Convolution of binary spike trains with a half-Gaussian is used to prepare data for analysis with Granger causality. Illustration of the transform applied to spiking data before running Granger causality analysis. Several example spike trains are shown in gray (A: regular spiking, B: slow bursting, C: fast bursting). In general, raw voltage traces were rasterized (that is, converted to a series of delta functions at the time of each spike) and then convolved with a half-Gaussian function. This converts a point process into a smoother rate function (black traces) that is better suited to Granger causality analysis.