The parameters of GLMs are dependent on the input statistics. (A–C) The effect of the mean current of the injected stimulus on the fitted GLM filters. (A) The relationship between the mean injected current and the resulting firing rate. (B) Stimulus filters of a GP cell for rates of 4–19 Hz varied by increasing the input DC. (C) The corresponding post spike filters. (D–F) The effect of changing the variance of the stimulus while keeping the mean DC constant (subfigures correspond to A–C). (G) The fitted GLM filters of short (5 second) (top) and long (30 second) stimulation periods of the same neuron over different firing rates. (H) The fitted stimulus filters and post spike filters using a GLM that includes an additional firing rate filter over the previous 500 ms of the same neuron over different firing rates.