Figure 7.
A, Example of lagging the recorded force signal. Same example as in Figure 6A in which the gray line represents the delayed force sensed by the participant and the black line represents a lagged version of this force used to explain the cTBS effect (lag = 40 ms). B, Example of FOP model fitting to original data and lagged data. All the notations are similar to Figure 6B. Black dots represent the lagged force–position trajectory of the example in A. When the FOP model is fitted to the lagged data points (green line), the stiffness slope decreases even further (61.9 vs 85 N/m in this trial). This mimics the increased underestimation of the delayed force field stiffness after PPC cTBS. C, Score of the models predicting participants' answers during the PPC cTBS session. Similar to Figure 6C, the average score of each model is represented by different symbols and colors. For the linear force field, the scores of all models were similar. However, for the delayed force field, we found that the FOP model fitted to the lagged force and hand position data is statistically significantly better than all the other models. This suggests that the cTBS effect can be modeled as a desynchronization between the force and position information. Horizontal lines indicate statistically significant difference (p < 0.05).