Synaptic Transmission from Horizontal Cells to Cones Is Impaired by Loss of Connexin Hemichannels
Figure 9
Optokinetic response of mutant zebrafish is reduced.
(A) Eye movements of a wild-type zebrafish larva (black, right eye; red, left eye). Timing of the stimulus is indicated in the bottom trace. (B) Optokinetic gain as function of contrast for 13 wild-type (black) and 13 mutant (red) zebrafish. Over the whole contrast range the wild-type performed significantly better than the mutant. (C) In the mutant, reduction in optokinetic gain is stronger for high temporal frequencies (1.0 cycle per second) than for low temporal frequencies (0.25 cycle per second) (p = 0.017). (D) In wild-type the temporal frequency transfer function of cones to bipolar cells is a band-pass filter. The low frequency cutoff is due to negative feedback from horizontal cells. When removing this pathway and inducing an overall gain reduction, the transfer function changes into a low-pass filter. At low frequencies this transformation leads to a smaller loss in gain than for high temporal frequencies.