Fig. 5.

Strychnine depolarized the resting membrane potential and suppressed spontaneous inhibitory noise in OFF cone bipolar cells. A: typical current-clamp recording from an OFF cone bipolar cell where the membrane potential was monitored in the absence (black) and presence (gray) of 1 μM strychnine in darkness and after a flash delivering ∼30 R*/Rod, whose timing is denoted by the downward arrowhead. B: current-clamp recordings of flash families in the absence (black) and presence (gray) of 1 μM strychnine. C: SNR plotted as a function of flash strength for the flash families in the absence (black) and presence (gray) of 1 μM strychnine as shown in B were fit with a saturating exponential function from which response threshold was determined (see materials and methods). D: average SNR plotted as a function of flash strength across 10 OFF cone bipolar cells, with response thresholds of 0.41 ± 0.082 R*/Rod in Ames medium and 0.38 ± 0.096 R*/Rod in Ames medium with strychnine (P = 0.578).