Figure 5. Response waveforms and time course of I_RC and I_HC.

A, rod–large single cone pair; B, rod–HC_B pair. Panel a, Lucifer Yellow fluorescent images of a rod–cone pair in the flat-mounted retina (A) and a rod–HC pair in the living retinal slice (B). Calibration bars, 20 μm. Panel b, current responses of the cone (I_Cone, held near its dark potential at −30 mV; A) and current responses of the HC (I_HC, held near its dark potential at −20 mV; B) to the same set of voltage clamp steps in rods (V_Rod, −130 to +10 mV). Blue arrows, I_HC; green arrows, I_j; red arrows, I_RC. Panel c, current responses of a large single cone cone (I_Cone, held near its dark potential at −30 mV; A), and current responses of a HC_B (I_HC, held near its dark potential at −20 mV; B) to the same set of negative voltage clamp steps (−50 to −130 mV) of various durations (10 –300 ms) in rods. Red arrows, I_RC; blue arrows, I_HC. I_RC is accompanied by a sustained I_j (green arrows) whereas I_HC is not. The red and blue arrows mark the same time points of each I_RC and I_HC response pairs, showing that I_RC and I_HC peak approximately at the same times. Panel d, normalized, average (error bars =±SD, N = 11 for rod–cone pairs and 6 for rod–HC_B pairs) amplitude–duration plots of I_RC (red filled circles) and I_HC (blue open circles).