Figure 1.

Recording from hair cells and calyceal afferent terminals in the rat saccular epithelium. A, Confocal image of the saccular epithelium excised from a P2 rat (modified from Fig. 2C in Eatock and Songer, 2011). The striolar zone is overlaid with red; most recordings were made from the region between the two blue arrows. The tissue was stained with phalloidin, which labels the actin-based hair bundles, with antibodies to β3-tubulin, which labels all nerve fibers, and with calretinin, which labels type II hair cells and calyx-only striolar nerve fibers. B, Schematic, illustrating a “triple” calyx around three type I hair cells, shows two recording electrodes, one on a hair cell and one on the calyx. Just one recording electrode was used at a time. A stimulus probe (open circle) was positioned against the staircase edge of the hair bundle to deflect it along its most sensitive axis (double arrow above bundle) while recordings were made in whole-cell patch-clamp mode from either the type I hair cell or its postsynaptic calyx. C, Stimulation and recording from a striolar type I hair cell, as viewed from above with differential-interference-contrast or fluorescence optics. Top, The hair bundle was deflected along its sensitive axis with a rigid glass probe. Bottom, The soma below the hair bundle, filled with fluorescent rhodamine diffused in from the recording pipette (electrode). Scale bar in D applies to C. D, Recording from a triple calyx, as viewed from above. Top, The hair bundles of the three type I hair cells within the calyx are outlined (red). Bottom, The recording electrode has filled the triple calyx terminal with rhodamine.