Extended Data Fig. 6: Phonetic representations of words during speech perception and the comparison of speaking to listening.
From: Single-neuronal elements of speech production in humans
a. Left, Venn diagrams of neurons that selectively changed their activity to specific phonemes during word planning (−500:0 ms from word utterance onset) and perception (0:500 ms from word utterance onset). Right, average z-scored firing rate for selective neurons during word planning (black) and perception (grey) as a function of the Hamming distance. Here, the Hamming distance was based on the neurons’ preferred phonetic compositions during production and compared for the same neurons during perception. Data are presented as mean (line) values ± standard error of the mean (shade). b. Left, classifier decoding performances for selective neurons during word planning. The points provide the sampled distribution for the classifier’s ROC-AUC values (black) compared to random chance (grey; n = 50 random test/train splits; p = 7.1×10−18, two-sided Mann–Whitney U-test). Middle, decoding performance for selective neurons during perception (n = 50 random test/train splits; 7.1×10−18, two-sided Mann–Whitney U-test). Right, word planning-perception model-switch decoding performances for selective neurons. Here, models were trained on neural data for specific phonemes during planning and then used to decode those same phonemes during perception (n = 50 random test/train splits; p > 0.05, two-sided Mann–Whitney U-test; Methods). The boundaries and midline of the boxplots represent the 25th and 75th percentiles and the median, respectively. c. Peak decoding performance for phonemes, syllables and morphemes as a function of time from perceived word onset. Peak decoding for morphemes was observed significantly later than for phonemes and syllables during perception (n = 50 random test/train splits; two-sided Kruskal–Wallis, H = 14.8, p = 0.00062). Data are presented here as median (dot) values ± bootstrapped standard error of the median.
