Title : Temporal coding by populations of auditory receptor neurons 1 Running head : Temporal coding by populations of receptor neurons

15 Auditory receptor neurons of crickets are most sensitive to either low or high 16 sound frequencies. Earlier work showed that the temporal coding properties of first-order 17 auditory interneurons are matched to the temporal characteristics of natural low18 frequency and high-frequency stimuli (cricket songs and bat echolocation calls, 19 respectively). We study the temporal coding properties of receptor neurons, and use 20 modelling to investigate how activity within populations of low-frequency and high21 frequency receptors might contribute to the coding properties of interneurons. We 22 confirm earlier findings that individual low-frequency-tuned receptors code stimulus 23 temporal pattern poorly, but show that coding performance of a receptor population 24 increases markedly with population size, due in part to low redundancy among the spike 25 trains of different receptors. By contrast, individual high-frequency-tuned receptors code 26 stimulus temporal pattern fairly well and, because their spike trains are redundant, there 27 is only a slight increase in coding performance with population size. The coding 28 properties of low-frequency and high-frequency receptor populations resemble those of 29 interneurons in response to lowand high-frequency stimuli, suggesting that coding at the 30 interneuron level is partly determined by the nature and organization of afferent input. 31 Consistent with this, the sound-frequency-specific coding properties of an interneuron, 32 previously demonstrated by analyzing its spike train, are also apparent in the sub33 threshold fluctuations in membrane potential that are generated by synaptic input from 34 receptor neurons. 35