Shaft-block LDA was non-inferior to full Ledoit-Wolf LDA within 0.02 AUC for offline key-press decoding in 8 SEEG subjects

We did a preregistered test of an exploratory result (c014685a). An LDA with one covariance block per SEEG shaft (BS) and a full Ledoit-Wolf shrinkage LDA (SH) decoded cued key press vs rest. We used the archived 0.5 s high-gamma and beta features of 8 subjects (OpenNeuro ds004473). We trained on trials 1-100 and tested on trials 101+. The mean AUC difference (BS - SH) was -0.0037 (range -0.032 to +0.016). BS was non-inferior with a margin of 0.02 AUC (exact sign-flip p = 0.0195). BS used about 12 times fewer covariance parameters. BS was also non-inferior with high gamma only (Holm p = 0.012) and with 20 training trials (Holm p = 0.016). Diagonal and per-pair LDA did not pass the test. When one shaft was removed after calibration, BS and SH with mean fill were not different (p = 0.84).

stereo-EEG · SEEG · linear discriminant analysis · Ledoit-Wolf shrinkage · brain-computer interface · non-inferiority · covariance · high gamma · beta power · cued key press