Quantitative summary of the three components of the synaptic current in AVA evoked by photostimulation of sra-6 expressing neurons. Currents were quantified and subjected to an ANOVA to test for a linear relationship with irradiance. (a) Peak onset transient synaptic current vs. irradiance in animals supplied with all-trans retinal, (ATR(+), blue dots, n = 9) and retinal-free controls, (ATR(−),black dots, n = 4). The magnitude of the onset transient from ATR(+) animals increased significantly with stimulus irradiance (p=0.029) (b) Average sustained synaptic current vs. irradiance. Current was averaged over the interval 0 ≤ t ≤ 2.1 s. Symbols as in a. The magnitude of sustained currents from ATR(+) animals increased significantly with stimulus irradiance (p= 0.044) (c) Average time course of the frequency of unitary synaptic events in response to photostimulation at three different irradiances (horizontal blue bars). The frequency of unitary synaptic events evoked by photostimulaion increased with stimulus irradiance in ATR(+) animals, but this effect did not reach significance (ANOVA, p= 0.246). Upper and lower traces show data from animals supplied or not supplied with all-trans retinal, respectively. ATR(+) n = 9, ATR(−) n=4. Error bars (a–c) are SEM. Statistics (a–c): within-subjects ANOVA test for a linear trend.