Fig. 2.

Scanning ion-conductance microscopy (SICM). a, b The operating principle of SICM. A nanopipette, which is provided with a voltage, approaches the surface of the cell, as shown in panel (1) of a. In this process, the current begins to decrease (b). The nanopipette is stopped when the current reaches a certain value [panel (2) in a and point (2) in b]. This step is repeated multiple times; the cell surface is scanned with the probe to create an image on the computer. For details, see the main text. In b, the current was normalized to the bulk steady-state tip ion current, whereas the distance between the probe’s tip and sample’s surface was normalized to the inner radius of the tip. c Images obtained by SICM. Surface morphologies of hippocampal neurons of a rat and cochlear hair cells of a guinea pig were examined by SICM and displayed in left and right panels, respectively. The experiments were performed using protocols published elsewhere [12, 13, 14]