Figure 7.
Dark rearing reduces cone transmission at eye opening. Cone-dominated ERGs from normal-reared and dark-reared P14 retinas. (A and B) Dark-rearing reduces the cone-driven b-wave at the brightest light intensities. Stimulus families provided short (1–8 ms) photopic flashes of 520 nm light (delivering 495–239,594 photons µm−2). Responses were isolated using the protocol in Fig. 1. (B) Population averaged b-wave amplitudes plotted as a function of flash intensities from normal-reared (nr, closed circles; n = 12 retinas) and dark-reared (dr, open circles; n = 13 retinas) mice. (C) Dark-rearing does not significantly alter the b-wave:a-wave ratio. Response ratios represent averages from normal-reared (nr, closed circles; n = 10 retinas) and dark-reared (dr, open circles; n = 10 retinas) animals plotted as a function of light intensity. (D) Dark-rearing does not alter cone-driven a-wave properties. Blockers were perfused and the same stimulus families from A elicited a-waves (red traces). Insets: Rising phase of the a-wave (black bracket) on an expanded time scale, normalized to Rmax, and fit (superimposed gray traces) with Eq. 4 to obtain the amplification constant (A; s−2). Dashed horizontal = response saturation (Rmax). (E) Population averaged a-wave amplitudes plotted as a function of flash intensity from normal-reared (nr, closed circles; n = 12 retinas) and dark-reared (dr, open circles; n = 10 retinas) mice. Intensity–response relationships were best-fit with Eq. 2 and fit lines appear as follows: normal reared (solid green) and dark reared (dashed green). Vertical lines = half-saturating intensities (I1/2). (F) Dark rearing does not alter the synaptic transfer function. Representative synaptic transfer functions from a single normal-reared (closed circles) and dark-reared (open circles) retina fit with Eq. 6 and appear as follows: nr (solid green), dr (dashed green). Vertical lines = half-saturating a-wave values (solid lines: knr = 26.4 µV; dashed lines: kdr = 18.8 µV). Error bars represent mean ± SEM. Single, double, and triple asterisks indicate P values of <0.05, <0.01, and <0.001, respectively.

Dark rearing reduces cone transmission at eye opening. Cone-dominated ERGs from normal-reared and dark-reared P14 retinas. (A and B) Dark-rearing reduces the cone-driven b-wave at the brightest light intensities. Stimulus families provided short (1–8 ms) photopic flashes of 520 nm light (delivering 495–239,594 photons µm−2). Responses were isolated using the protocol in Fig. 1. (B) Population averaged b-wave amplitudes plotted as a function of flash intensities from normal-reared (nr, closed circles; n = 12 retinas) and dark-reared (dr, open circles; n = 13 retinas) mice. (C) Dark-rearing does not significantly alter the b-wave:a-wave ratio. Response ratios represent averages from normal-reared (nr, closed circles; n = 10 retinas) and dark-reared (dr, open circles; n = 10 retinas) animals plotted as a function of light intensity. (D) Dark-rearing does not alter cone-driven a-wave properties. Blockers were perfused and the same stimulus families from A elicited a-waves (red traces). Insets: Rising phase of the a-wave (black bracket) on an expanded time scale, normalized to Rmax, and fit (superimposed gray traces) with Eq. 4 to obtain the amplification constant (A; s−2). Dashed horizontal = response saturation (Rmax). (E) Population averaged a-wave amplitudes plotted as a function of flash intensity from normal-reared (nr, closed circles; n = 12 retinas) and dark-reared (dr, open circles; n = 10 retinas) mice. Intensity–response relationships were best-fit with Eq. 2 and fit lines appear as follows: normal reared (solid green) and dark reared (dashed green). Vertical lines = half-saturating intensities (I1/2). (F) Dark rearing does not alter the synaptic transfer function. Representative synaptic transfer functions from a single normal-reared (closed circles) and dark-reared (open circles) retina fit with Eq. 6 and appear as follows: nr (solid green), dr (dashed green). Vertical lines = half-saturating a-wave values (solid lines: knr = 26.4 µV; dashed lines: kdr = 18.8 µV). Error bars represent mean ± SEM. Single, double, and triple asterisks indicate P values of <0.05, <0.01, and <0.001, respectively.

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