Fig. 6

A Example recordings from two OFF synapses stimulated at 60% contrast in three conditions: afternoon (top, red trace), morning (middle, light red trace) and after intravitreal injection of ADTN in the morning (bottom, blue trace). Morning and morning + ADTN synaptic responses are from the same synapse. The modulation in intensity (5 Hz, sine wave) is shown below. Arrowheads highlight events occurring at different phases of the stimulus, with less variation with events composed for 4 or more quanta in the afternoon and after administration of ADTN in the morning. In each case the top trace shows the iGluSnFR signal and the lower trace the estimated Q_e. B Temporal jitter of events composed of different numbers of quanta in OFF synapses in the afternoon (red dots; n = 24 synapses); Morning (open red dots; n = 19 synapses) and Morning + ADTN (blue dots, n = 16). Note that during the morning events composed by multiple quanta were less phase-locked to the stimuli in comparison to the afternoon. Activation of D1 receptors had a significant effect on release of multiquantal events. Events composed by 5 or more quanta jittered by ~5 ms, similar to values observed in the afternoon (black dashed line). The solid lines describing these relations in the three conditions are better described by a single exponential decay function of the form y₀ + A_exp((−(x−x₀)/τ))) with y₀ = 4.23 ± 1.2 and A = 27 ± 7 in the afternoon; y₀ = 9.77 ± 1.4 and A = 28.64 ± 5.6 in the morning and y₀ = 5.45 ± 1.3, A = 30 ± 6.1 after activation of D1 receptor in the morning. Each point shows the mean ± s.e.m. C Temporal jitter of events composed by different numbers of quanta measured in ON synapses in the afternoon (green dots; n = 14 synapses) during the morning (open green dots; n = 10 synapses) and during Morning + ADTN, (blue dots; n = 6 synapses). Activation of D1 receptor did not have a significant effect in the temporal precision in the ON channel. The relationships observed in the different conditions were better described by a straight line. Morning a = 34.7 ± 1.5 and a slope = −3.6 ± 0.5; Afternoon: a = 25.1 ± 1.2 and a slope = −2.8 ± 0.2; Morning + ADTN: a = 34.9 ± 1.5 and a slope = −4.2 ± 0.3. Note that events composed of 8 or more quanta jittered by just ~4 ms (black dashed line). Each point shows the mean ± s.e.m. Source data are provided as a Source Data file.