Sentence-offset high-gamma decreases were consistent, while onset-versus-sustained indices were unreliable in one SEEG patient

We analyzed public SEEG data from OpenNeuro ds004993, sub-W2: 101 sentence trials and 98 adjacent bipolar pairs. High-gamma activity (70–150 Hz) increased significantly during sentences in 30 pairs (BH-FDR q < 0.05). An onset index compared the response at 0.05–0.40 s with the response from 0.60 s to sentence offset. Its odd/even-trial split-half correlation was not significant (Spearman rho = 0.29, p = 0.060). Among 13 temporal pairs, the index had no predicted posterior gradient; the observed correlation had the opposite sign (rho = +0.58, one-sided p = 0.98). High-gamma decreased after sentence offset in all 30 responsive pairs (mean decrease = 0.14 z, p = 0.0001), and this decrease was not larger in sustained pairs (p = 0.77). Most pairs had a larger late than early response (median onset index = -0.17). These results describe one patient, whose sampled sites were mostly superior temporal sulcus and middle temporal gyrus, with no Heschl's gyrus contacts; bipolar pairs sharing contacts are not independent. A time-base error was corrected before the reported analysis: the decimated signal rate was 102.4 Hz, not 100 Hz.

stereo-EEG · high-gamma activity · speech processing · sentence offset · onset response · sustained response · OpenNeuro