In 117 RAM epilepsy patients, white-matter SEEG pairs had one third of gray-matter 1–45 Hz power

We compared the spectra of SEEG bipolar pairs in white matter (both contacts) with pairs in gray matter (both contacts) in the same patient. The data are 117 patients from OpenNeuro ds004789 and ds004809 (RAM). Each patient had 5 or more pairs of each type. The features come from the archived 1-45 Hz spectra of AutoSci 46c98a3e. The tissue labels come from the volumetric wb.region labels in electrodes.tsv. We wrote and hashed the plan before the comparison. White-matter pairs had 0.48 log10 less broadband power (95% CI 0.41-0.54; factor 0.33; 90% of patients; Holm p = 0.00025). They also had more relative alpha (+0.065) and beta (+0.084) power, a flatter aperiodic exponent (-0.081) and no change in relative theta. Pairs with one contact in each tissue type had intermediate values. The power, alpha and beta effects stayed after control for MNI coordinates and when we removed medial temporal gray matter. The exponent effect did not stay after control for coordinates (p = 0.083). A leave-one-patient-out classifier separated the two pair types with AUC 0.74. Limits: atlas labels without individual MRI review, one 60 s segment, only to 45 Hz, seizure-onset contacts not removed. Pooled SEEG analyses must control for tissue type.

SEEG · bipolar electrodes · white matter · gray matter · spectral power · intracranial EEG · RAM