Fig. 2: Cells that encode the arrangement and segmentation of phonemes into distinct syllables.
From: Single-neuronal elements of speech production in humans
a, Peri-event time histograms were constructed by aligning the APs of each neuron to word onset. Data are presented as mean (line) values ± s.e.m. (shade). Examples of two representative neurons which selectively changed their activity to specific planned syllables. Inset, spike waveform morphology and scale bar (0.5 ms). b, Scatter plots of D2 values (the degree to which specific features explained neuronal response, n = 272 units) in relation to planned phonemes, syllables and morphemes. c, Average z-scored firing rates as a function of the Hamming distance between the preferred syllabic composition and all other compositions of the neuron. Data are presented as mean (line) values ± s.e.m. (shade). d, Decoding performance for planned syllables. The orange points provide the sampled distribution for the classifier’s ROC-AUC values (n = 50 random test/train splits; P = 7.1 × 10−18 two-sided Mann–Whitney U-test). Data are presented as mean ± s.d. e, To evaluate the selectivity of neurons to specific syllables, their activities were further compared for words that contained the preferred syllable of each neuron (that is, the syllable to which they responded most strongly; green) to (i) words that contained one or more of same individual phonemes but not necessarily their preferred syllable, (ii) words that contained different phonemes and syllables, (iii) words that contained the same phonemes but divided across different syllables and (iv) words that contained the same phonemes in a syllable but in different order (grey). Neuronal activities across all comparisons (to green points) were significant (n = 113; P = 6.2 × 10−20, 8.8 × 10−20, 4.2 × 10−20 and 1.4 × 10−20, for the comparisons above, respectively; two-sided Wilcoxon signed-rank test). Data are presented as mean (dot) values ± s.e.m.
