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. 2009 Jul 1;29(26):8372–8387. doi: 10.1523/JNEUROSCI.1218-09.2009

Figure 3.

Figure 3.

Blue-ON cells have rod-ON responses at low retinal illuminances. A, Blue-ON responses to 1500 ms blue and green primary LED light steps measured across a 4 log unit illuminance range with the integrated irradiance (photons/s/μm2) of the blue primary LED light decreasing from 1.8 × 105 to 1.7 × 104 to 1.4 × 103 to 9.4 × 101 photons/s/μm2 (top to bottom) and the green primary LED light from 6.9 × 105 to 8.1 × 104 to 8.5 × 103 to 5.3 × 102 photons/s/μm2 (top to bottom). The number of photoisomerizations/s/cone for the blue and green primary LEDs at each light level was calculated for S cone:rod (left) and LM cones:rod (right), respectively, and are indicated above each trace. B, Rod-ON responses were at least twice as slow as cone-ON responses to the blue primary LED (left) and to cone OFF responses to the green primary LED (right). The time (in milliseconds) to the first spike after the onset or decrement of the primary LED is indicated for each trace. The number of photoisomerizations/s/cone of S cone:rod (left) and LM cones:rod (right) for the blue and green primary LEDs, respectively, are indicated above each trace. C, The small bistratified cells rod-ON responses (solid circles) do not respond to modulation >10 Hz, whereas S-ON responses at high photopic light levels (open circles) respond to much higher temporal frequencies (see Fig. 5 for responses to S cone-isolating stimuli). Plots show the normalized average ON-rod response (left) and phase (right) to 100% contrast sine waves modulated at different temporal frequencies; error bars indicate SD (n = 10). The response latency calculated from the phase was ∼5 times slower (177 ± 36 ms, mean ± SD; n = 10) than cone latencies (40 ± 3 ms, mean ± SD; n = 20) as calculated for S cone-isolating stimuli at photopic light levels (see Fig. 5D). D, Rod ON responses measured at low retinal illuminances to both the blue and green LED primaries were eliminated with bath application of l-AP4, the mGluR6 receptor agonist. Photoisomerizations indicated as in A and B.