Figure 1.

Pressure application of glutamate solutions from pipettes was controlled by TTL command pulses (A-1, A-2, square pulses). After an initial delay of approximately 9 ms from the command onset (A-2, command and pressure waves), pressure (measured at the BH-2 output) initially increases at an exponential rate (τ = 35–38 ms) over time, due to capacitance in the tubing. Pressure waves for different duration commands (e.g., 50-, 75-, 100-, and 200-ms command pulses, A-3) follow similar time courses. The area (A-4, data, ●; linear fit, dashed line) under the pressure ejection curves increased linearly with trigger pulse durations >50 ms. Excitatory responses of RGC cells (A-1, extracellular recording trace above command and pressure traces) typically occurred after shorter (<200ms) ejections were completed.