Extended Data Fig. 9: Decoding Analysis by LFP bands.

Each column recreates the analysis of Fig. 4k (top) and Fig. 4l (bottom), quantifying classifier decoding performance for each word category from bandpower values across channels. Colours indicate distributions for 4 patients. LFP prediction was comparable to that of single units. Frequency bands in the alpha range and above were the strongest predictors for semantic category and part of speech. Decoding accuracy was significantly greater than chance (0.5) for all bands, but overall lower than that of single units. Semantic category prediction performance was highest for gamma, followed by low gamma and alpha bands (delta: mean accuracy = 0.520, 72.9% significant categories; theta: mean accuracy = 0.536, 81.3% significant categories; alpha: mean accuracy = 0.555, 77.1% significant categories; beta: mean accuracy = 0.517, 85.4% significant categories; low gamma: mean accuracy = 0.564, 85.4% significant categories; gamma, mean accuracy = 0.572, 85.4% significant categories). Part of speech prediction performance was also significant, though modestly lower than that of semantic category prediction, mirroring results of the single unit analysis. Decoding accuracy was highest for alpha power, followed by gamma and low gamma bands (delta: mean accuracy = 0.515, 58.3% significant categories; theta: mean accuracy = 0.523, 60.0% significant categories; alpha: mean accuracy = 0.564, 60.0% significant categories; beta: mean accuracy = 0.473, 68.3% significant categories; low gamma: mean accuracy = 0.535, 70.0% significant categories; gamma, mean accuracy = 0.536, 71.7% significant categories).