A, Four rods recorded in flat-mounted salamander retina with the multiple electrode recording system. B, Original locations of the four rods before recording. C, Voltage responses of Rod1,0; Rod0,1; Rod0,2; and Rod0,1 to a −1 nA current step (1 s) injected into Rod0,0. D, Same experiments as in C except that Rod0,1 was voltage clamped at −40 mV.