LN model for responses of an OFF parasol ganglion cell. (A) Firing rate in response to multiple trials of the same random stimulus (top). The mean light intensity produced ∼4,000 absorbed photons per cone per second. (B) Excitatory synaptic currents (top) and conductance (bottom) from the same cell in response to the same light stimulus. The cell was voltage clamped and held near the reversal potential for inhibitory input (approximately −60 mV). The conductance was obtained by dividing the current by the −60-mV driving force. The conductance was offset such that the mean conductance before the light stimulus was 0. (C) LN model components for spike response. (D) LN model components for excitatory synaptic conductance.