Figure 6. The roles of stochasticity in photoreceptor encoding.

A, 30,000 microvilli in a photo‐sensitive rhabdomere sample incoming photons. B, stochastic photon arrivals to a microvillus population. C, variable QB waveforms and timings in a microvillus. D and E, stochastically operating microvilli resist saturation. Responses to a dim light pulse are not saturated even if a photoreceptor had only very few microvilli, e.g. 3,000 microvilli (D), or 300 microvilli (E). Even when the microvillus number is reduced by 100 times to 300, it is hard to knock out all microvilli at once, because there are always some returning to the pool of available ones at any one moment (responses at black arrow is not flat zero). F and G, stochastic latencies and refractory periods help to prevent saturation and reduce oscillations in photoreceptor output, in comparison to that resulting from a fixed refractory period (black arrows).