Oscillations and noise in paddlefish electroreceptors

The electroreceptors of paddlefish (Polyodon spathula) contain two types of internal oscillators, including a population of stochastic approximate to25 Hz oscillators in the sensory epithelia, and a stochastic 45-65 Hz oscillator in each afferent terminal. The function of the epithelial oscillators is unclear. In other hair cell sensory receptors, oscillations in hair cells have been implicated in frequency tuning, such that the frequency of spontaneous oscillations matches well the best response frequency for external stimuli. However, paddlefish electroreceptors appear to not conform to this concept, since they respond best at approximate to5 Hz, while their approximate to25 Hz epithelial oscillations are 2-3 octaves higher in frequency. Alternate possible functions are discussed, including inducing extended anticorrelations of spike timing, or encoding the water temperature, or acting as internal harmonic noise.