Fig. 4.
Light adaptation abolishes GABACR input to OFF bipolar cells. A and B: example GABACR-mediated L-IPSCs recorded from an OFF type 4 bipolar cell in the dark- and light-adapted conditions (CW = 67, CM = 0.971), black and gray traces, respectively (1-s flash of a 25-μm bar of light, −200, 0, and 200 μm away from the recorded cell). Light adaptation abolished all GABACR-mediated input. Light stimulus is indicated by gray bars under L-IPSCs; OFF type 4 bipolar cells respond at the onset of light. C and D: spatial inhibition curves of GABACR-mediated Q, normalized to the center bar stimulus, and of peak amplitude in the dark- and light-adapted conditions. There was no GABACR-mediated inhibition after light adaptation (n = 6). E: dark-adapted spatial distribution curves of normalized GABACR-mediated (n = 6) and total GABAergic (n = 4) spatial input. GABACR-mediated spatial input was significantly narrower than total GABAergic input. **P < 0.01.