Fig. 2.
Measuring bundle stiffness and bundle dimensions. A: a bundle along the folded edge of the macula is viewed from the side, and a horizontally oriented flexible glass fiber (gold rod) is advanced toward the kinocilium. This bundle was 73 μm from the LPR (zone 3). Image contrast adjusted with ImageJ software. B, left. The glass fiber is brought into contact with the tip of the kinocilium. The fiber's length (L) is much greater than the height of the kinocilium. Right: displacement of the fiber base (δbase) results in bending of the bundle and, thus, displacement of the fiber tip (δtip). We measured displacement of the fiber base with an interferometer and displacement of the fiber/kinocilium tip with photodiodes. C: bundle dimensions. Schematic hair bundle in side view showing the 4 bundle dimensions measured in this study and 2 variables calculated from these measurements (KS ratio and Slope). We measured stiffness of the same bundles to investigate the contributions of bundle structure to bundle stiffness.