Simulation analysis of bandpass filtering properties of a rod photoreceptor network

The bandpass filtering properties of a rod network were studied via computer simulations. Sinusoidal current stimuli were applied to a single rod model to characterize its temporal filtering properties. The simulated frequency response revealed that a single rod behaves as a bandpass filter whose characteristics are affected by the stimulus strength and frequency. We analyzed the contribution of individual ionic currents to bandpass filtering and found that the filtering of small signals is largely regulated by the calcium-dependent currents I(K(Ca)) and I(Cl(Ca)), whereas the filtering of large signals is regulated by the hyperpolarization-activated current, I(h). Furthermore, rod network modeling by electrically interconnecting the single rod models revealed that the acceleration of signals that spread laterally through the rod network is attributed to I(K(Ca)) and not I(h).