Synaptic transmission does not contribute substantial nonlinearities to OFF bipolar cell responses. (A) Cone membrane currents evoked by sinusoidal modulation of the cone membrane potential using 3 Hz waveforms of 4 (−35 to −39 mV, top) and 20 mV (−30 to −50 mV, bottom). Current segments (right) and FFTs (left) are illustrated for both stimulus protocols. Note the very small harmonic evident at 6, 9, and 12 Hz in the responses to 20 mV sinusoids. (B) Postsynaptic currents evoked in OFF bipolar cells by sinusoidal modulation of cones by 3 Hz waveforms of 4 (top) and 20 mV (bottom). Synaptic current waveforms (right) and FFTs (left) are illustrated for both stimulus protocols. For both cone and OFF bipolar cells, responses with 20 mV waveforms were averaged from single trials across 12 cells. For the 4-mV waveform, responses were averaged from 16 trials across 12 cells.