Temporally Precise Spiking in the Presence of Synaptic Noise

Spike timing precision and reliability were studied in granule cells of the dentate gyrus using conductance inputs based on natural synaptic properties and injected via dynamic current clamp. Precision and reliability were greater for conductance steps than for current steps, and were greatly enhanced for synaptic conductance waveforms. Precision and reliability were only slightly degraded by realistic trial-to-trial synaptic fluctuations. We therefore examined, in the presence of realistic noise, the effects of 1) varying the ratio of inhibition to excitation, 2) varying the number of inputs and 3) correlated inputs, on both temporal and rate-based features of granule cell coding.