Fig. 4

Endogenous serotonin reduces the frequency of spontaneous excitatory synaptic transmission onto ON–OFF RGCs. A Representative traces of the sEPSCs recorded in ON–OFF RGCs under basal conditions (control, black, left) and 10 min after bath application of citalopram (10 µM; gray; right) in wild type (WT; upper traces) and in SERT KO retina (lower traces). B Summarized graphs showing the significant changes in the frequency (**p < 0.01) but not in amplitude of the sEPSC recorded from WT retina (left) after bath application of citalopram. Note that citalopram had no effect on the frequency or amplitude of sEPSC recorded from ON–OFF RGCs in SERT KO retinas (right). Statistical differences were assessed by paired t-test comparison of the means. (WT n = 6 cells/6 animals; SERT KO n = 3 cells/3 animals)