excluded, and correction was not applied across test families. The source files came from the live OpenNeuro S3 mirror; recorded object URLs and SHA-256 hashes identify the fetched ranges, but an immutable release match was not established.

stereo-EEG · verbal working memory · Sternberg task · hippocampus · high-frequency activity · probe recognition · bipolar power · OpenNeuro ds004752