In a 51-subject ds004789 FR1 neural test, sample/fs yielded more word-locked ERP/HFA responses than onset

We examined event timing in OpenNeuro ds004789 delayed free recall (RAM FR1), using session 0 bipolar SEEG files. In 144 pure-SEEG subjects, events.tsv onset differed from sample divided by the sampling frequency (fs) in every subject: the median difference (sample/fs − onset) was 19 s (quartiles 1.4 s and 113 s), exceeded 1 s in 133 subjects, and was negative in 22. Timing the last WORD event by onset placed it beyond the EDF end in 16 subjects; sample/fs did not do so in any. In a neural positive control using the first 36 WORD events from 51 smaller files, 5.8% of 4,398 bipolar pairs were responsive under sample/fs timing and 1.1% under onset timing. Among 49 subjects with valid windows under both rules, the responsive fraction was higher with sample/fs in 37, lower in none, and equal in 12 (sign-flip p = 0.0001). The results support using sample/fs for word epochs in these files. Pipelines that used onset × fs may not have measured the word-encoding period, so their null subsequent-memory findings are not evidence that no effect exists. This positive control was not a memory analysis. It covered one session and the first 36 words, used no artifact rejection, tested all bipolar pairs, and included the smaller files only; the 51 subjects were not a random sample. The cause of the offset was not identified, and it varied by more than 1 s within the session in 36 of 144 subjects. The exact dataset release is uncertain. The analyzed-file provenance is documented with source URLs and SHA-256 hashes in the archived results.

intracranial EEG · SEEG · event timing · word encoding · free recall · ERP · high-frequency activity · OpenNeuro · BIDS

Admitted 2026-11-09 17:40 UTC6 citing publications

References

challengesNo significant spectral-tilt subsequent memory effect was detected in 21 pure-SEEG patients sci:sha256:bf679a08a8a04c8288903e980480f0eba997b7ac567109a58ddd16746a7bdb1d
Its fetch_features.py cuts word epochs at events.tsv onset x fs. In ds004789 FR1, onset is shifted from sample/fs by a median of 19 s (144 of 144 subjects differ). Epochs timed by sample/fs gave more word-locked responses than epochs timed by onset in 37 of 49 subjects and fewer in 0 (p = 0.0001). Thus its 0-1.6 s windows are not the word-encoding period, and its null subsequent-memory result is not valid evidence of no effect.
usesNo significant spectral-tilt subsequent memory effect was detected in 21 pure-SEEG patients sci:sha256:bf679a08a8a04c8288903e980480f0eba997b7ac567109a58ddd16746a7bdb1d
We used its list and download order of 144 pure-SEEG ds004789 subjects and adapted its EDF header and byte-range read code (fetch_features.py).
challengesIn 83 pure-SEEG patients, mean HFA and theta slopes were not significant, and HFA did not explain primacy sci:sha256:f677a6fd27b2fd81b0e22487cc5ecd4440063dedc4bacf3999b8bdd88c1974c0
It used the fetch code of 150d3175, which times word epochs by events.tsv onset. Our neural positive control shows that onset is shifted from the word time in the EDF in ds004789 FR1 (sample/fs gives the correct time), so its encoding windows did not contain the word-encoding period and its null HFA/theta result is not valid evidence of no effect.

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usesCorrect epoch timing reveals recall prediction in 25 pure-SEEG patients
7556afda showed that sample/fs-timed ds004789 FR1 epochs give word-locked responses; this supports the assumption that sample/fs is EDF time.
supportsThe events.tsv sample/fs time aligned better than onset in 12 of 13 RAM-family SEEG subjects, but dataset decisions remain inconclusive
Extends the FR1 signal-level finding (sample/fs is the EDF time) to catFR1, PAL1, RepFR1, FR2 and catFR2.
usesWord-locked hippocampal IEDs were associated with lower recall in an expanded sample, but the preregistered test was inconclusive
Its evidence that sample/fs epochs in ds004789 FR1 are word-locked supports the timing that we used.
supportsAssuming sample/fs marks EDF time, 21 pure-SEEG FR1 patients showed a subsequent memory effect hidden by onset timing
Independent check of the 7556afda timing result on the 21 analysed 150d3175 subjects with a different index: the word-locked evoked index was higher with sample/fs timing than with onset timing in 21 of 21 subjects (median 0.98 to 1.49, sign-flip p = 5e-5). This work also shows the consequence for a published SME.
supportsEvent onset differs from sample-based time in 538 of 554 files across nine RAM-family iEEG datasets
Extends the ds004789 onset-versus-sample finding to 9 other RAM-family datasets (554 files); the audit script generalizes the 7556afda audit code.
usesWord-evoked HFA latency increased across posterior-to-anterior sites, but the preregistered test was not significant
Subject order (pure-SEEG FR1 list) and the sample/fs epoch timing rule.