POSTER PRESENTATION Open Access Predictable implications of random photon absorption for photoreceptors ’ gain control

Light intensities change enormously in terrestrial envir-onments, from murky starlit night to scorching daylight [1]. Photoreceptors of land animals have evolved with specialized photon absorption structures and adaptive mechanisms to cope with this large input range. They can effectively encode the vastly varying light intensities to macroscopic voltage responses, capturing the temporal structure of natural contrast changes within their limited output range. However, if photoreceptors were purely photon counters, counting every single photon that hits them, their outputs would readily saturate at bright day-light. To lessen this problem, it has been suggested that sublinear summation in quantum bump production (quantum-gain nonlinearity) may reduce the bump/ photon gain at the instances when multiple photons hi