Figure 3.
Analysis of single-cell responses from 3-month-old and 2.5-year-old mouse rods. A, Families of flash responses from representative adult- (left) and aged- (right) mouse rods. In both cases, 500 nm light test flashes were delivered at time 0, with intensities of 1.7, 4.8, 15.2, 39.4, 125, 444, 1406, and 4630 photons μm−2. Responses to flashes delivering 15.2 photons μm−2 are represented by a thick black line for comparison. B, Population-mean single-photon responses for adult (0.58 ± 0.03 pA, n = 16, solid line) and aged (0.57 ± 0.04 pA, n = 17, dashed line) rods, p > 0.05. C, Normalized averaged intensity-response relations. Points were fitted with saturating exponential functions that yielded half-saturated intensities (I 1/2, indicated by horizontal and vertical dashed lines) of 78 and 120 photons μm−2 for 3-month-old (solid line) and 2.5-year-old (dashed line) mouse rods, respectively.