Measuring information transfer in the spike generator of crayfish sustaining fibers

We present a method based on information-theoretic distances for measuring the information transfer efficiency of voltage to impulse encoders. In response to light pulses, we simultaneously recorded the EPSP and spiking output of crayfish sustaining fibers. To measure the distance between analog EPSP responses, we developed a membrane noise model that accurately captures stimulus-induced nonstationarities. By comparing the EPSP and spike responses, we found encoding efficiencies on the order of 10^–4, with interesting dynamics occurring during initial transients. A simple analog to point-process converter predicted the small information transfer efficiencies and dynamic properties we measured.