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Fig. 7 Substance P modulates presynaptic calcium activity in bipolar cells (A) Expression of the synaptic calcium reporter SyGCaMP6f in synaptic terminals of all bipolar cells throughout the inner plexiform layer. (B) Examples of SyGCaMP6f signals before and after intravitreal injection of the NK1R antagonist L-733,060 in the morning using stimuli of 20% and 60% contrast (1 Hz, full-field modulation). (C) Contrast-response function measured in OFF synapses before (pink) and after blocking NK1Rs (blue) (AM = 83 synapses; AM + L-733,060 = 30 synapses). Each point shows the mean ± SEM, but error bars are not always discernible. (D) Contrast-response function measured in ON synapses before (n = 70) and after (n = 36) blocking NK1Rs (blue). (E) Distribution of peak response amplitudes in the morning averaged across both ON and OFF synapses. Broken lines: 20% contrast. Solid lines, 60% contrast (p < 0.005; KS test). Shaded box indicates stimuli that failed to elicit a significant response.