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. 2017 Sep 5;6:e26117. doi: 10.7554/eLife.26117

Figure 1. Photoreceptors respond best to high-contrast bursts.

(A) Schematic of intracellular recordings to repeated bursty light intensity time series (20 Hz bandwidth). Responses changed little (minimal adaptation) during bursts. (B) Testing a R1-R6 photoreceptor’s diurnal encoding gamut. Means (thick traces) and 20 individual responses (thin; near-perfectly overlapped) to 20 different stimuli; each with a specific bandwidth (columns: from 20 Hz, red, to 500 Hz, blue) and mean contrast (rows). Reducing the background (BG) of Gaussian white-noise stimuli (GWN; 2-unit peak-to-peak modulation) from bright (1.5-unit, bottom) to dark (0-unit, top) halved their modulation, generating bursts of increasing contrast: the lower the BG, the higher the contrast. Left-top: responses from (A). Yellow box: maximum information responses. Arrows: dark intervals. Because of half-Gaussian waveforms, light bursts carried fewer photons (see Figure 2—figure supplement 3). Yet their larger responses comply with the stochastic adaptive visual information sampling theory (Song et al., 2012; Song and Juusola, 2014; Juusola et al., 2015) (Appendixes 1–3), whereby dark intervals rescue refractory microvilli for transducing high-frequency (1–20 ms) saccadic photon surges (of high contrast) into quantum bumps efficiently. Thus, larger responses would incorporate more bumps. Recordings are from the same photoreceptor. Vertical dotted rectangle (orange square) and horizontal rectangle (black circle): responses for contrast and bandwidth analyses in Figure 2A. Similar R1-R6 population data is in Figure 1—figure supplement 1.

Figure 1—source data 1. Intracellular voltage responses of the same R1-R6 photoreceptor to very bright 20 Hz, 50 Hz, 100 Hz, 200 Hz and 500 Hz bursty light stimuli at BG0 (darkness).
elife-26117-fig1-data1.xlsx (2.2MB, xlsx)
DOI: 10.7554/eLife.26117.005
Figure 1—source data 2. Intracellular voltage responses of the same R1-R6 photoreceptor to very bright 20 Hz, 50 Hz, 100 Hz, 200 Hz and 500 Hz bursty light stimuli at BG0.5.
elife-26117-fig1-data2.xlsx (2.2MB, xlsx)
DOI: 10.7554/eLife.26117.006
Figure 1—source data 3. Intracellular voltage responses of the same R1-R6 photoreceptor to very bright 20 Hz, 50 Hz, 100 Hz, 200 Hz and 500 Hz bursty light stimuli at BG1.
elife-26117-fig1-data3.xlsx (2.4MB, xlsx)
DOI: 10.7554/eLife.26117.007
Figure 1—source data 4. Intracellular voltage responses of the same R1-R6 photoreceptor to very bright 20 Hz, 50 Hz, 100 Hz, 200 Hz and 500 Hz bursty light stimuli at BG1.5.
elife-26117-fig1-data4.xlsx (2.2MB, xlsx)
DOI: 10.7554/eLife.26117.008

Figure 1.

Figure 1—figure supplement 1. R1-R6 output varies more cell-to-cell than trial-to-trial (cf.Figure 1) but show consistent stimulus-dependent dynamics over the whole encoding range.

Figure 1—figure supplement 1.

(A) The mean voltage response and SD of 15 R1-R6 cells to the same repeated 20 Hz bandwidth bursts. Photoreceptor output adapts within ~2 s to the stimulation. (B) Population means (thick) and 4–16 mean voltage responses of individual photoreceptors (thin traces) to 20 different stimuli; each with specific bandwidth (columns: from 20 Hz, red to 500 Hz, blue) and mean contrast (rows). Stimulation changes from Gaussian white-noise (GWN; bottom) to bursts (top) with the light background: from BG0 (dark) to BG1.5 (very bright). Left top: the traces from (A). The yellow box indicates the responses with the highest entropy and information content. Vertical dotted rectangle (orange square) and horizontal rectangle (black circle): responses for contrast and bandwidth analyses in Figure 2—figure supplement 1A. All recordings were done at 25°C. Compare this data to Figure 1.