Article Figures & Data
Figures
- Figure 1.
Behavioral results. A, Spontaneous speech (overt narration). Normalized mean (solid line) and variance (dashed lines) of the EMG power spectrum with the 1/f trend regressed out are shown. Inset, the original individual spectra (n = 7) are displayed for reference. The arrowhead indicates the mean rate of spontaneous syllable (/pa/) repetition. B, Syllable production. The gray box represents the mean (± SD; n = 11) /pa/ syllable rate in spontaneous production. For the reproduction experiment, the black boxes illustrate the actual reproduction frequencies of /pa/ syllables (mean ± SD; n = 11) as a function of the target frequencies (0.8, 1.1, 1.5, 2, 2.8, 3.7, and 5). The dashed diagonal line indicates ideal compliance with the target rate.
- Figure 2.
Sensor-level and source-level results. A, On the MEG helmet, EMG-MEG coherence was detected bilaterally above the lateral SMC, as displayed for one subject. Coherence spectra of the highlighted left (L) and right (R) hemisphere sensors show, in this individual, a maximum at the fundamental (/pa/ reproduction rate) coherence frequency over the left SMC and maxima at both the fundamental and its harmonic frequency over the right SMC. B, The ventral SMC, bilaterally, shows corticomuscular coherence in a group-level statistical map, calculated across all /pa/ reproduction frequencies and contrasted against resting-state data (pairwise t statistics; p < 0.05; Bonferroni corrected; n = 10). The color bar indicates t score.
- Figure 3.
Speech rate and corticomuscular coherence. A, Bell-shaped profile of the normalized peak coherence values (mean ± SEM) for each actual /pa/ reproduction frequency (mean ± SEM) in the left and right SMC (normalized to the individual maximum value across target conditions to lend equal weight to all subjects' data). The horizontal lines below the coherence curves denote the mean rate (with 25 and 75% percentiles) of spontaneous /pa/ repetition (triangles) and the mean frequency of the local rhythmic EMG maxima in overt narration (corresponding to the ∼1.5–3.5 Hz concentration) (circles) (see Fig. 1A). B, Significant positive correlation (Spearman's ρ) between the individual spontaneous /pa/ repetition frequency and the /pa/ reproduction frequency at which the corticomuscular coherence was strongest, plotted for each hemisphere (L, left; R, right).
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