The name is absent

15

ing to the recorded response, some recordings were made from single dissociated cells, and
the results compared against the data from the whole mount retina. These responses cells
fell within the range for recordings from the whole mount retina (figure 3.1 A2). Although
rod-rod coupling appears to play an important role in propagating small electrical signals be-
tween adjacent rods, it does not affect our characterization of the kinetics of the Ih current in
a single cell. Our experiments involve much larger currents, making the contribution from
neighboring cells negligible compared to the current induced in the recorded cell. Given a
rod impedance of, 550 MΩ and a coupling resistance of 2 GΩ [115], this would result in the
adjacent cell being hyperpolarized at most to -57 mV in our experiments, where a propor-
tionally small Ih current is generated (figure 3.1 A3, B3). Only part of this activated current
in adjacent cells would flow back into the voltage clamped cell.

Light Responses

Light responses were recorded using current clamp mode. Rs compensation in the EPC-
10 acted as a bridge to ensure that the voltages were properly scaled. Light stimuli were
generated by converting the voltage from the D/А converter on the amplifier into a current
source via an bp-amp, which was used to drive either a 627 nm or 530 nm Luxeon K2 LED
(Phillips). The light output from the LEDs was found to be proportional to the drive current.

Impulse Responses

We estimated the impulse response of photoreceptors using the 627 or 530 nm LED light
source modulated with 30 Hz gaussian white noise. The noise was generated in MATLAB

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