Fig. 4.

Temporal resolution of R1–R6 photoreceptors. (A) Responses of five briefly dark-adapted Coenosia, Calliphora, and Drosophila photoreceptors to a 10-ms saturating light pulse. (B) Normalized impulse responses of five briefly light-adapted photoreceptors to a pseudorandom contrast. (C) SNR of voltage responses to a repeated presentation of bright natural light intensity series. High SNRs (>100) at low frequencies, in which most of the power of natural images resides, implies that signaling is not limited by phototransduction noise. (D) Information transfer of the same responses as in C, calculated as the difference between their entropy and noise entropy (Fig. S3).