Fig. 3

Input and output correlations under the five stimulation regimes during the first stimulation session of protocol 1. a Instantaneous firing rate (IFR, gray trace) and instantaneous stimulation rate (ISR, black trace) of a representative experiment under the five stimulation regimes during phase STIM1 of protocol 1. 500 s of activity are reported. Traces are normalized with mean = 0 and std = 1 for ease of comparison. Y-axis is in arbitrary units. Scale bar 100 s. b Box plots of Pearson’s coefficients (PCs) between ISR and IFR for all tested β values as a function of the filter length T (nine experiments, STIM1). c Box plots of PCs computed for each β value, regardless of the filter length used (i.e. each box plot represents 27 values − 9 experiments × 3 filtering window lengths, T = (4, 8, 16) s). Asterisks denote populations whose median values are statistically different (*p < 0.05, Kruskal–Wallis test, post hoc Tukey’s method). d ‘Preferred’ β values for Protocol 1. The bar graph reports the number of stimulation series (nine cultures, two sessions per culture) resulting in the top PC score for each β value tested. Data used to compute the statistical distributions reported in (b), (c) and (d) are included in Additional file 2