Fig. 5. Modeling the rod network. *A*, Diagram of the rod network (adapted from Attwell, 1986). The rods (filled circles) are organized into a square array with the cones (open circles) between the rods. Lines between cells indicate electrical coupling. In this model the rod array was cut horizontally. The black circle is the primary rod to which the voltage signal is applied. The red, orange, green, and blue circles are the second, third, fourth, and fifth rods, respectively, downstream from the primary rod. The stimulus applied to the primary rod was 10 mV in amplitude centered around −40 mV. The stimulus frequency varied from 0.1 to 16 Hz. The resting potential of the other rods in the network was −40 mV.*B*–*E*, RC circuit model of the rod membrane. *B*, Diagram of the model RC circuit. The rod membrane is modeled as capacitor (*C*_{m}) in parallel with a resistor (*R*_{m}). Each rod in the array is connected to neighboring rods through a coupling resistance (*R*_{c}). The values of the circuit elements used in this model are*R*_{c} = 300 MΩ,*R*_{m} = 0.5 GΩ, and*C*_{m} = 26 pF. *C*, Modeled voltage signal in each cell type resulting from a 2 Hz sinewave applied to the primary rod. *D*, Plot of amplitude of the voltage change in each cell versus frequency. *E*, Plot of the phase of the voltage change in each cell versus frequency.*F*–*I*, RL circuit model of the rod membrane (Owen and Torre, 1983; Torre and Owen, 1983).*F*, In this model the rod membrane is modeled as an inductor (*L*) in series with a resistor (*R*_{2}), both of which are in parallel with a second resistor (*R*_{1}). As in the RC model, each rod is connected to neighboring rods through a resistor (*R*_{c}). The values of the elements in this model are *R*_{C} = 360 MΩ, *L* = 0.5 GH,*R*_{1} = 710 MΩ, and*R*_{2} = 3.3 GΩ (Owen and Torre, 1983).*G*, Modeled voltage signal in each cell type resulting from a 2 Hz sinewave applied to the primary rod. *H*, Plot of amplitude of the voltage change in each cell versus frequency.*I*, Plot of the phase of the voltage change in each cell versus frequency. Colors are consistent throughout the figure. Note that although the rods straight above the primary rod have three downstream cells, those horizontal or diagonal from the primary rod have only two downstream cells. Although the data shown in this figure are only from the rods that have two downstream cells, our final model included the contribution made by the rods with three downstream cells.