Adaptation of single photon responses in photoreceptors of the housefly, Musca domestica: a novel spectral analysis.
The absorption of a photon by a photoreceptor triggers a small voltage fluctuation termed the 'bump'. Here, in the housefly, I introduce the bispectrum of photoreceptor noise to characterise the bump under dim light. The bispectrum provides explicit phase information and is not contaminated by Gaussian background noise. Over the photon rates examined (<10(4) s(-1)), I show that bumps are minimum-phase, noise spectra are little affected by natural variations in bump shape and bumps adapt such that amplitude is approximately proportional to duration squared. In the dark exists a 'dark event', which I suggest represents spontaneous activation of G-protein.
Burton
Brian G
BG
Department of Zoology, University of Cambridge, UK. bgburton@bu.edu
D000221:Adaptation, Ocular / Q000502:physiology*; D000818:Animals; D006793:Houseflies / Q000502:physiology*; D008297:Male; D008839:Microelectrodes; D010775:Photic Stimulation / Q000379:methods; D017785:Photons; D017956:Photoreceptor Cells, Invertebrate / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted; D014785:Vision, Ocular / Q000502:physiology*