Fig. 1.
Spontaneous activity increases with photoreceptor degeneration in rd1 and rd10 ganglion cells. (A) Representative raster plots display extracellular recordings of spontaneous action potentials in wild type (wt), rd1, and rd10 at postnatal ages of 8 weeks. Each panel displays the RGC activity recorded over 10 sec period in a sample of 16 ganglion cells (1 per row) from a single retina. (B) Mean±SEM firing rate of all cells recorded across different postnatal ages. Spontaneous activity significantly increases with aging from postnatal 4 weeks to 8 weeks both in rd1 and rd10 ganglion cells (p<0.05). At PNW8, the mean spike frequency of wt is significantly lower than either rd1 or rd10 (***p<0.001). In rd10, the mean firing rate at PNW8 and PNW30 are highest, and no statistical difference among the other age groups (ANOVA, p=0.05, posthoc Tukey criteria). Statistically significant differences among different age groups are indicated above the mean value (*p<0.05). (C) Median spontaneous firing rates (middle line in each bar) and 1st and 3rd quartiles (ends of bars) are indicated for each of 6 age groups. The median spike rate at PNW8 is the highest, and at PNW30, second highest, and no difference among PNW4, 10, 15, and 20 (Kruskal-Wallis test, p=0.05, Tukey's criteria). Statistically significant differences among different age groups are indicated above the median value (*p<0.05). Data are from the same recordings in B. The number of cells in each sample is indicated above the bar, with the number of retinas in parentheses. Each retina was from a different animal.