Figure 2.

A–C, Controls based on simulated data using the firing rate profiles of the neurons presented in Figure 1. They show in solid black the joint-surprise function already shown in Figure 1D. Red curves illustrate statistics (solid indicate mean; dashed indicates 95% confidence limit) of joint-surprise curves resulting from 1000 simulations of independent, parallel spike trains generated as rate-modulated gamma processes based on the rate profiles estimated from the single trials. A, Poisson processes. B, C, Gamma processes with identical (B, κ = 4) and different (C, κ = 3 and 5) shape factors, assumed to be constant throughout the trial. Their choice in C is based on the estimated coefficient of variation (CV₂) for the same pair of neurons (D) and is in the typical range of the whole population of neurons analyzed (E). E, Distribution of the CV₂ values estimated as the average CV₂ during the delay period from PS to GO, for all neurons.