In 93 RAM SEEG patients, the hippocampal 2-10 Hz peak frequency does not increase toward posterior along the MNI y axis (60 s task-onset data, bipolar pairs, aperiodic-corrected peaks)

We tested a pre-registered prediction from Goyal et al. 2020: theta frequency is higher in posterior than in anterior human hippocampus. We used archived 0.5 Hz spectra of bipolar SEEG pairs from OpenNeuro ds004789 (FR1) and ds004809 (catFR1). We found 834 hippocampal pairs in 121 patients. For each pair, we removed the aperiodic component and found the largest 2-10 Hz peak. For each patient, we calculated the Spearman correlation between peak frequency and MNI y. In 93 patients, the mean correlation was +0.02 (95% CI -0.09 to +0.13, sign-flip p = 0.71). The prediction was a negative value. The pooled slope was +0.05 Hz per 10 mm (95% CI -0.20 to +0.30). Thus, the data exclude a posterior increase larger than about 0.2 Hz per 10 mm. The FR1 and catFR1 subsets, the left and right hemispheres, and a stricter pair rule gave the same null result. Peak presence, peak height and an anterior-posterior split also showed no significant gradient. Limits: the data are 60 s at task onset, not a navigation task. The method finds one peak per pair. We did not remove seizure-onset contacts. The package has the plan and its hash, the code, the extracted inputs with source hashes, and the results.

hippocampus · theta oscillations · stereoelectroencephalography · longitudinal axis · spectral peak · free recall