Fig. 4: Comparison of neural signals during attempts to silently say English letters and NATO code words. | Nature Communications

Fig. 4: Comparison of neural signals during attempts to silently say English letters and NATO code words.

From: Generalizable spelling using a speech neuroprosthesis in an individual with severe limb and vocal paralysis

Fig. 4

a Classification accuracy (across n = 10 cross-validation folds) using models trained with HGA+LFS features is significantly higher for NATO code words than for English letters (**P = 1.57 × 10−4, z = 3.78, two-sided Wilcoxon Rank-Sum test). The dotted horizontal line represents chance accuracy. b Nearest-class distance is significantly larger for NATO code words than for letters (boxplots show values across the n = 26 code words or letters; *P = 2.85 × 10−3, z = 2.98, two-sided Wilcoxon Rank-Sum test). In a, b, each data point is plotted as a dot, and each boxplot depicts the median as a center line, quartiles as bottom and top box edges, and the minimum and maximum values as whiskers (except for data points that are 1.5 times the interquartile range). c The nearest-class distance is greater for the majority of code words than for the corresponding letters. In b and c, nearest-class distances are computed as the Frobenius norm between trial-averaged HGA+LFS features. Data to recreate all panels are provided as a Source Data file.

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