Figure 3. Effects of pre-load on the entrainment of left masseteric EMG to 20-Hz stimulation of an incisor. The data displayed in this Fig. come from the six participants who had significant coherence values at all pre-loads when 20-Hz stimulation was applied (n = 6). (A) Average normalized gain response ± SEM (red) and average coherence Z-scores plotted against pre-load. The strength of correlation is expressed alongside the respective plot. Hyperbolic curves were fitted. (B) Coherence data presented in (A). (black) Compared with (i) the tooth movement/force relationship presented in Fig. 3 in Parfitt (1960); and (ii) the periodontal mechanoreceptor steady-state response/force relationship presented in Fig. 1b in Trulsson and Johansson (1994). Datapoints coinciding with the pre-load forces used in the current study were extracted directly from the Figs. presented in Parfitt (1960) and Trulsson and Johansson (1994). Y-axes for the current data have been inverted to illustrate the similarity to the previous data.