Fig. 8

A Examples of synaptic responses over 11 different contrasts spanning ±10% around the contrast eliciting the half-maximal response (C_1/2) in the morning (top, light red), afternoon (middle, dark red) and after injection of D1 antagonist SCH 23390 in the afternoon (bottom, black; note the lower frequency and amplitude of release events). In each case the top trace shows the iGluSnFR signal and the lower trace the estimated Q_e. Each contrast step lasted 2 s (5 Hz) and each trace is from a different OFF synapse. B Mutual information I (S:Q) in four conditions: morning (Morn AM; OFF = 15 synapses, ON = 10 synapses), morning after injection of ADTN (Morn + D1; OFF = 14 synapses, ON = 6 synapses), afternoon after injection of SCH 23390 (After−D1; OFF = 12 synapses, ON = 6 synapses) and afternoon (After PM; OFF = 33 synapses, ON = 13 synapses). Differences between morning and afternoon were significant at p < 0.0001 (One-way ANOVA), as were the effects of drug manipulations. Bar graphs show the mean ± s.e.m. Individual values are represented by green and red open dots for ON and OFF synapses, respectively. C Specific information (I) for events of different quantal content in OFF synapses (morning, n = 15; afternoon, n = 33). The curve describing the relation are least-squares fit of a power function of the form I = y0 + AQ_e^x. In the morning, y₀ = 0.38, A = 0.0017, x = 3.4. In the afternoon, y₀ = 0.12, A = 0.10, x = 1.2. Each point shows the mean ± s.e.m. D As (C), but for ON synapses (morning, n = 10; afternoon, n = 13). In the morning, y₀ = 0.24, A = 0.0003, x = 4.4. In the afternoon, y₀ = 0.16, A = 0.11, x = 1.0. Each point shows the mean ± s.e.m. Source data are provided as a Source Data file.