Fig. 5
Relation between mean stimulation rate and I/O correlation. In the two scatter plots, each dot represents a 10-min stimulation phase. On the X axis, the average stimulation rate is presented, while the Y axis shows the PC obtained following a pre-filtering with an 8 s long window. At X = 0.5, the relevant PCs from the experiments performed with protocol 1 during STIM1 are represented, while the remaining points are relative to the PCs obtained during the first stimulation sessions of protocol 2. The gray fitting line is obtained as a linear interpolation using the natural logarithm of the MSR values as Xs and the PCs as Ys. The fitted slope is −0.031, with 95% confidence bounds at −0.083 and 0.02 (lower and upper, respectively) and a R2 value of 0.0054 for the graph in the left panel, relative to β = 1. The fit for the data represented in the graph reported in the right panel (β = ∞) results in a slope of −0.13 (95% confidence bounds are −0.16, −0.097) and a R2 of 0.66. Data reported in panels (a) and (b) are included in Additional file 2