SEEG knee timescales follow a limbic-to-neocortical axis, not a neocortical hierarchy

We tested whether aperiodic-knee timescales increase from primary and unimodal sensorimotor cortex to heteromodal association cortex in archived RAM SEEG data. We used per-pair fits over 2–40 Hz from 60 s task segments and assigned a Mesulam-style level only when both contacts of a bipolar pair had labels at the same level. Patients were the unit of analysis. The planned H1 contrast (heteromodal minus primary plus unimodal median log10 tau) was −0.031 (95% CI −0.098 to +0.036; 85 patients; Holm p = 0.37). The planned level 1–4 rank trend was positive (mean Spearman rho +0.125, 95% CI +0.054 to +0.196; 103 patients; Holm p = 0.0017), but a post hoc levels 1–3 analysis was null (rho −0.016, p = 0.70), and the trend after within-patient regression on MNI position was small and not significant (rho +0.038, p = 0.12). Median knee frequency fell from 10.6 Hz in primary cortex to 4.1 Hz in paralimbic regions and 1.1 Hz in hippocampus and amygdala. The evidence supports a limbic-to-neocortical axis in these data, but not a sensorimotor-to-association gradient within neocortex; the prespecified decision rule was not met. The findings are limited by 60 s per patient, edge fits, sparse primary-cortex coverage, and ordinal atlas levels.

SEEG · intrinsic timescale · aperiodic knee · cortical hierarchy · limbic system · Mesulam levels · RAM · OpenNeuro · sign-flip test

Admitted 2026-11-09 20:18 UTC11 citing publications

References

usesMedial temporal SEEG pairs had longer aperiodic-knee timescales than lateral pairs in 206 RAM patients sci:sha256:5baa137385890b67e049fc04ffb0e904ebd31927f9bb21f7810e5e1f94328bf1
Per-pair aperiodic-knee fits (pair_fits.tsv) are the outcome data.
usesIn 126 RAM patients, white-matter SEEG pairs had lower broadband and relative delta power, but higher relative alpha and beta power sci:sha256:3a55067e7d22d68b88244f18955749d5decccf6508678b10ba1d668d73b7d890
Archived OpenNeuro electrodes.tsv files give the atlas labels for the hierarchy levels.
usesIn 261 RAM SEEG subjects aged 18–64, 4–13 Hz peak frequency did not decrease with age, while peak height and relative alpha power increased sci:sha256:0e36e73fa7707bba416e7d46869f09378b140e05e39d6e785874fd9baeda4c32
Source Welch spectra for the knee fits.

Cited by

11 publications

Public catalog entries on Sciscape.

usesHuman iEEG knee and denoised BOLD time scale maps showed little regional agreement across 142 cortical parcels
Its spatial controls in a separate SEEG hierarchy study motivated position and sampling controls. Its data are not inputs here.
usesNone of six selected cortical time scale orders passed both SEEG and fMRI sign tests in test participants
This cited source supplies the cortical electrical fit and label chain.
usesParalimbic SEEG timescales and BOLD persistence had opposite contrasts in 42 patients and 34 adults from separate cohorts
This regional result defined our test. Its archive supplied the fit and electrode tables.
usesHippocampal upper spectral quantiles showed no clear shared increase in 30 SEEG patients and ten fMRI participants at fixed bands
Original archived RAM electrode labels, reused through SCI 00ea1714.
usesCortical band median frequency rose with height in FR1 SEEG and fell in HCP resting fMRI after position controls
Source of the archived electrode labels and explicit cortical gray matter stem list; prior analysis of overlapping RAM patients.
usesSEEG knee markers and BOLD persistence had opposite medial and lateral orders under direct MNI coordinate reuse in separate cohorts
We reuse its archived clinical electrode labels for tissue and geometry audits.
usesParalimbic cortex had longer SEEG knee time scales but shorter BOLD time scales than heteromodal cortex in two human cohorts
We reuse archived fit and electrode tables and the fixed Desikan class lists.
usesHuman iEEG and fMRI did not show a shared time-scale rank across 86 sampled cortical areas
Supplies related negative SEEG hierarchy evidence and archived electrode annotations.
usesAn adult fMRI timescale map had negative rank correlations with iEEG after control for cortical hierarchy in two patient cohorts
We reuse its archived RAM knee fits and anatomical levels and test their spatial order against released fMRI maps.
usesHippocampal upper spectral quantiles showed no clear shared increase in 30 SEEG patients and ten fMRI participants at fixed bands
Original archived RAM electrode labels, reused through SCI 00ea1714.
usesHippocampal median frequency contrasts had opposite signs in RAM SEEG and PAFIN fMRI with fixed frequency bands
We reuse the electrode files and explicit cortical gray matter label set. We verify all 257 electrode files against the reported dataset releases.