RESPONSE VARIABILITY AND TIMING PRECISION OF NEURONAL SPIKE TRAINS IN-VIVO

We report that neuronal spike trains can exhibit high, stimulus-depend ent temporal precision even while the trial-to-trial response variabil ity, measured in several traditional ways, remains substantially indep endent of the stimulus. We show that retinal ganglion cells and neuron s in the lateral geniculate nucleus (LGN) of cats in vivo display both these aspects of firing behavior, which have previously been reported to be contradictory. We develop a simple model that treats neurons as ''leaky'' integrate-and-fire devices and show that it, too, can exhib it both behaviors. We consider the implications of our findings for th e problem of neural coding.