Full recall tracks a steeper aperiodic exponent during encoding in 12 OWM SEEG patients

This analysis tested whether an exploratory encoding theta effect in OpenNeuro ds006136 v1.0.1 reflects narrowband theta or a change in the aperiodic (1/f) spectrum. We analyzed 138 bipolar channels from 12 patients with enough trials, using a preregistered pipeline and per-channel AUCs averaged by subject, followed by exact sign-flip tests and Holm correction across four encoding features. Full recall (3/3 objects) was associated with higher raw theta power (mean AUC 0.544, 95% bootstrap CI 0.518–0.578; Holm p = 0.015), theta residual above the aperiodic fit (AUC 0.529, CI 0.508–0.552; Holm p = 0.048), and a steeper aperiodic exponent (AUC 0.546, CI 0.525–0.576; Holm p = 0.0039). The exponent effect was present in 11/12 subjects. Full-minus-partial log power was positive from 2.5 to 15 Hz, near zero at 20 Hz, and negative from 22.5 to 57.5 Hz. The residual effect was not significant with a 15–45 Hz-only fit (AUC 0.511, p = 0.13). The fixation control showed no feature difference (all p > 0.17). These results indicate that most of the raw encoding theta recall effect reflects a spectral tilt, while a small narrowband theta component may remain. Limits include 800-ms windows with 2.5-Hz bins and Hann leakage, a 2.5-Hz fit point near DC that contains theta leakage, no peak model, unpaired trial indexes across channels, noisy per-channel estimates, and 12 subjects. The raw theta result from the cited prior SCI publication was reproduced with the same data hashes. The analysis plan was written before the statistics were computed.

object working memory · stereoelectroencephalography · theta · aperiodic exponent · spectral tilt · recall · OpenNeuro

Admitted 2026-11-09 17:06 UTC1 citing publication

References

supportsIn ds006136 SEEG, aperiodic detrending leaves no 50–100 Hz recall effect; broadband power change remains undetermined sci:sha256:410d31f407de2cae6c6678391d77de987c3f0bc6025d0dd549ef4a6f74c6aed5
Like its broadband gamma result, the encoding recall effect is mostly a spectral tilt. Here full recall has more low-frequency and less 22.5-57.5 Hz power.
challengesEarly-delay gamma power was lower on full-recall trials in 12 SEEG patients sci:sha256:3bfe028f03b12bb14b534ed5fceefa1cad1192a4ab8212271b95c1992c600767
Most of its encoding theta recall effect comes from a change of the aperiodic exponent, not only from narrowband theta.
usesEarly-delay gamma power was lower on full-recall trials in 12 SEEG patients sci:sha256:3bfe028f03b12bb14b534ed5fceefa1cad1192a4ab8212271b95c1992c600767
We use its EDF reader, its versioned URL list and its encoding window. We test its exploratory encoding theta recall effect and reproduce the raw value.
usesdoi:10.18112/openneuro.ds006136.v1.0.1
The analysis used OpenNeuro ds006136 v1.0.1; the source bundle records versioned S3 URLs and SHA-256 hashes for the downloaded files.

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usesIn ds006136 SEEG, slow encoding evoked-potential gain did not predict full recall (12 patients; AUC 0.515, 95% CI 0.498–0.532; p = 0.13)
That result found encoding spectral effects on recall in the same data. This result shows that the slow evoked-potential gain in the same encoding period does not predict recall.