Figure 8.

Augmenting the response of the ON bipolar cell increases rectification, increases gain, and reduces the middle frequency of excitatory currents in OFF ganglion cells. A, Excitatory currents from an OFF ganglion cell in control conditions and with TPMPA. Some current deflections returned to the baseline when TPMPA was applied, consistent with an increase in rectification (arrows). B, Static nonlinearities from the same cell. TPMPA increased the slope of the linear portion. Inset, TPMPA made the static nonlinearity more curved, consistent with an increase in gain and in rectification. C, Most cells lie above the diagonal, indicating that TPMPA increased rectification (13 G5, 2 unclassified). D, TPMPA increased gain in all cells. E, TPMPA decreased power at all frequencies. Inset, Spectra normalized to peak power show that TMPA decreased power at high frequencies more than at low frequencies. F, TPMPA reduced the middle frequency of the power spectrum for almost all cells. Note: The four red cells in C and F were subjected to additional control experiments (Fig. 9).