Figure 5.
Push-pull signaling in individual hair cells. A, The glutamate release from two hair cells in the same neuromast was measured using the iGluSnFR probe. Although both hair cells were polarized in the negative direction, the one depicted in black was completely rectifying but the hair cell in red could also clearly signal deflections in the positive direction as a decrease in glutamate release. The relationship between cupula deflection and applied pressure in this neuromast was 0.7 deg/mmHg. B, Stimulus–response relations of the hair cells in A. Rmax(1) = 0.81 ± 0.04, Rmin(1) = −0.02 ± 0.07, X1/2(1) = −2.68 ± 0.18°, and Xs(1) = 0.67 ± 0.16, Rmax(2) = 0.47 ± 0.03, Rmin(2) = −0.21 ± 0.05, X1/2(2) = 0.32 ± 0.36°, and Xs(2) = 0.83 ± 0.22. (Axis is reversed to represent the sensitivity to negative deflections.) The relative set-points of the black and red relations were 1 and 0.4, respectively. C, Distribution of the relative set-points from 67 hair cells. Although the majority were strongly rectifying with relative set-points close to 1, there was a large degree of variability. D, The average relative set-points of hair cells within the 13 neuromasts in increasing order.