The use of a CMOS camera to resolve nanometer displacements of hair cell stereocillia in the bullfrog sacculus

Abstract

A Complementary Metal Oxide Semiconductor (CMOS) camera (1024×1024 pixels) is used to record spontaneous oscillations of hair cell stereocillia in an in-vitro preparation of the bullfrog sacculus with the otolithic membrane removed. The CMOS camera is attached to an Olympus BX51WI Microscope inside of a sound-isolation chamber, with white light transmission illumination using an X-Cite 120 metal halogenide lamp. The combination of the parallel readout of the CMOS chip and the high intensity of illumination allows full frame images of the oscillations to be taken at 1000 frames per second. A weighted, time averaged differential algorithm is used to aid in the visualization of the hair cell movement. To detect the displacement from its center of the stereocillia tip with nanometer position resolution and millisecond time resolution, an average background intensity value was subtracted from each image to remove lamp intensity fluctuations and then a center of intensity algorithm was applied. This combination of our imaging system and data analysis allows for the oscillations of more than one hair cell to be recorded during the same time period, and their frequency components extracted.