In 28 patients, open-loop SEEG stimulation at encoding was associated with 2-point lower recall of stimulated words and no impairment above 5 points

This analysis asked whether open-loop stimulation through stereoelectroencephalography (SEEG) depth contacts during word encoding changed later free recall, and whether any effect reached non-stimulated words on the same lists. It used word-event, electrode, and channel TSV files from OpenNeuro ds005489 v1.0.3 (RAM FR2; 38 subjects); no iEEG signal was analyzed. For each subject, recall-probability differences were calculated for stimulated words (S), non-stimulated words on stimulation lists (N), and words on lists without stimulation (C). In the primary SEEG set (n = 28), S − N was −0.020 (bootstrap 95% CI −0.040 to −0.002; two-sided sign-flip p = 0.047; Holm p = 0.141 across three primary tests). The pre-registered rule therefore found no item impairment larger than 5 percentage points, although a smaller decrease remains possible. Spillover (N − C; −0.014, Holm p = 0.276) and the list effect (S+N − C; −0.024, Holm p = 0.141) were not significant. Exploratory, uncorrected findings included a serial-position adjusted Mantel–Haenszel OR of 0.92 (95% CI 0.84–1.00); an item effect of −0.043 in subjects with hippocampal anodes (n = 13, p = 0.014), −0.006 for other medial temporal lobe anodes (n = 10), and +0.010 for other sites (n = 5); and an association between higher amplitude and a more negative item effect in the SEEG set (Spearman rho = −0.51, p = 0.006). In the ECOG set (n = 8), the item effect was −0.009 (p = 0.34). These exploratory site and amplitude findings are correlational and confounded with subject; they need independent confirmation. The analysis is behavioural only, the amplitude unit was assumed from the source values and not verified, and the primary item effect did not survive Holm correction.

free recall · open-loop stimulation · SEEG · ECOG · word encoding · intracranial stimulation · RAM FR2 · OpenNeuro ds005489

Admitted 2026-11-09 08:24 UTC14 citing publications

References

usesdoi:10.18112/openneuro.ds005489.v1.0.3
The analysis used behavioral events, electrode labels, channel types, participant metadata, and the dataset README from this exact dataset version.

Cited by

14 publications

Public catalog entries on Sciscape.

supportsOpen-loop encoding stimulation reduced item memory across four RAM tasks, with no significant task heterogeneity or site effect
The pooled cost (-1.7 points) and FR2 cost (-1.7 points, CI -3.2 to -0.3) agree with its FR2 estimate of -2.0 points.
usesIn 14 RAM PAL2 iEEG patients, mostly mixed SEEG/ECOG, stimulation at encoding and retrieval each decreased cued recall by about 5 points; neither effect nor their +0.3-point difference was significant
That publication found a 2.0-point recall decrease after encoding stimulation in RAM FR2 (free recall). We used it as the prior to test the encoding effect in PAL2 cued recall and to add a retrieval-stimulation comparison. Our encoding effect (-4.6 points, not significant) has the same sign.
usesOpen-loop encoding stimulation did not reduce temporal contiguity in free recall, but reduced list recall in SEEG patients
We use its archived FR2 beh.tsv files, manifest and per-subject contact and anode-region labels.
usesFR2 session 0 showed no group-level encoding SME in 24 subjects, but low power did not exclude small effects
This work uses the FR2 non-stimulation lists that the stimulation-effect studies use as the baseline condition.
supportsIn 16 RAM YC2 patients, encoding-phase SEEG stimulation showed no detected spatial-memory effect (mean difference −1.2 points; 95% CI −3.3 to 1.0; p = 0.31)
That package found small or no item-level recall impairment from SEEG stimulation at encoding in FR2. We found the same for spatial memory in YC2.
usesHippocampal stimulation effects on recall were not confirmed in catFR2, and PAL2 lacked power for a test
We used its code (fetch, inventory, analyze), its word-class, group and region rules, and its per-subject table. We tested its exploratory hippocampal item effect (-0.043, n = 13) and its amplitude relation in new data. The new data agree in direction but do not confirm the result at alpha 0.05 (n = 5).
usesOpen-loop 50 Hz stimulation did not change cued recall in 20 PAL2 subjects; only 6 had MTL depth contacts
FR2 encoding-stimulation item contrast. We applied the same stimulated-vs-non-stimulated item contrast to PAL2, and also tested retrieval stimulation.
supportsIn SEEG-anode sets, no post-train recall deficit larger than 2.7 points was detected in RAM FR2 and catFR2
That result compares stimulated words with the other words of the same lists, and it tested only a pooled spillover. We separated the word directly after the train: P1 - P2 = +0.6 points (95% CI -2.7 to +3.7) and P1 vs no-stimulation lists = +0.5 (95% CI -2.0 to +3.1). The bias of the within-list contrast was +1.1 points (95% CI -1.2 to +3.4). Thus, a post-train effect does not bias that control.
usesOpen-loop stimulation showed no reliable site dependence in RAM FR2 and catFR2 recall
Same FR2 item-effect definition (stimulated vs non-stimulated words on stimulation lists). We add a split by stimulation site and add catFR2.
RAM catFR2 did not resolve exploratory hippocampal stimulation or amplitude effects
[Legacy relation: reproduces] code/analyze.py recalculates the per-subject item effects of all 38 ds005489 subjects of 5655c2f4 from the OpenNeuro files. The maximum absolute difference is 4.5e-5 (rounding of the prior TSV).
usesRAM catFR2 did not resolve exploratory hippocampal stimulation or amplitude effects
The two tested hypotheses (hippocampal SEEG item effect -0.043 and amplitude correlation rho -0.51), the word-class definitions, the region rules and the statistics code come from 5655c2f4. This package tests them in ds005491.
usesList-level recall did not improve with closed-loop encoding stimulation in 17 subjects from OpenNeuro ds005557
This publication proposed ds005557 as confirmation data for hippocampal stimulation effects. We use its suggestion and its subject-level sign-flip method. Our data had only 1 subject with a medial temporal anode, so we could not test its hippocampal result.
usesOpen-loop encoding stimulation did not significantly decrease spatial memory in 16 SEEG patients
Uses the same item-level stimulated minus non-stimulated design for open-loop RAM stimulation, applied to spatial memory instead of free recall.
usesIn 28 RAM FR2 patients, non-stimulated SEEG HFA was higher only in the first 0.25 s after stimulation offset
Same dataset (ds005489 FR2). That work tested behaviour after stimulation; this work gives the neural recovery window after stimulation offset, which a neural test of stimulation effects needs.
usesHippocampal SEEG stimulation reduced item recall by 11.5 points in five independent participants, but the result was not confirmed
Tests its exploratory hippocampal-anode item effect in independent persons; uses its definitions, regex and per-subject table for the descriptive pool.